Lightning Protection
Alan Jones (W4LGH)
on
July 24, 2007
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How do you try to protect yourself and your shack equipment from lightning? We all have that same worry lurking in the back of our heads 24/7! I have read many articles on this subject, with many different ways to approach a safe way. The term ground is somewhat a moot point with dealing with lightning, since lightning contains many RF frequencies, you can ground one but the others come thru.
I have heard many say, I disconnect the coax and throw it out the window. While this maybe one of the safest ways, it can be a real pain to do, and then to reconnect.
Many companies make lightning protection devices, but do they work? Polyphaser, ICE, MFJ to name a few, make devices to bleed off high voltages thru the use of fast acting gas tube discharge, while this is good, they are NOT intended to replace a good ground system in your shack.
Since I was building a new house, I was able to install copper screen wire behind my sheetrock across the ceiling and down the walls. All of this is bonded together creating a faraday shield around my shack, and then bonded to a 10' rod right outside on the other side of the wall. Polyphaser devices are inline and bonded to the same grounding system. A #2 copper wire then comes from the ground rod and makes a bonding strap running along the back of my equipment tables. As a final touch, I use an elaborate antenna switching system with the last position directly connected to the bonding strap. -- So when it is all said and done, all of my equipment is disconnected from the outside world, and all antennas go directly to my ground system.
So far so good with the lightning storms we get here in Florida. Just had a nasty one this past weekend with 2 hours of serious cloud to ground lightning popping all around me, with some to close for comfort.
How do you protect yourself?
73 de W4LGH - Alan
http://www.w4lgh.com
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Lightning Protection
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by K9KJM on July 24, 2007
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A single 10 foot ground rod is really.... Not enough... Nor is a single #2 copper wire enough.
(Most all direct lightning strikes will NOT "Melt" a #2 copper wire, BUT the object is to get all of that energy to ground FAST. Copper strap is really the correct item to run from a single point ground out to your ground system, That consists of a number of interconnected ground rods (Space the rods twice the distance apart as the depth)
For some good information see:http://members.cox.net/pc-usa/station/ground0.htm
(also be sure to go to the links provided above, Especially the Polyphaser site)
And the articles Ron Block wrote for QST a few years ago is also good:
http://www.arrl.org/tis/info/pdf/0208053.pdf
Repeater sites, Police, Fire, etc radio towers, Cellphone tower sites, Broadcast towers, High rise buildings, etc etc all take direct lightning strikes most every storm. So do my own towers. And suffer NO DAMAGE when they are properly set up.
It is not all that easy to do a correct lightning protection system, But does NOT have to cost all that much money. USED copper wire will work as well as brand new, Copper roof flashing from upscale roofers is as good as the stuff sold for lightning grounding, etc etc.
Those who "disconnect" coax when dark clouds come are living in a fools paradise, Not to mention risking personal safety doing so. To leave coax lay about without being properly grounded is like leaving dynamite laying on your floor!
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RE: Lightning Protection
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by KE3WD on July 24, 2007
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POLYPHASER
Because it works.
Hit after direct hit.
If you follow their directions.
.
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Lightning Protection
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by NA4IT on July 24, 2007
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All of my antenna connections are mounted in a metal bulkhead, which is in turn grounded via a #4 wire going out to an 8 foot ground rod (only 4 1/2 feet away). My old fashioned Heathkit coax switch is also bonded to the bulkhead. When storms come, I disconnect the rigs, move their jumpers to the side, and I have a series of banana plug that connect into the centers of the open connectors, and they too are grounded.
I have found that is you keep the static charge from building up on your antenna system to start with, then you effectively stop lightning strikes, as the "leader" emitting from the ground that attracts the lightning strike is not there.
NA4IT
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RE: Lightning Protection
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by KB9CRY on July 24, 2007
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but do they work?
Yes they do. Ask any commercial or police or fire radio station; they never disconnect and they get hit all the time. And yes, they are also using Polyphasers or ICE devices.
Alan, you have one missing element in your grounding system. You NEED to bond your SPG to your electrical service entrance ground. In your described setup you missed one element of a good ground system. Also bond your SPG to your antenna/mast/tower ground system.
The Polyphaser and ICE technical articles are a must read.
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Lightning Protection
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by W4WGA on July 24, 2007
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Being at the highest ground for a couple of miles with few trees I am very wary of lightning. Before installing my station we had had a couple of strikes. One taking out a tree and the other my QFH antenna along with the telephone system and two computers so I did a lot of preparation before setting up my home built 50' tilt/crank up. The soil is good but about 5' down is solid granite so driving rods down 8' is problematic.
The tower has four 5' rods connected in a radial pattern to the base of the tower with 8' runs of 1/2" copper tube and a ring of tubing buried about 8" connects all the the rods together. All rods are cadwelded and all the rebar in the footing is welded together. All coax, rotor and switch controls go to ICE suppressors in the tower wiring box. All cable run in burried 1 1/2" EMT to the station entrance.
The station entrance is an 1/8" copper plate cut to fit the frame of a double hung window with another set of ICE suppressors and 3 Polyphasors for the wire antennas. One 3" wide strip of copper foil and two runs of 1" ground braid connect the station entrance to the primary ground rod. The primary is 4' from the station entrance. Six additional rods in pairs spaced 8' apart radiate out from the primary connected with marine grade #2 stranded. All rods are cadwelded. As the station is at the opposite end of the house from the service entrance a bare #4 wire runs around the house to the entrance ground rod.
Inside the shack all coax goes to switches which ground out the antennas when not in use.
Even with no rain for 2 months my Extech ground tester read under one ohm at both grounds but I still keep my fingers crossed.
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RE: Lightning Protection
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by KB9CRY on July 24, 2007
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Glenn, if I may, I'd like to make a few comments based on your description of your grounding system.
Ground rods should be spaced every 2X their height. So if you can't drive them 8 feet down but only 5 feet down, then you'd do that and space them every 10 feet apart.
Polyphaser recommends 75 feet of ground radials (with rods every 2X their height) per tower leg. Sounds like you may want to beef up that portion of your excellent system.
Actually we shouldn't be as concerned with direct strikes (happens but very infrequent) but with indirect strikes. A lightning strike a mile away can induce enough current to zap electronics.
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Lightning Protection
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by DXSHORTWAVE on July 24, 2007
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We replaced the PolyPhaser units at our commercial HF monitoring and relay stations with Alpha Delta TT3G50 units. The internal capacitors in the PolyPhaser units started to fail when running just 1000 watts carrier. They were only 2-3 years old.
We had an independent lab test and evaluate both types and found the Alpha Delta units to work better and take higher discharges. We don't use any blocked LC designs anymore, in any of our stations worldwide. due to field failures. The Alpha Delta units have been problem free. One of our Army military customers uses Alpha Delta units in their comm control vans in the Middle East and have them on their recommended lists.
Major grounding techniques are also essential as our stations must stay on 24-7 like public service stations (police, fire, etc.). Lightning protection is not a trivial matter and must be dealt with as a very serious matter. Just disconnecting the coax feeders can lead to some very damaging results as lightning induced discharges can jump several feet from the end of an unterminated feedline.
I find it important to state all this because 24-7 stations can't afford to go down due to a failure of any component. Hams should be aware of this too.
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RE: Lightning Protection
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by W4LGH on July 24, 2007
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NA4IT said.."I have found that is you keep the static charge from building up on your antenna system to start with, then you effectively stop lightning strikes, as the "leader" emitting from the ground that attracts the lightning strike is not there."
I too have found this to be true. I writing the article, you always miss something, and I failed to include the 2nd 10' ground rod located back at the antennas. This is where my remote switch box is located and mounted on a 10'mast pole also driven into the ground about 7' an dthe 10' copper ground is just off to the side of that and is bonded to it. All teh polyphasers are on the output side of the switch, and are also bonded to the 10' ground rod, so there are always online. This back ground is also on teh edge of wetlands and measured an wonderful 12ohms!
My house ground measured a tad over 25ohms, and this is why I did not bond the 2 grounds together, as that difference in potential could cause a problem. The power in my shack goes thru several isolation transformers, which removes the house ground in the shack as well. Isolation transformers also help with line spikes, as usually the core of the transformer can not charge that quickly.
Soooo...now theres the whole story, a lot of time and money was spent and so far, so good. Also remember that when the switch is flipped, the antennas are grounded out , AT the antennas, the coax coming back to the shack is also burried.
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by AA4PB on July 24, 2007
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The National Electric Code *requires* the station grounds to be bonded to the electrical service ground. One reason is exactly what you are seeing - a difference in potential between the grounds. If someone were to come into contact with the radio case and the case of something connected to the electrical service ground (i.e anything with a metal case and a 3-wire plug) he might receive a shock.
The other reason is that a lightning strike might come in on the power system. If there is no bonding to provide a low impedance path between the electrical system and your radio ground, it might take some other path to get to your better ground. A likely path would be through your radio equipment which could include the insulation between the windings on one of the isolation transformers. Other paths might include something flammable that could start a fire.
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RE: Lightning Protection
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by AA4PB on July 24, 2007
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The National Electric Code *requires* the station grounds to be bonded to the electrical service ground. One reason is exactly what you are seeing - a difference in potential between the grounds. If someone were to come into contact with the radio case and the case of something connected to the electrical service ground (i.e anything with a metal case and a 3-wire plug) he might receive a shock.
The other reason is that a lightning strike might come in on the power system. If there is no bonding to provide a low impedance path between the electrical system and your radio ground, it might take some other path to get to your better ground. A likely path would be through your radio equipment which could include the insulation between the windings on one of the isolation transformers. Other paths might include something flammable that could start a fire.
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Stick'em in the ground!
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by AI2IA on July 24, 2007
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I have a system of connected ground rods as part of my antenna set up. I also have one of these ground rods with a junction box on it and connectors. These connectors are all grounded directly to this rod both shield and center pins. This rod is connected to all the other rods.
If I anticipate an electrical storm, I manually connect all antenna coax to this junction box. All my antennas are then grounded away from my shack to multiple earth grounds.
I don't see how I can do more than get all my equipment away from all my antennas, and have all my antennas grounded to a series of earth ground rods via one convenient earth ground junction box. So far, so good!
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Lightning Protection
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by W3JXP on July 24, 2007
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Hi:
My tower is grounded with 3, 8' ground rods, one for each tower leg. The shield of each coax is bonded to the tower just as they leave the tower. The rotor cable is protected by a Polyphaser lighting arrester mounted on the tower where the coax is bounded. The coax runs underground in a 4" conduit to the house. Along the outside of the conduit runs a #6 copper wire that is grounded in 3 places over a distance of 50' with 8' ground rods. Were the coax enters the house there is another 8' ground rod. Inside the house there is a copper panel with Polyphaser lighting arresters bonded to it and to the ground rod outside the building. Also by code requirement the copper panel is connected to the AC power ground and the cold water pipes with #6 wire. This setup was designed by a fellow ham who owns a company that builds and rents tower sites all over the Central part of Pennsylvania.
So far so good. I do not disconnect anything and often keep operating while it storms. It may be stupid but I don't smoke or drink so I need some risk in my life.
John Passaneau W3JXP
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Lightning Protection
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by N4JBK on July 24, 2007
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So far I've put down 34 ground rods between 8 feet and 24 feet long. Ive put them off of all three legs of the towers, at all of the elevated guy points, at the service drop, the ham shack, and the load center. All are bonded together with solid #6 copper. I use #6 copper plus 1 inch wide tinned copper braid at the shack and at the tower legs. I use a 1/4 " thick by 2 " wide copper bar on the back of the desk to ground all the equipment to the rest of the ground system. I use polyphaser units on all coax entrances as well as antenna switches and rotor controls. I just picked up another 25 ground rods so its time to get hammering.
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RE: Lightning Protection
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by W4LGH on July 24, 2007
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AA4PB said..."The National Electric Code *requires* the station grounds to be bonded to the electrical service ground. One reason is exactly what you are seeing - a difference in potential between the grounds. If someone were to come into contact with the radio case and the case of something connected to the electrical service ground (i.e anything with a metal case and a 3-wire plug) he might receive a shock."
But you keep missing the fact that this room is totally isolated from the rest of my house. There is nothing for anyone to get across to shock themsleves, since everything in the room is on the same grounding system! It is virtually its own stand alone building,
but loactaed within the house.
73 de W4LGH - alan
http://www.w4lgh.com
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by AA4PB on July 24, 2007
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How is power fed into the room? Are all of the outlets on the walls powered from the isolation transformer and are their grounding pins tied to the radio ground in lieu of going back to the house electrical service panel? If not then you have two grounds inside the room.
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Lightning Protection
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by N4VNZ on July 24, 2007
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Speaking of ground rods, are the galvanized ones just as good as the copper-plated ones? They are about half as expensive, and it seems to me that corrosion of the copper might reduce the effectiveness of the copper rods even further than those that are zinc-plated steel. The reason I ask is that I am currently setting up a station at my new house (new to me, anyway), and have purchased a few of the galvanized rods to set up a ground system.
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by N5YPJ on July 24, 2007
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I haven't seen anything mentioned for open wire lines. I have a homebrew outdoor disconnect panel at the tower base. I basically keep it disconnected with the dipole grounded when not operating. My tower has two ground rods at the base. I'd like to protect my rig as much as possible, but really right now aim for keeping lightning away from the house and other more expensive goodies like computers & large screen TVs.
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RE: Lightning Protection
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by KE3WD on July 24, 2007
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>>>by DXSHORTWAVE on July 24, 2007
"We replaced the PolyPhaser units at our commercial HF monitoring and relay stations with Alpha Delta TT3G50 units. The internal capacitors in the PolyPhaser units started to fail when running just 1000 watts carrier. They were only 2-3 years old."<<<
Sound to me as this problem might have been solved by ordering up the next higher power handling Polyphasor unit. Am thinking that the duty cycle being so high, the units rated for the 1000W level were derated and over time, the capacitors failed.
But as long as you have some sort of good lightning protection, properly installed as per mfr's instructions, whether it be Alpha Delta, Polyphaser or ICE you are certainly in a protected position.
On the other hand, I've spec'd and used the Polyphaser stuff on both commercial and amateur grade equipments for years now without problem. I'm equally as sure that the same could be said for other reputable products.
.
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RE: Lightning Protection
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by K0IZ on July 24, 2007
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My station is at 9000 feet in the Colorado mountains. Very frequent electrical storms, lots of near strikes. My antenna is a large wire antenna in the trees. Using the Polyphaser website and other info, here's my total lighting protection system.
House has three air terminals along ridge. Chimney has two. All are interconnected and brought down all four corners of house using #00 wire.
The house has a #00 wire circling the entire house, with about 16 8ft ground rods spaced around. The four down wires at the house corners connect to the circle of wire. Circle of wire is also grounded to the service entrance box and to the telephone ground.
The circle of #00 wire continues out to the tree (about 50ft away from house) which has ends of wire antenna. Goes up the tree to balun box. Grounded at base of tree also. Coax (actually Heliax) goes down from balun box and shield is grounded at base of tree. Heliax then passes through 3/4" aluminum flex conduit, which is buried. Conduit is grounded only at the house end to the circle of ground wire. The conduit creates a low-impedance coupling the heliax.
Balun box has gas discharge tube (2 in series).
Heliax enters basement wall, goes to Polyphaser protector. Ground wire to protectors goes back outside and connects to circle of ground wire. Station grounds are connect to protector.
Service entrance box has large surge protector.
Extensive, yes. But if you spent some time around all of the lightning here, you would want more than a ground rod or two. So far absolutely no damage to anything in house.
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RE: Lightning Protection
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by W4LGH on July 24, 2007
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AA4PB said..."How is power fed into the room? Are all of the outlets on the walls powered from the isolation transformer and are their grounding pins tied to the radio ground in lieu of going back to the house electrical service panel?"
Yes! The power in the room is totally isolated from the rest of the house. Remember that I built this house, so I had a seperate panel put in for the shack.
Power to the shack is fed from the main box thru isolation transformers to the shack box, so tying the
two grounds together would bypass my isolation. So electrically and RF wise, the room is virtually seperated from the rest of the house. It was a lot of trouble and expense, but easy to do while in the building process.
73 de W4LGH - Alan
http://www.w4lgh.com
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Lightning Protection
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by W4VR on July 24, 2007
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I took a direct hit a couple of years ago...caused $10K of damage inside the house. When I asked the insurance adjuster, who supposedly was an expert in the field, if there was anything more I could have done to protect my home, he replied, "it's been our experience that when you get a direct hit there is not much you can do to lessen the damage, surge suppressors, etc. don't do much for you."
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by KF4WXD on July 24, 2007
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If you do have a strike, the insurance adjuster is going to look at the isolated ground system in the shack, not bonded to the service entrance ground and find plenty of reason to deny your claim. Section 250 of the NEC requires that all grounding systems be bonded together. Does power come into the shack? is there a ground on the circuit? Then there is a possibility for a ground loop. Get a piece of #4 bare copper wire from you local big box hardware store and bond the systems together. It's not just a good idea, it's the law.
Russ - kf4wxd
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RE: Lightning Protection
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by AA4PB on July 24, 2007
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Sounds like you have a well thought out system, Alan. Having everything on a seperate panel powered via an isolation transformer certainly makes a difference in grounding requirements.
For the average ham who's equipment and outlets are not isolated from the rest of the house the NEC required bonding of grounds does make sense.
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RE: Lightning Protection
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by AA4PB on July 24, 2007
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WXD: From his description I think what he has is classified as a "separately derived system" which allows for independent grounding in most jurisdictions.
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RE: Lightning Protection
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by KB9CRY on July 24, 2007
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I haven't seen anything mentioned for open wire lines.
ICE has arrestors for open wire lines.
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RE: Lightning Protection
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by WB2WIK on July 24, 2007
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Good insurance.
Make sure premiums are paid on time and the policy covers lightning damage (they all do, that I've seen).
Try not to be on the telephone when lightning strikes.
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RE: Lightning Protection
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by KF4HR on July 24, 2007
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I have two feed-through panels where I disconnect my antenna feds, rotator and control cables; one at the back of the house, and another where the cabling enters my shack. I also have polyphasers on each cable, out at the base of the tower. The polyphasers are securely attached to a ground buss which are tied to four 12 foot ground rods around the base of the tower. During storms I disconnect the AC and phone lines as well.
It is a pain to disconnect & reconnect everything? Yep! Is there extra loss in all the extra connectors? Yep, some! But after being hit twice, and going through the major insurance hassles of getting items replaced, I feel the extra precautions are well worth it. In my case every damaged piece of equipment had to have a manufacturer survey done to prove the damage was from lightning; washing machine, garage door opener, stereo, tv's, vcr's, computers, house intercom, etc, etc. So yes, I feel the extra precautions are well worth it.
I get a chuckle when I hear someone say they flip their antenna switch to 'center position' to ground their shack, or disconnect their coax "in the shack" and toss it aside.
Lightning travels across miles of free space. How hard do you think it would be for that energy to jump across the gap of an antenna switch, or across some metal object or wiring, to find a place to neutralize itself? Believe me, not very hard at all.
KF4HR
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by N9FE on July 24, 2007
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For open wire lines you can use a knife switch to ground or like i do banana plugs, pull them out of the tuner and plug then into the ground, very easy, And yes they do make lightning protection for open wire lines..
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RE: Lightning Protection
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by NB3O on July 24, 2007
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"separate panel powered via an isolation transformer"
I did something similar. Had the shack in a single-wide 100 feet from the house, with two 10kVA dry isolation transformers at either end, their grounds completely floating. The house had its NEC "250" safety ground rod, the antenna field had its 47 eight foot rods with 2-0 cadweldeded onto them to the antenna bulkhead panel.
Lightning hit the line neutral down the road and shorted primary and secondary windings together on both transformers. Let all the smoke out of the TV, microwave oven, refrig compressor, etc. The insurance went up about 20% after that claim.
We now have 2-0 cadwelded from the antenna field straight into the ground bus in the main service panel..........ten years later, dozens of line-neutral hits and a few tower direct hits, no more smoke (or insurance claims).
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RE: Lightning Protection
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by KB9CRY on July 24, 2007
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I'm gonna comment on snippets from some of the replies:
"I also have polyphasers on each cable, out at the base of the tower."
The only potential problem with this setup is that you may get enough energy induced in the section of cables between the tower and the shack. The best location for arrestors are on the cables just before they enter the shack.
"pull them out of the tuner and plug then into the ground"
The potential problem here is that you may allowan energy surge and more horribly a direct strike energy into the house where it may choose to jump off the wire to a different ground source (and starting a fire at the same time). The best place to shunt strike energy to ground is outdoors and not allow it into the house at all.
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RE: Lightning Protection
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by VE6XL on July 24, 2007
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Although there are degrees of protection, the basics are pretty standard:
-Bonding all grounds
-Single point ground within the shack
-Utilize a grounded bulkhead where cables enter building
-Surge suppression measures througout
As already mentioned Polyphaser has some excellent resource material, even if you decide not to use their products: http://www.polyphaser.com/technical_notes.aspx
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RE: Lightning Protection
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by W4VR on July 24, 2007
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kf4wxd said to bond everything to the service entrance if you have multiple grounds.
If your shack is in the vicinity of the service no problem. However, if your shack is located on the other end of the house and you run #4 wire to the service entrance from the equipment/ground rod, there will be a potential difference between the two ground points and you may suffer damage in the event of a lightning strike. When I took the hit two years ago, the adjuster was looking for evidence such as burnt coax, etc....he never asked about grounds because of the nature of the strike.
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Lightning Protection
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by DXSHORTWAVE on July 24, 2007
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In checking with the service department of a major equipment manufacturer, I found out approx 90% of lightning damage is NOT from direct hits, but from induced voltage from lightning discharges as much as a mile away from your antenna. Coax protectors and protected coax switches do an excellent job in by-passing these surges. Direct hits are an entirely different matter, but we wouldn't want our gear to go in to service because a distant surge popped the PIN diodes or MOS type devices in the front end of the receivers. All protection devices have their applications and can be very effective if installed properly.
This thread talks alot about direct hit protection, but remember, 90% of the damage is from distant voltage coupling to your antenna. Effective grounding techniques AND gas tube protectors should ALWAYS be used together!
Our stations are up 24-7 and we know what can happen, even with a "little" voltage spike of 3 kV at only a few mA of current. We've measured them on our storage scopes. They CAN and DO blow front end components that are without protection.
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Lightning Protection
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by N6JSX on July 24, 2007
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I wish some of you would get real - Polyphasers ONLY work if connected to a solid ground system that is sized big enough to adequately redirect the lightening energy from your shack to the ground. The problem is a Pholyphaser ground system is "unreal" to a normal HAM's budget and few HAM's have enough property to install a Polyphaser dimensioned system!
PolyPhaser didn't work for my last week when I took my first ever hit. It came through my AC system and took out many of my HAM/Test equipment and PC/Network devices.
The real problem is with Astron power supplies they have NO working spike/surge suppressors passing the spike into all my radios connected then killing the pass transistors killing the PS! Never thought Astron PS were so crummy but I lost two in two different locations; VS12M in the garage and RS35M in my basement with all my radios and repeater connected. (Antenna coaxes were all disconnected.)
I also HAD two UPS/surge/conditioning protection devices on my Network and the other covering my lab PC and RF Sig generator. Those items attached to these UPS's got nailed but my unprotected four PC's/monitors/printers (on the same AC circuit) are all fine - go figure.
The hit was very close to my home as my son KE6ATW's 2nd floor bedroom PC monitor required degaussing to view colors properly. Heck of an EMP near hit!
So don't get blind sided thinking Polyphaser solves all the HAM shack possibilities. There are far more AC/telephone lines to hit than HAM antennas.
N6JSX /8
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RE: Lightning Protection
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by KE4DRN on July 24, 2007
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hi alan w4lgh
Interesting subject !
Isolated (insulated ? ) ground in lightening protection application.
are the neutrals bonded to at the service panel to the ground ?
lot of stuff about isolated (insulated) grounding for sensitive equipment and hospital environment to reduce
emi/rf.
http://www.ruelsa.com/notas/tierras/pe30ig.html
73 james
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Lightning Protection
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by AI2IA on July 24, 2007
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I like to strive toward a goal of at least one contact a day, everyday. Bad weather, especially electrical storms, and strong wind and heavy rain make me decide against that day's goal. Emergency conditions are another matter, but most of us have no pressing need to operate in risky conditions. So it makes good sense to disconnect the antennas and ground the transmission lines rather than just leaving them to dangle in the air or rest on the ground, or leaving them hooked up to the rigs.
Antenna systems deserve a lot of attention. They are out there in the elements twenty-four-seven. Lightning arresters and static grounds need frequent checking, also, as do baluns.
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RE: Lightning Protection
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by N1LO on July 24, 2007
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I have an entrance panel in my shack window. It is connected to my grounding system (multiple rods and service ground) using 3/4" copper water pipe for a very low impedance path.
All feedlines come in through UHF bulkead connectors. Parallel feedlines terminate in short sections of shielded parallel line (two short sections of coax terminated with PL-259's).
On the inside, I have coax jumpers to the rigs, and shielded parallel line jumpers. The inside jumpers terminate with push-on PL-259's.
I made shorting plugs using PL-259's and short PVC handles (for insulation) that stay plugged into the bulkhead connectors on the inside, shunting all conductors to ground until I'm ready to operate. It's a snap to pull off a shorting plug, and plug the desired rig into the desired antenna connector.
The rotor cable is shielded, and terminates in an automotive trailer connector, which is mechanically locked into a cutout of the panel. On the inside is a mating connector with all conductors permanently shunted to ground. The rotor controller has a short section of rotor cable with another mating trailer connector.
--...MARK_N1LO...--
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Lightning Protection
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by N4OZI on July 24, 2007
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Lightning Protection? Well, if you want to do what the pros do, then get a copy of Motorola's R56 standard. It is an amazing document put together by Motorola, which contains their standards in dealing with lightning among other things.
N4OZI
Allen Cutts
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RE: Lightning Protection
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by KB9CRY on July 24, 2007
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So don't get blind sided thinking Polyphaser solves all the HAM shack possibilities. There are far more AC/telephone lines to hit than HAM antennas.
Well good comment. Polyphaser and ICE ALSO make surge suppressors (no the Wally World ones don't cut it) for your AC lines and telephone lines as well as your computer network and cable modem lines.
Yes we've forgotten to mention that you need to protect your equipment also from surges via these lines.
High Maintenance?
Nada, they either work and reset themselves or they blow and you'll know it. My ICE devices are still in line and I don't do anything with them. Any above ground ground rod connections that use mechanical clamps do require periodic retightening.
And no a proper grounding system is not out of the realm of we normal amateur ops but you DO need to install it correctly and not leave out any element or get cheap charlie about it. I never disconnect and have taken plenty of direct and even more (as described) indirect strikes. I have the proof and these things do work. It can be done. Of course I have homeowner's and fire insurance just in case Mother Nature gets really pissed. It can be done and don't listen to the naysayers.
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RE: Lightning Protection
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by NA1Q on July 24, 2007
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Gentlemen, I have to say that there are some real good Ideas here. I'll add my 2 cents worth to the pot. I had several antennas at one time or another and the best thing I found was connecting both sides of the coax to ground. I did this with a 2" x 12" x 1/4" Copper bar with SO-239 sockets attached directly to the bar. The bar was grounded through a 4/0 Copper Welding Cable about 12 feet long fed through a Grounded 1" EMT Conduit and connected to a 2" Diameter Copper Ground Rod (compliments of the local salvage yard and the electric company) I had the bar mounted on a sheet of Marine grade Poly-Board. Over 13 years I had several close strikes, and the only damage was a computer modem a couple of years ago.
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RE: Lightning Protection
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by VK6AV on July 24, 2007
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LPGI & Affiliates advise:
"There is a difference between minimum design standards found in the National Electrical Code (NEC) and good engineering practice. The scope of the NEC does not cover lightning and there is not a hint of what Ground Potential Rise (GPR) is or does. Nor is GPR mentioned in Motorola's R56 current standard either! In fact, there is no code book or published standard today that relates to the engineering design of equipment locations to prevent damage from lightning strike energy. However, this type of information is available in the "Guide for Protection of Equipment and Personnel from Lightning", in ASCE's Journal of Performance of Constructed Facilities, August 2002, by E. Duckworth ."
More interesting info on their website: http://lightning-protection-institute.com/prevent%2099percent%20of%20damage.htm
Note I have no relationship with this firm.
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Lightning Protection
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by N0AH on July 24, 2007
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Spark gap devices or bleed off static resistors......if you want to stay connected 24/7, you have to nip in the butt at the antenna.
For the serious vertical, the spark gap is the way many old timers do it. Basically, you have a well grounded rod very close to the antenna, a few mm for example...that way, when the strike happens, or you get a big static hit, the generated spark crosses the over to the nearby ground rod minimizing feed back to your rig via the feedline. RF chokes are good too-
Bleed off resistors designed for static are ok but I often find the wire cooked between the uninsulated base of the vertical and ground rod after any nearby by or close T-Storm.
Bottom line, Ham radio is a great Nov-Mar hobby (-:
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Lightning Protection
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by AI2IA on July 24, 2007
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You don't need any $75 Motorola book or fancy gadgets for lighting protection. Use common sense. Put up your antenna in a sane location. Use ground rods generously, and disconnect and ground your transmission lines way ahead of an approaching thunderstorm.
Now if your house and your ac lines are a problem, that is a totally different matter. Consult a local lightning protection company.
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RE: Lightning Protection
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by K9KJM on July 24, 2007
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Yes, ALL grounds NEED to be BONDED together. No exceptions!
To have two 10 foot ground rods that are NOT bonded together is much worse than having only one!!!!!!
The proper bonding of grounds is the single most important part of lightning protection.
As mentioned, The actual devices, (Polyphaser, I.C.E., etc) are far down on the list of things to have.
It sure is NOT beyond the average ham's ability to properly protectd a station from DIRECT lightning strikes! It may take some effort and time, The amount of money required depends on how good you can "scrounge" used copper wire, Copper roof flashing, etc. Years ago it was a simple matter to go to your local utility and get used ground rods (complete with the industrial clamps) for free, Or at most a contribution to the crews beer fund. Nowadays it is rougher to get those types of deals, But they are sill out there IF YOU LOOK and ASK.
To simply say "insurance" is the answer is silly. Insurance does NOT protect your own, Or your familys personal safety! I much prefer to spend my "insurance" premiums on a PROPER protection system!
I live on a hill with tall (200 foot, 120 foot, four 65 foot towers, and take direct lightning strikes most every storm, With NO damage.
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Lightning Protection
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by WB6MMJ on July 25, 2007
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Years ago I took a hit to one of my antennas. It came down the coax, arced to ground in at least two spots, splitting the coax in the process. It came into my house blew out the light bulb and some parts of my 4-1000 amp. and took out my scanner. It took out my low voltage components in my repeater. It blew out my house fuses, the old screw in type. It tripped my neighbors breakers and got me real good. My arms were numb for hours and my ears rang for the rest of the day and night.
I learned that lightening can do some really weird stuff. It doesn`t always stop when it hits ground.
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Lightning Protection
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by WV0H on July 25, 2007
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Since I get on so infrequently, I disconnect all radios from every conductor of electricity, meaning the antenna, all accessories, the mic, everything including the ground and scoot the radio forward about 6 inches to provide a nice big air gap behind the rig. The ARRL or somebody did a study of very high ESD/lightning on radios that were "unplugged" in a screen room and it really revealed that when your radio is totally disconnected from any conductor, that it survived the electric shock because of the Faraday Shield that the metal case of the radio provided. Sometimes I went a step further during the summer and when I lived at 9000 feet, I would put a metal cap screwed over the antenna connectors on the rig to provide extra shielding (5/8 x 24 thread size for UHF and type N connectors).
As far grounding, and again, 9000 feet, 30 foot tower, very poor ground, rohn 25, nine-ten foot 1/2" ground rods total, 3 at the tower base and 6 extending in a radial fashion all tied together with #4 & #6 copper various configurations. And here is another controversial subject, I firmly believe, after 15 years in the two-way radio field and study of lightning, a very well grounded tower with a SINGLE very well pointed (a 4 inch taper to a needle point) ground rod at the top pointing up, provides the best protection to bleed off the charge that tries to build up on a tower.
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Lightning Protection
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by W4MEC on July 25, 2007
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Another item that is overlooked is relying on tower sections to be your down conductor. Tower joints are not low ohm connections, at least to lightning. A down conductor should be run from the top of the tower to the ground system, bonding the tower sections as you go. An air terminal at the top would be an extra benefit, of course bonding it to this same down conductor. With no air terminal, antenna booms and masts should be bonded along with a bond around the rotor. Route this grounding down conductor along on leg of the tower and all other cables at a point as far as possible from this leg.
Buried mechanical connections are not allowed by code either. A buried ground connections has to be exothermically welded (Cadweld). A mechanical connection can be used if it is accessible for a routine evaluation of its integrity. Normally this would be found in some sort of plastic or concrete box where you could inspect and tighten it. I just used a flower pot, and put a rock over it.
Low resistance ground is the key, and it is not unusual to have to drive many rods to get this number. For the homeowner a good system is almost impossible to afford. I've seen one comm building with one tower cost $20,000 just to install a proper ground system with an acceptible ground resistance of 10 ohms. Remember that Ohms Law dictates what kind of voltage you are going to see on a strike. A 60,000 ampere strike on your poorly installed and bonded lightning protection system that may have 100 ohms of ground resistance will have a 6 million volt spike to pass around your shack before it dissapates.
A direct strike is always bad news, and like one commenter said, it might be best to leave home if you are that worried.
Charlie in NC
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RE: Lightning Protection
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by WA8MEA on July 25, 2007
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I learned this from an Elmer of mine many years ago. This same gentleman told me of the day lightning came down his coax, and danced around his shack! (He, too....lived in Florida.)
He told me to disconnect the antennae and place the ends in glass jars.
Now someone please explain this concept to me, since he didn't.
73, Bill - WA8MEA
http://HamRadioFun.com
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RE: Lightning Protection
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by K9IUQ on July 25, 2007
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I am ham that lives on a high hill and has been hit by lightning and was home when it happened,and believe me it is scary and will change your thinking about lightning.
There is only 2 ways to 100 percent protect yourself:
1.Disconnect all equipment, put in original boxes and set on a shelf out of radio room.
2. Get good home insurance.
Before I got hit, I only did #2.
By the way, my antennas didnt get hit, a cedar tree in my yard did. It went into the ground and hit my telephone line.The charge went to my dsl modem to my computer. Yes I had radios hooked to computer.
Stan K9IUQ
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RE: Lightning Protection
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by AA4PB on July 25, 2007
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"ends in glass jars"
An old ham's tale. Lightning has traveled many miles through the air to get to your antenna. Does is sound reasonable to think that a thin layer of glass is going to stop it dead in its tracks? Have you looked at the outer insulation on a piece of coax? The lightning would just burn through it even if you could insulate the connector at the end. Giving it a low impedance path to ground is the only way to keep the voltage low enough to prevent damage.
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RE: Lightning Protection
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by AA4PB on July 25, 2007
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"Disconnect all equipment, put in original boxes and set on a shelf out of radio room"
Still not 100%. The house may burn down and damage the equipment :-)
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RE: Lightning Protection
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by KB9CRY on July 25, 2007
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Another item that is overlooked is relying on tower sections to be your down conductor. Tower joints are not low ohm connections, at least to lightning. A down conductor should be run from the top of the tower to the ground system, bonding the tower sections as you go.
I disagree. The tower joints are metal to metal and will have no problem conducting the energy.
An air terminal at the top would be an extra benefit, of course bonding it to this same down conductor.
Air terminals have been proven that they don't do diddly.
antenna booms and masts should be bonded along with a bond around the rotor.
Again, metal to metal joints, will conduct no problem.
Buried mechanical connections are not allowed by code either. A buried ground connections has to be exothermically welded (Cadweld).
Right on.
A mechanical connection can be used if it is accessible for a routine evaluation of its integrity.
Actually what you'll find is that due to the thermal cycling from night to day, your clamps will start to loosen.
For the homeowner a good system is almost impossible to afford.
Nope, it can be done and doesn't cost tons. I have one and it works just fine. Yes there is a cost but a lot less than the equipment it's protecting.
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RE: Lightning Protection
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by KB9CRY on July 25, 2007
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He told me to disconnect the antennae and place the ends in glass jars.
Now someone please explain this concept to me, since he didn't.
Well, the glass is slippery and when the lightning bolt emerges from coax, it will slide around inside the jar. It doesn't come out the top because it wants to go to ground, which is down, and because gravity is acting on it pulling it down. So the bolt swirls around inside the jar until it gets tired and stops.
Makes perfect sense.
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Lightning Protection
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by N0AH on July 25, 2007
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Look at it backwards....you stand a good chance of getting a decent static blast off your uninsulated vertical no matter your ground system. I had a 4 square 1/4 wave 80M array with 240 1/4 wave radials, grounds, etc....N2IC and I were out playing with retuning one of the verticals when he got "zapped" by getting within a couple of inches of the antenna. A T-storm about 5 miles away was the most likely cause of the enviroenment allowing this to happen. Nothing life threatening but scared the ba-gessus out of us-
I say just use a wire with alligator clips to ground your antennas when not in use to a ground....it's not perfect, but its a start to begin getting in the right mind frame-
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RE: Lightning Protection
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by W4VR on July 25, 2007
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What I was told by my insurance company is that if it's power-surge related (i.e., lightning hits the power line then creates a surge in your AC power) they do not cover the damage. In my case I presented evidence to the insurance adjuster that one of my antennas was hit by lightning and they covered everything. By the way, I always insured everything I have with a replacement cost policy...it's not that much more expensive than a regular policy where they depreciate your belongings before they pay up. I'm not sure what the ARRL insurance policy covers in the event of a power surge.
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RE: Lightning Protection
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by W4VR on July 25, 2007
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First rule of thumb: check to see where the thunderstorms are using the internet NWS radar service. If the storms are within 5 miles of your QTH turn off your equipment and unplug the AC lines.
Second rule of thumb: Ground all of your antennas.
I learned to do this the hard way.
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RE: Lightning Protection
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by W4LGH on July 25, 2007
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N0AH said..."N2IC and I were out playing with retuning one of the verticals when he got "zapped" by getting within a couple of inches of the antenna. A T-storm about 5 miles away was the most likely cause of the enviroenment allowing this to happen. Nothing life threatening but scared the ba-gessus out of us"
Actually it probably had nothing to do with the storm 5 miles away at all. When you have that much wire in the air, a little dust gently blowing over the wire will create some serious voltage! No current, but the voltage can go way up, this is why you use a gas tube discharge device on your antennas. It will not allow the voltage to go but so high, then it arcs over. The voltage that shocked your buddy was way more than enough to blowup MOSFET devices in your radios.
When I lived in Virginia, I had a full wave 160meter antenna up. It would generate all kinds of voltage @ anytime. The worst was during a dry snow storm! As the snow flakes went past the antenna the would create a static charge, left un-grounded it would arc over in the pl259 within a few seconds. It those days I used neon bulbs to flash over. That particular day it was almost continously lit.
What everyone fails to remember, is that you don't need a storm to generate hi-voltages on your antennas. You also don't have to have a cloud in the sky for lightning to flash out of no where. This is where the discharge devices really shine, like the Alpha-Delta, Polyphasers, ICE etc. They are working 24/7, and even when you are operating. They don't protect your from a direct hit, but then all bets are off with a direct hit.
Next time the wind begins to blow and you don't have a discharge device in line, grab a hold of your PL259 and see what happens. It will make a believer out of you, real quick!
I only know of one radio that came from the factory with a gas tube discharge system built in it, and that was the Drake TR-7A. But then Drake was way ahead of their time.
73 de W4LGH - Alan
http://www.w4lgh.com
PS...let's lighten up on the glass jar thing, thats just one of those stupid tails that get passed around.
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RE: Lightning Protection
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by KC8VWM on July 25, 2007
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MAKE SURE you have insurance on your equipment! Don't assume your homeowners policy covers it.
---------
I always inquire how much the insurance company has paid out in claims related to lightning related damage before ever signing on the dotted line.
The insurance company that reflects the highest denied claims looses and the insurance company that pays out the highest amount wins.
All insurance companies keep a database of statistics related to types of claims they have paid out. Basically, if any insurance company can not provide you with these hard facts in the form of statistics, then I would suggest you take your business elsewhere as the insurance policy isn't worth the paper it's written on.
73 de Charles - KC8VWM
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RE: Lightning Protection
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by N5YPJ on July 25, 2007
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"ICE has arrestors for open wire lines."
Who's ICE? pardon my ignorance.
"Try not to be on the telephone when lightning strikes."
I've always heard don't use the telephone during an electrical storm. About three months ago we got an induced ring, a nearby lightning strike caused the phone to ring one short ring. Made a believer out of us, also one strike was close enough that it made one of our DirectTV receiver's circuits go SK - it wouldn't find the satellite signal.
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Lightning Protection
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by KI6LO on July 25, 2007
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My situation is somewhat different than most of the posts here. Living in the high Mojave desert of southern California, we don't experience the amount of lightning seen by those in the East. Our main problem here is static buildup cause by dry dusty winds blowing at higher speeds for days on end. Antennas elements make dandy static electricity generators. Bleeding off this static voltage buildup is important to prevent it from getting into the front end of recivers and such.
I have every tower grounded using multiple ground rods tied together with 1/4" solid copper wire antenna and bonded to the tower with same 1/4" wire. I was lucky to have a friend who had some electrical work done a few years ago and the electricians left a full big 24" diameter spool of the 1/4" wire. He didn't want it so I got it.
All coax feedlines are run thru Alpha Delta ATT3G50 surge protectors which are attached directly to each of the grounding networks within 24" of tower bottoms. Each rotor control cable is also run thru I.C.E. Rotor Surge Protectors Model 349 which is also bonded to the applicable grounding system for that tower at the base.
At the shack end, I have a pair of long ground rods tied together and to the AC electrical ground rod which is within 4 foot. A short length of 1/4" solid copper wire (appx 7 foot) is run from the ground rods to a buss bar at the back of the operating desk, which has all operating equipment grounded to that buss bar.
I leave everything hooked up most of the time. The only time I disconnect anything is if I know in advance we are expecting a large thunderstorm since I am located on the flat valley floor and my 2 towers are highest thing within roughly a 1/2 mile in any direction.
So far no losses due to static or lightning have occurred and I hope it stays that way.
Gene KI6LO
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RE: Lightning Protection
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by K9IUQ on July 25, 2007
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W4LGH says:
"When you have that much wire in the air, a little dust gently blowing over the wire will create some serious voltage! No current, but the voltage can go way up, this is why you use a gas tube discharge device on your antennas. It will not allow the voltage to go but so high, then it arcs over. The voltage that shocked your buddy was way more than enough to blowup MOSFET devices in your radios."
.........................................................
Al, I NEVER thought I would agree with or respect anything you have to say, BUT you are 100 percent correct on this. I use those dreadful "antenna tuners" and many times when a storm is in the area I have heard static build-up discharging (ARCING) in the tuner. Snow storms will do this too. If your tuner doesn't do this then your antenna ain't longer enough or high enough...........
I have used Alpha Delta antenna switches for many years. They have an replaceable arc plug builtin. I have had to replace 2 of these in 15 years because of storms.
One needs to protect against static discharge-buildup as well as direct lightning hits....
Stan K9IUQ
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RE: Lightning Protection
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by W4LGH on July 25, 2007
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N5YPJ said..."Who's ICE? pardon my ignorance.
"Try not to be on the telephone when lightning strikes." ~~ I've always heard don't use the telephone during an electrical storm. About three months ago we got an induced ring, a nearby lightning strike caused the phone to ring one short ring. Made a believer out of us, also one strike was close enough that it made one of our DirectTV receiver's circuits go SK - it wouldn't find the satellite signal.~~
If you have to talk, use a cordless phone when talking during a storm. On your DTV the storm probably took out the GASFET in the LNB located outside at the dish. As it has been said here, it doesn't take a strike to do damage to these devices!
ICE makes some really nice devices to help protect yourself and equipment. Remember an once of prevention
is worth a pound of cure!
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by N6AJR on July 25, 2007
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as to the guy who says why a single conductor down the tower is not necessary because the tower is metal. If you took an ohm meter from the tip of the tower to the base of it you would have several ohms of resistance, due to connections in the tower. Now when you are talking a gazillion volts, even a houple of ohms can generate a large voltage. for instant if youhave a 100,000 volt strike and 5 ohms of resistance, you could generate a lot of amps of current on the tower.
by using a real live lightning rod and a large cable or strap down the tower and have perhaps .05 ohms resistance you would only develope one one hundredth of the current, so it is good to put a lightning ground system on a tower if you are in a high storm activity area.
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Lightning Strike Example
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by KI6LO on July 25, 2007
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A first hand story of how lightning refuses to obey the 'rules'...
My parents live in SW Arkansas and a several years ago we had a lightning experience that was strange to say the least. The water tower across the road from my parents home was hit by lightning, which happens numereous times a year so nothing out of the ordinary. This time however the strike current flowed down the tower into the ground and followed the underground waterline, which by the way was metal but had been recently replaced with a PVC line. My parents are the first connection on the water line which goes to town 2.5 miles away. The strike flowed up into their yard killing a section of the grass as it went up to the point in the side yard where the buried water line intersected a buried electrical line (appx 18" of soil between the 2 'circuits') where the strike current 'jumped' from the water line into the electrical system and proceeded into the house and my fathers shack in another building. The strike blew out every electrical device in both buidlings and actually blew the telephone off the wall, across the living room and set the drapes on fire. Had my brother not been quick to think and yank the drapes off and out the door the house would have been done for.
Except for section of burned grass in the yard, a dead spot in the side yard where the water line crossed the electrical line underground (which took years to regrow), a set of slightly charred drapes and a toasted phone, there was no other tell-tale sign of a lightning strike. The insurance company replaced all the appliances.
The funny thing about the jump point in the path was the water line did NOT burst but the electrical line was charred and had to be replaced.
Lightning live by it's own set of unwritten rules!
Gene KI6LO
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I do it simply
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by KASSY on July 25, 2007
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1) Move to part of the country with next to zero lightning. Much of the west coast goes years without lightning.
2) Situate the ham gear at least 150 feet from the main house
3) Situate the antennas at least 100 feet from the ham shack.
4) Ground the heck out of the antennas...do not ground the shack. If lightning strikes the antennas, it finds an easy ground under them...and no useful ground in the ham shack.
5) Employ a very lightweight and long interconnect system between ham shack and antenna field. In my case, I transition from 50 ohm coax, to 50 ohm 5-wire transmission line, fabricated from 20 gauge wire, for 10 feet. Lightning will vaporize the ten footers and effectively disconnect the shack.
Twenty years ago, a ham I knew did it this way and sure enough...his tower took a direct hit, his "weak spot" in the tlines vaporized, and he lost no equipment, except for the now welded together sections of the tower.
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Lightning Protection
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by KC8VWM on July 25, 2007
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My cat who is notorious for generating static electricity is grounded to the shack bus bar just in case. :)
Yes, I ground everything using 1" copper straps bolted to a shack bus bar using stainless screws and washers (mechanical bond) to a length of 3/4 inch copper pipe mounted on my shack wall and it runs along the entire wall behind my equipment in the shack. The copper buss bar is also useful for mounting antenna switches on it too.
One end of the copper pipe is connected by mechanical means to a #4 copper wire that runs directly outside the shack to a 10' copper ground rod driven into the ground.
The shack ground rod located outside is also connected to the electrical mains ground.
The antenna tower has two ground rods installed and they too are tied into the same ground system outside.
I have also spread out and dissolved some water softener rock salt pellets around my ground rods. Not very friendly for the surrounding vegetation however I found a little topsoil and grass seed can always fix the grass much cheaper than replacing the equipment in the shack due to a lightning strike.
Recently, I heard a large bang that rattled the windows in the house. Looking out the window I saw cinders blowing from a tree located in my backyard. Upon closer inspection the next day I found out the lightning had blown a tree literally in half in my backyard.
This tree was located less than 30 feet away from a full sized 40 meter dipole. The shack equipment connected to that same dipole was completely unaffected by the nearby lightning strike.
Don't know what that means exactly other than the simple fact that a rather hefty lightning strike occurring less than 30 feet away from my dipole antenna didn't affect any of my shack equipment which was turned off but yet still connected to the antenna system at the time.
73 de Charles - KC8VWM
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RE: Lightning Protection
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by K9KJM on July 25, 2007
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The "old wives" tale stunt of putting coax ends in glass jars does help insulate simple static build up on wire antenna lines, BUT does less than nothing for a direct strike!!! In fact leaving ungrounded coax laying about anywhere, Including in glass jars is like leaving dynamite in your house!!!!!! The ONLY way to protect is to ground those coax runs. Either a grounding switch like Alpha Delta, Via a lightning arrestor like Polyphaser or Industrial Communications Engineers, Or screwing them to a grounded SO 239. (A very dangerous way to do it when a storm is approaching)
The idea to run a separate downconductor down a tower has been disproven many years ago. I tried that stunt in the early 1970's. Creates more problems than it "solves" Even a little Rohn 25 has PLENTY of surface area to provide a good low inductance path for lightning through it's legs. IF you run bare copper up a galvanized tower you have the problem with zinc/copper interaction (Bad) IF you run insulated wire problems are created with different voltages being created on the downpath. See the Polyphaser notes regarding this.
No matter what type of tower you have, Including very large commercial towers, There IS a voltage difference at different points on the tower during a direct lightning strike. In fact that is how lightning strike counters work, "Tripping" a counter from the voltage difference of 20 or so feet of the tower. Adding an extra wire conductor to that tower will not change that situation no matter how large the conductor is.
The series of three articles in QST magazine a few years about lightning protection was very good.
The final 3rd article on grounding is here:
http://www.arrl.org/tis/info/pdf/0208053.pdf
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RE: Lightning Protection
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by K9KJM on July 25, 2007
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The "trick" of adding rock salt to a ground field does in fact work well. K9STH has plans to build an "enhanced" ground system using old copper tubing, That is very similar to big buck commercial systems that use enhanced grounds.
There are many ways to do it, Drilling lots of holes in large diameter copper tubing and filling with rock salt is a popular one.
There are many brands of ground enhancement materials, "Terrafill" is one, Here is a link to instructions for another: http://www.sv-franklin.com/example.html
Using the enhanced materials is now the most popular way to ground commercial towers (Cellphone, Public Safety, etc who do NOT have the option to "disconncet" when dark clouds approach. Years ago, Drilling deep wells and then grounding the tower to the steel well case (That was filled with Bentonite clay) with Cadwelding was popular, But very expensive.
Flat copper strap from the tower to these enhanced grounds is the way to go when you cannot get a number of 8 foot rods driven in, Or have really poor soil for grounding.
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RE: Lightning Protection
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by K9IUQ on July 25, 2007
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"The "trick" of adding rock salt to a ground field does in fact work well."
.......................................................
I live in Redneck Country. Around here when a ham feels the need he says "I am going to water the ground rod."
I think it is a macho ham thing, better than watering a tree.
Some on my friends have even taught their dogs to water the ground rod. Its much like adding rock salt...
LOL
Stan K9IUQ
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Lightning Protection
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by KC0NYK on July 25, 2007
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After 35 years of practice as both an electrical engineer, linesman and practicing master electrician, [who, by the way, got hit by lightning on a fully grounded powerline system; an experience I DO NOT RECOMMEND], when it came time to design a grounding system for my own shack I choose to be pretty decisive. I placed a 35 foot coil of #4 bare copper in the base of the tower with two lines running up thru the concrete; bonding to the rebar and the tower base bolts by exothermic welds. I also ran GROUNDING radials away from the house buried approx 12 inches deep which are also bonded to the grounding matrix. I drove a 3/4 x 10' copperclad ground rod next to the tower and then tied all of the extended #4 wires to the tower base, then to the ground rod with no break or splice in these wires.
Then, I fabricated a weatherproof steel box with a bracket made from some old grounding bar materials [1/4 in x 3" x 12" aluminum bar stock] thru which I drilled holes which accept exactly SO235 female to female barrels with nuts. This unit is connected to the metal box and then to the grounding rod via a ground strap made of the outside braid of some old RG 213 copper without any break or splices. I run my coax cables into this box from the tower thru the splice barrels to provide grounding and then ran a #1/0 bare copper wire from this box to a bonding bar in the shack to which all the equiptment grounds are fed from the gear [transceivers, powersupplies, computers, tuners, etc.] This entire system is also connected by a discrete ground wire #1/0 copper to the primary electrical ground rod thus complying with the NEC and NESC Electrical Codes [since I am an member of the code committees of both books, I thought it would be in poor taste to violate the codes]. My rotor is fed via the same box by using an eight terminal NO [normally open] relay which is powered by 13 vdc which I supply to it from my power system which is protected by an AFCI circuit breaker feeding a GFCI receptacle in the shack to provide maximum protection on the AC side of the system. The main panel is also protected with a lightning protection system [about $50 installed] as well.
The premise is to provide maximum protection from a strike and at the same time allow my station to stay on line during storms when a SKYWARN net controller is really needed. The battery back up system is fuse protected as well from overcurrent. The point of the multiple lightning protecton radials is to take the current spike away from the station as quickly as possible and dissipate it.
I have designed several of these systems for other hams and so far no one has had any problems that we know of.
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RE: Lightning Protection
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by W4LGH on July 25, 2007
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KC0NYK said.."This unit is connected to the metal box and then to the grounding rod via a ground strap made of the outside braid of some old RG 213 copper without any break or splices."
The ground radials are a good idea, as there have been many studies that show lightning will hit ground and go off in 100 directions. Only problem I see with your grounding system is the Braid you are using. It has been proven that once exposed to the elements and starts to oxidize, that 1000's of diodes are created within the braid, which can have a varied effect on your system, from RF hotspots, to frequency division/multiplication issues, not to mention how many ohms off ground it could be. Would recommend losing the braid and replacing with some good solid copper.
73 de W4LGH - Alan
http://www.w4lgh.com
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Lightning Protection
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by WA4CYP on July 25, 2007
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Nice article, Alan. My "solution" is described at http://home.tampabay.rr.com/bushman/Lightning.htm and isn't too different from yours. I think the real point is to acknowledge the threat and do SOMETHING to address it. 73, Bill.
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Lightning Protection
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by K5AGO on July 25, 2007
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I had the opportunity to rebuild my shack this year during a home remodeling project. With several antennas on the roof of the house, I decided it was time to get serious about lightning protection. I consulted the Internet, several knowledgeable friends, and an electrical engineer at work who designed the lightning protection system for our data center. To start, I buried 7/16" diameter commercial lightning cable, a copper cable with a 65,500 circular mil cross section, at a depth of 24" around the perimeter of the house. At 15' intervals I tied the cable to 10' driven ground rods. At convenient tie in locations I ran the same cable to the roof to each of my antenna tripods and masts. When my buried cable passed the main AC feed into the house, I bonded my system with the main AC ground rod (most experts agree this is a mandatory item). Outside the shack I mounted a DX Engineering grounding panel filled with both Polyphaser and ICE lightening protection devices terminated to the buried ground wire. Next I connected a large ground buss in the shack to the external ground system with #2 copper. Every piece of equipment in the shack connects to the ground buss via 1" flat braid. External to the ground system, I added a whole house surge protector to my home’s circuit breaker panel. I hope my system is never put to the test although I do feel a direct strike is now less likely to set the house on fire. I still disconnect the coax cables from the shack equipment when not in use.
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RE: Lightning Protection
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by K9KJM on July 25, 2007
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W4LGH is correct. "Braid" is the wrong material for lightning grounds. (The ONLY time it is used would be where a ground line has to flex a lot, Like grounding a steel door to a steel door frame.
Flat copper strap is the way to go. This material can be obtained from upscale roofers besides the lightning protection supply companies.
(In fact before the prices of scrap copper went through the ceiling, Roofers would sometimes even toss the scraps of the copper roof flashing in the dumpster!!!!!!
Most home supply stores sell 6" X 10 foot long rolls of this copper at reasonable prices.
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RE: Lightning Protection
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by K9WQ on July 25, 2007
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I'd be very interested in hearing further discussion of Alan's idea of using wire mesh as a Faraday cage around the shack room in new construction. I'll be building a house to retire in next year, and this thread has been very helpful. Should I consider the Faraday cage?
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RE: Lightning Protection
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by W4LGH on July 26, 2007
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The faraday sheild started out in life to shield this room from RF either coming in, or going out. And it works well for that. Cell phones go dead in here, as do HT's! (grin) I then realized that it would also be
a big benefit with lightning. The copper screen is not cheap, and I imagine its even higher since I built this house 3.5 years ago. If it fits in your budget, I would certainly do it!
Now the following was sent to me in email, and is pretty self explanitory, so I posted it for him.
From KB5F...
Alan,
Can't post to eHam to save my soul. Lightning thread had all good concepts, logic and theory. Good points touching on the halo concept inside the building and multiple grounds or ground ring around the building, connected at a single bonded pass through, bonded to all building utilities at the same entrance.
Modern cell site type protection is based on low impedance grounding, the ability to flow the current to dissipate the charge, surge suppressing actual strike current OR impressed currents in ancillary systems (phone, electrical, etc. put there by "Cross talk"). A whole house surge suppressor takes care of the panel, but stray currents in multiple systems can again impress themselves before reaching the device. The rules for suppression is to place the device within 6 feet of the protected device.
A third concept to survival that I have not seen much in the thread is dissipation of the charge to begin with. It all goes back to Franklin and his lightning rod. On the one hand, we put a high pointed rod to snag the strike, 40 degree cone of protection, etc. On the other, behold, St. Elmo's fire indicating DISSIPATION of the negative cloud charge and the equal and opposite positive ground charge.
Several firms give written guarantees of no strikes to protected equipment. Essentially a high umbrella with spikes pointed skyward, the guarantees are
real. And expensive. I installed a porcupine looking bound stainless steel bundle of 25-50 sharpened 12" SS spikes at the top of the mast, cost was about $50.
I live in Houston where charts show that elevation and those number of thunderstorm days indicates on a swell chart that I should expect 2.3 to 3.2 hits per year. In 7 years, none to my knowledge. My only explanation to this is the porcupine. And I have scratched my head for those 7 years, not bothering to but the box of polyphasers in line or installing the ground loop. Plain stupid I guess, or flat dumb luck. Maybe I am really wanting to see blue ball lightning in the shack.
73,
KB5F
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Lightning Protection
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by N4FOZ on July 26, 2007
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When my new home was built, I gave a lot of thought to lightning protection, as I live in Florida.
I bought the expensive Polyphaser book and actually spoke with the Chief Engineer about the project. I probably won't remember all I did, but here is are the highlights:
The home itself has 2" metal strapping, every 3', across the home, going to a common ground, with 58 separate grounding stakes surrounding the home. This system is also common bonded to a perimeter steel rail system that surrounds the home and is bonded to the strapping and ground rods.
Phone: Buried, with protectors and a separate ground line bonded to the electrical system, as the two poles are a few feet apart. The house grounding is also bonded.
Power: Bought the Leviton whole house Surge System that interfaces with the power meter. Also use the usual UPS systems in the home (6), but use Isobar Surge Protectors (the $25k guarantee jobs) for the Ham Shack.
I have a 52' tower. I sacrificed one section to bury it 8'. At the bottom, there is no concrete, but instead there are several connected radials fanning out into the earth around the tower. On top of that is gravel and then concrete. The idea is to let the energy pass beyond the concrete, decreasing concrete heating during the strike.
At the bottom of the tower is the main ground, which is heavy copper. The copper is bonded to all three legs, but the main exit point wire goes to saltwater and about 30' of wire is 15' under saltwater.
Each piece of coax runs down the tower, then is terminated in a metal plate, with a double female SO-239, using the theory that electricity travels on the shield side of the coax. That plate is specifically grounded in copper to the legs and then run to the main ground point on the tower. The coax then runs to the house, underground in non metallic conduit.
The Ham shack itself has all common point grounds going a short distance to it's first ground rod. Each wire has it's own clamp, above ground. That rod is then duplicated 2 times the distance, for a total of 3, to the aforementioned tower grounding point.
In any event, I still unplug all the equipment during a storm. I have had one strike I witnessed, with all equipment running, but had no damage.
Guess I was lucky.
Worried about static, I bought a Bengal Cat, that has a pelt and not long fur..
N4FOZ
Jacksonville, FL
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Lightning Protection
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by KG6OMK on July 26, 2007
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You wrote: "ll of this is bonded together creating a faraday shield around my shack"
A Faraday cage needs to completely enclose the area on all sides. You have a shield of some kind but "faraday" refers to a very specific kind of shield. The Faraday shield can have small holes but these need to by very small compared the wavelength that you are trying to shield. I hate to say it but if you don't have a tight fitting door that makes good electrical contact all around it's edges with the screen in the walls and if the floor is not screened. For faraday's effect to occur it must be possible for current to flow in a loop around the enclosure in any direction.
I've worked in some of these screened rooms and been
involved in the construction of one. Let me tell you
they are hard to build and you really have to test them to know if they work. Poor electrical connection between the panels and the
gaskets on the door are points of failure.
I'm not really sure what 1/2 of a faraday cage would do. It would likely attenuate RF coming through the wall
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RE: Lightning Protection
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by W4LGH on July 26, 2007
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Well it took awhile, but I knew someone would have to come out and be very specific & technical about my "SHIELD" , which is completely enclosed, except for the door, which I think is more than close enough to do what it does. As for the floor, it is bonded to the re-bar in the concrete, which is completely bonded to each other and then bonded to the house ground system.
WEBSTER says....
"Faraday shield (′far·ə′dā ′shēld)
(electricity) Electrostatic shield composed of wire mesh or a series of parallel wires, usually connected at one end to another conductor which is grounded. Also known as Faraday cage; Faraday screen."
So according to this...I think I am close enough.
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by KC8WUC on July 26, 2007
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I start by grounding the antenna, connecting an ICE protector close to the antenna mast if possible, run this to ground using #4 solid copper wire. I have a 10' ground rod sunk into the ground using a jackhammer (don't dig a hole). This is also connected to the perimeter ground around my house. I am unable to make this ground all the way around my house due to a concrete driveway being next to the house, although this is a fairly complete path. I have 10' ground rods driven in every 8', connected together with Cadweld, and #4 solid copper wire pigtailed to 1" copper ribbon. Inside my house is my SPGP, where I have lightning protection gas tubes and surge protection devices for my power supplies mounted (Zero Surge). This is also bonded or connected to my electrical service via the same ground rod in my basement. My system took a lot of doing and money on my part due to the fact that I had to have the utilities located by a locating service; as a matter of good grounding, you need to bond everything that is metallic that comes within 3' of your ground rods, so I needed to avoid placing ground rods near the underground gas, water, sewer lines coming into my house. All of my equipment is grounded to a Harger grounding strip which is connected to my SPGP, which is very close to my desk where the radios sit. My set up is not very elaborate and is probably less difficult to set up than most given the fact that I just use an IC-7000, rely primarily on a High Sierra antenna and a Ventenna (I prefer the minimalist approach).
73's
Michael
KC8WUC
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RE: Lightning Protection
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by KC8VWM on July 26, 2007
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by K9WQ on July 25, 2007
I'd be very interested in hearing further discussion of Alan's idea of using wire mesh as a Faraday cage around the shack room in new construction. I'll be building a house to retire in next year, and this thread has been very helpful. Should I consider the Faraday cage?
--------
Incidentally and contrary to popular belief a Faraday cage doesn't have to be perfectly constructed to protect you or your equipment from lightning damage.
This is because there are basically two types of practical applications for Faraday cages. One is designed specifically for RF applications and the other one is specifically designed for lightning protection applications.
For example, a Faraday cage used for a specific RF application is the shielding inside the coaxial feed line you use to feed your antenna.
An example of a lightning based application for a Faraday cage is a modern day automobile.
Many people believe the misconception that since the rubber tires of the automobile are insulated and don't touch the ground, then this must mean a nearby lightning strike will not harm them.
However the reality is that lightning has just traveled a few miles through the air and trust me, a few inches of rubber isn't going to stop lightning from reaching it's final destination.
So in principle and similar to Alan's ham shack, It's actually the construction of the surrounding metal on the automobile which protects the occupants and creates a Faraday effect that affords them this protection from lightning.
Basically, anything metal can be used to construct a Faraday cage in principle. Even Micheal Faraday himself shielded an entire room coated with foil
to conduct his "shocking" experiments.
Another example of a practical Faraday cage is the wire mesh used to form plaster walls inside your home. The only thing missing is the ground wire and your basically in business.
Like a coaxial shield a Faraday cage can be specifically engineered, designed, tuned and constructed to ensure no RF signals from a given frequency range can ever leave the room or building either! I suppose this might be useful if you don't want your kids text messaging using their cell phones in their rooms all day.
So depending on your budget, engineering skills and other considerations it's quite possible to construct the "ideal" Faraday cage which provides the benefits of both lightning protection "and" the ideal RF shielding environment at the very same time.
However, I would strive to design it for the lighting protection end of things and cross my fingers that it provides a certain level of RF shielding ability at the desired radio frequency ranges without having to break out the calculator because I can't exactly readjust the ham shack walls to fit the dimension of the calculations.
73 de Charles - KC8VWM
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RE: Lightning Protection
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by KC8VWM on July 26, 2007
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I should add that when designing your ham shack that a Faraday cage that is in principle constructed of a solid metal conductor such as a copper sheeting is a more effective shield against EMP and RF applications than a wire mesh would demonstrate.
However an ordinary wire mesh similar to an aluminum window screen is more than adequate for providing adequate protection from very high voltage pulses located outside the shielding as demonstrated in this interesting video demonstration:
http://www.youtube.com/watch?v=mUWxYesR5Wo
73 de Charles - KC8VWM
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RE: Lightning Protection
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by W4LGH on July 27, 2007
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There has been a lot of good ideas posted here, and one thing is certainly clear...there is NO one magic solution for lightning protection. However it does take more than just running a ground rod and tying everything to it.
One thing that hasn't been discussed is what they call a lightning loop. It's about 3 turns in a 6" diameter circle in your coax. This is placed at the point of entering your shack. Several studies show that it does offer some protection. Again, more so with static discharge, as I think its a moot point on a direct hit.
I do believe in gas tube discharge systems and strongly urge all to use them, whatever your favorite brand is, or your budget can afford as some are better than others, but they all work! More damage is caused my static discharge than direct hits.
Thanks for all the posts and emails....
73 de W4LGH - Alan
http://www.w4lgh.com
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Lightning Protection
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by N4FOZ on July 27, 2007
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http://www.youtube.com/watch?v=bZwlD-Z0zmE&mode=related&search=
Here, folks, is a Faraday Cage Demo. on YouTube that will get the point across.
N4FOZ
Jacksonville, FL
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RE: Lightning Protection
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by W0IPL on July 27, 2007
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A more realistic summary:
http://www.lightningsafety.com/nlsi_lhm/lpts.html
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RE: Lightning Protection
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by W4VR on July 27, 2007
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Looping your coax at the point of entry sounds like a great idea but contrary to electrical theory it does not work very well. I've always looped my coax (3 to 5 turns) and all three times I got struck by lightning (they say things come in three's) there was considerable damage down the line...but you could see where the coax had been destroyed at the feedpoint and the dialectric and center conductor had a carbon coating all the way into the radio shack. The center conductor in the coaxial loop portion got so hot due to high current that it melted the dialectric in the loop.
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RE: Lightning Protection
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by AA4PB on July 27, 2007
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"Looping" the coax for lightning purposes does not mean making multiple turns. It is recommended that coax coming off the bottom of the tower make a "U" shaped bend before heading to the shack. This is in hopes that any lightning currents flowing on the coax will flash over to the ground at that point rather than following the conductor into the shack.
A "U" shaped drip loop is often made at the building entrance in order to provide a low point for rain water to run off. Water running down the long run of coax would have to turn and run up hill in order to follow the coax into the building.
Multiple turn coils of coax is sometimes used to provide an RF choke in an attempt to minimize RF currents flowing on the outside of the shield. Such RF currents could be caused by an antenna load that is not properly balanced or coupling between the antenna and the coax (i.e. coax running parallel to the antenna element).
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RE: Lightning Protection
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by WR8D on July 27, 2007
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I have all the rigs strapped together via a main "very large" copper strap. The same strap material runs right out of the shack to a ten foot copper ground rod. The tower is grounded about the same way only via a very large copper cable to a ten foot ground rod.
I don't trust the polyphaser stuff. Lightning has jumped those things at my repeater site and still cooked electronics. I've seen the phone cable running from the polyphaser burned black from the lightning surge...and the pholyphaser be perfectly ok and it was in direct line and hooked up properly to stop the strike.
Those little power strips with lightning protection built in that we can get at wall mart are the only things that have saved the repeaters here. It cooks them good but the surge does'nt get through to the delicate controllers etc.
I also have those same type of power strips all over the shack.
73 have a great weekend.
John WR8D
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Lightning Protection
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by WA5MZI on July 27, 2007
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I'm a little surprised to read that people are wiring the rebar in the concrete base of their tower into their ground system, or that they are in other ways running their ground connection through the base of their tower. I recall reading somewhere (ARRL Handbook or Antenna Handbook?) that this is definitely a no-no. Do you want lightning blasting the base of your tower to smitherines?
Steve Westfall
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RE: Lightning Protection
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by W4LGH on July 27, 2007
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I had a commercial tower up @ 300' with the first 8' of the tower in the concrete base. The tower was grounded via large copper strap to multi 10' ground rods, and tapped on the tower at various locations and heights. Over the course of 30 years, the tower took many direct lightning strikes. The tower was loaded with many commercial repeater systems, both VHF and UHF, plus several 800mhz paging systems. In 30 years, I lost one VHF system, and it knocked out the alarm system in the blockhouse 1 time. Didn't think that was to bad a record. The one thing that I learned with towers, was to have a lightning rod on the top, securely attached to the tower, and mount your antennas on the sides, below the lightning rod.
This is harder to do with Ham towers, but if I ever put one back up, I WILL have something stuck ABOVE the beam, going directly to ground.
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by W4KVW on July 27, 2007
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I disconnect "EVERYTHING" from OUTSIDE the shack when not in use with quick disconnects as well as I unplug EVERYTHING in the shack & I use "ZERO" grounding on my home station!WORKS for me!
Clayton
W4KVW
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RE: Lightning Protection
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by KC8VWM on July 27, 2007
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I disconnect "EVERYTHING" from OUTSIDE the shack when not in use with quick disconnects as well as I unplug EVERYTHING in the shack & I use "ZERO" grounding on my home station!
-----------
So does this mean when lightning is near you take down your tower and remove your antenna too?
It would take me a good hour or so to disconnect all my rigs from my antennas, unplug them from the electrical outlets and discconect my antenna switches etc, etc...
Seems like it would be a whole heck of a lot easier just to install a proper ground system wouldn't it?
73 de Charles - KC8VWM
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Lightning Protection
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by AB7E on July 27, 2007
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"WA5MZI: Do you want lightning blasting the base of your tower to smitherines?"
That's a ham radio equivalent of an urban legend that seems to get perpetuated primarily because it sounds so extreme, not because it has the slightest basis in fact or theory. You might want to read some of the earlier comments in this thread, or search the TowerTalk archives, or check the Polyphaser website or any of several other websites that have debunked this myth. You can check (as I have) a zillion other references and you won't find a single substantiated case of a tower base exploding because someone ran a ground connection through it. You might (as I did) find a couple of instances where lighting blew up some concrete, but not directly because of any ground connection running through it. The instances I found were not tower bases, and they blew up precisely because they DIDN'T have a good path to ground through or around them.
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RE: Lightning Protection
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by WA5MZI on July 27, 2007
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AB7E: I DID read all the comments made prior to mine, and I also recorded the URLs recommended in those comments referencing the articles that you mention with the intent of reading those in the near future. I raised the issue of channeling the lightening discharge through the tower base because no one had yet raised it. Since it has been asserted in respected ham publications, it seemed appropriate to bring it up. Now we have the opportunity to address the issue and debunk it if indeed it is a myth. I look forward to reading the additional references on the subject.
Thanks for your comments.
Steve Westfall
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RE: Lightning Protection
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by K9KJM on July 27, 2007
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WA5MZI: The FALSE ham "old wives tale" of damage to concrete has been DEBUNKED right here on Eham, And on QRZ many times.
http://www.comm-omni.com/polyweb/ufertower.htm
And
http://www.psihq.com/iread/ufergrnd.htm
(AND I could go on and on and on and on with links)
Again, It is GOOD to bond your rebar in concrete to your grounding system.
THINK it over! ALL towers are ALREADY grounded in concrete via the "J" bolts, Section IN the concrete, etc! (Except insulated AM broadcast towers)
NOT ONE documented case of damage to concrete has ever been shown for a properly grounded tower!
Just because someone not qualified to do so made a comment in some magazine does not make it true.
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RE: Lightning Protection
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by K9KJM on July 27, 2007
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The "ONE time" damage refered to in the Polyphaser site in the Nevada desert was on a tower that was NOT grounded!!!!!!!
This whole subject was resolved long ago, I started bonding tower grounds to rebar in concrete in the early 1980's on commercial height towers.
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Lightning Protection
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by K4DTC on July 27, 2007
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My tower is a over 200 feet from the shack. The tower is a 55 foot crank up, and with the tower base and mast, my tribander is at about 68 feet. Each leg of the tower is grounded with three 8' copper clad ground rods, each 16 feet apart in a radial pattern, using #4 solid copper wire. There is a water proof enclosure with a copper bulkhead at the base of the tower with a Polyphaser attached to it. The coax shield is also grounded at the tower base. The coax runs throught the trees to another water proof enclosure at the outside of the shack. Inside the enclosure at the shack is another copper bulkhead. There is an ICE products arrestor for the rotor cable, and and ICE products arrestor for the coax in the enclosure at the shack. The coax shield is grounded a second time outside the shack. The copper bulkhead at the shack is grounded all the way back to the electric service entrance, with 8' copper clad ground rods every 16 feet, using solid #4 copper wire. The station ground runs back to the copper bulkhead outside the shack. Due to the distance, the tower ground is NOT connected to the ground outside the shack. So far, no problems with lightening, and excellent reception. Any opinions as to whether haveing the Polyphaser and ICE products arrestors in the same coax line? I am hoping that one or the other will keep my station from getting fried without too much loss. By the way, you can sometimes get lucky and find some EXCELLENT deals on EBay for this type of equipment. I was able to get comercial grade copper bulkheads, water proof enclosures, and coax grounding kits for almost nothing.
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RE: Lightning Protection
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by KC8VWM on July 27, 2007
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If the theory behind electricity is that it is supposed to flow like water and if our antenna should get struck by lightning, then why is it that the electrons from that lightning stike doesn't spill out of the coax into a room and drown us?
:)
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RE: Lightning Protection
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by K9KJM on July 27, 2007
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K4DTC: Your tower and radio room grounds are ALREADY bonded together via the coax shield! You really should have a much better buried ground wire or strap bonding them!
The protection is from your grounding and arrestors at your single point ground by your radio room. As long as you have the coax shields grounded at the base of the tower, The arrestors out there mean very little in the overall protection scheme.
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RE: Lightning Protection
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by KC8HXO on July 28, 2007
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C'mon folks. Lightning is looking for a way to GET TO GROUND. Snip off the ground terminal on your power supply, computer cords, and all that. Insulate all your stuff from the ground, and lightning won't even TRY to hit ya. ;-)
PS- pay up on that insurance, just in case I might be wrong. (again).
Greg, KC8HXO
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by WA5MZI on July 28, 2007
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K9KJM: Thank you for the additional URLs referencing the articles on Ufer grounding. They were very helpful. But you seem to be laboring under the impression that I was seeking to perpetuate the myth. Please note that I already indicated in my reply to AB7E that I appreciated his references to the TowerTalk archives, the Polyphaser website, etc., where the misinformation is corrected. I always welcome it when "urban myths" are debunked, and I've been reading through the referenced additional material on this topic that does that. I was only further explaining WHY I had mentioned it in the first place. I never said that the fact something is mentioned in some magazine makes it true. That's obviously absurd. My original post contributed something that I had read and didn't know was a myth, and AB7E helpfully provided correction, which I appreciate.
Best wishes,
WA5MZI
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RE: Lightning Protection
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by K5DBX on July 29, 2007
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A couple things you may wish to keep in mind when talking about protecting your shack and antenna systems.
One, in my area, which has a fairly good earth conductivity (30 millimhos per meter) a single rod driven 4'~6' will yield about 160 ohm. Drive that same rod to 8'~10' and it will yield about 60 ohm. Anytime you decide to give lightning a path to discharge, you must also know that one single rod may not be the best decision. Once the initial strike begins, and finds it's way to your single rod system, the ground will begin to saturate to a point where it can no longer absorb any more energy, (this area will be roughly a sphere closly to the distance and legnth of your rod) and the strike will seek another path of least resistance, which more times than not is somthing close to, or attached to that single rod system. This is why you need to provide multiple ground rods all bonded together, to earth in your system so that as this discharge continues after the initial flashover, it will have another route to continue to saturate the earth, and hopefully, not into the shack or power lines. The point is to have multiple rods, spaced further apart than their length, and bonding them all together, preferably in a star pattern.
Secondly, we should always follow NEC requirements, which states that it should also be bonded to the service entrance of the shack/home.
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Lightning Protection
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by K9AMA on July 29, 2007
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ICE ICE ICE That's all you gotta know...ever heard of one of their products failing? Hmmm me neither.
73 Dan
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Lightning Protection
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by WA8MEA on July 29, 2007
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Back to the subject of jars:
Do you suppose older hams had read about Leyden Jars? In particular, Ben Franklin and his experiments with the Leyden Jar? Perhaps older hams confused the use of these jars as a way to suppress lightning? Or for that matter, the use of ANY jar???
http://www.lightningsafety.com/nlsi_info/myths.html
73, Bill - WA8MEA
http://HamRadioFun.com
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RE: Lightning Protection
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by AD5QA on July 29, 2007
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Reminded me of this: http://video.google.com/videoplay?docid=-4889979377809711708
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RE: Lightning Protection
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by W4KVW on July 30, 2007
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Charles(KC8VWM),this system works for "ME" & as the article ask I told what "MY" system or method for my station is!MAYBE "YOU" missed that part of the original posting OM?I will NEVER put a ground on my station since it is NOT needed for safety & in MY OPINION a waste of time!Thanks for your imput anyway!!!Do yours YOUR way & I'll leave mine UNGROUNDED as it has been for 14 plus years }:>)
73's,
Clayton
W4KVW
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RE: Lightning Protection
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by W4LGH on July 31, 2007
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Well...it looks like we've had a pretty good run here, with a lot of great info being exchanged. I was flattered to receive an email from a reader out in the mid-west who asked permission to use my submission in their clubs newletter. I'll be back again with another informative article soon. Right now I am trying to Master my new Yaesu FT-2000, and it got the menus!! So far so good, and the receiver seems to be what they say it is.
73 to all...thanks for all the great posts and info.
de W4LGH - Alan
http://www.w4lgh.com
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by KI6HPO on July 31, 2007
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Hello Alan, W4LGH, et.al.,
I am most grateful for your posting and just as grateful for all of the constructive ideas it has engendered!
However as intriguing and interesting as the responses have been, I was wondering how can someone without a tower [or towers] protect themselves from lightning strikes and atmospheric static discharges?
I've invested quite a bit of money into my 775DSP and would very much like to keep it in the pristine opearting condition which it now occupies. It is hooked up to a 204' "flat-top" G5RV about 20' above ground. A higher elevation is forthcoming.
I have my rig grounded to a single, 10' copper rod via #6 stranded copper wire. The rod is in loamy soil, quite moist and all but 6" is in the ground. The rod is about 15' from the rig.
By the way, someone had mentioned to me, whicle I was digging the hole for the ground rod, that it is a good idea to backfill the ground rod hole wih a combination of rock salt and charcoal. I believe he said that it increses the rod's conductivity to the surrounding soil. True or False?
Currently, I subscribe to the "disconnect and remove" the RG-8 from the rear of the receiver. You are correct; it is cumbersome and not at all convenient.
Since I have no tower, no rebar, no concrete to contend with [just two trees from which my antenna is strung], can you tell me please, what is your best recommendation on how to make my rig [and me!] safe and as resistant to a possible lightning strike as possible?
Many thanks for taking the time to respond!
Alan...KI6HPO
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by K9KJM on July 31, 2007
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KI6HPO:
A ground rod in normal soil should be driven in, NEVER "buried" by digging, UNLESS you have very poor soil and do plan to make an "enhanced" ground by installing the charcoal, Rock salt, And/or other additives.
Whether a tower exists or not really makes no difference for protecting the radio equipment. The same rules of bonding all grounds together, And the "single point" ground where the coax enters the building are important to follow.
IF you "disconnect" the coax, DO ground it somehow. Do NOT just leave the coax lay about! The easy way to do this of course it to have a grounding coax switch at that single point ground. Just switch the antenna to ground.
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RE: Lightning Protection
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by K9KJM on July 31, 2007
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BTW KI6HPO, I would NOT have a ground wire attached to the back of my radio....... IF you insist on disconnecting the coax, Get rid of that ground wire also!
Read the site I provided earlier:
http://members.cox.net/pc-usa/station/ground0.htm
Unless a complete well thought out lightning protection system is installed, Leaving a ground wire attached to a radio is asking for trouble.
Instead, Ground the shield of the coax at several places: Base of antenna, Where the coax enters the building, At the single point ground plate, At least.
Note that several ground rods that are interconnected and bonded to power, etc grounds are required for a decent ground system.
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RE: Lightning Protection
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by W4LGH on August 1, 2007
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To Alan, KI6HPO.... First I would never put salt in or around my ground rod. It may increase the connectivity some, but it is going to eat away at the ground rod faster than one would think. Thus , you are losing ground conectivity.
Best solution I can tell you is to purchase some sort of gas tube discharge device (Polyphaser/ICE/Alpha-Delta) and put it in series with you coax at the ground rod, keeping your ground wire from the device to the rod as short as possible. This will offer some protection for static discharge, and near lightning hits. Not much one can do with a direct hit, but hope that your antenna is completely grounded, and disconnected from your radios.
Hope this helps...73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by KD5PKS on August 1, 2007
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Alan,
Sounds like you have the right ideas. Some here read the tech notes on Polyphaser's site and pronounce it as gospel and the ONLY way to ground something. Your use of solid #2 wire over ground strap is fine. Strap is better but the #2 is effective and more durable. You don't NEED 75' radials to have an effective ground. You don't have to space your ground rods EXACTLY 2x the length apart to be effective. It really depends upon the soil conditions and closer is always acceptable. Coaxial surge arrestors do work to a degree but disconnecting your coax AND throwing it out the window is surely more effective for protecting your rig - a little overkill I think and possibly a fire hazard.
I work in the wireless industry and we take direct strikes all the time. I was inside a structure yesterday when the tower was hit. The #2 solid wire must have worked and the surge never caused any problems inside. This was at a 350' tower with a buried #2 ground ring and associated rods about 10 feet around the base of the tower. We started adding surge protectors to all coax lines about 5 years ago but I have not seen any difference in the amount of damage caused by strikes because we rarely have any equipment damage either with or without them.
My point is that you can have something that is EFFECTIVE without breaking the bank. I guess the tweed jacket with elbow patches wearing grounding professors will try to pick apart my suggestions. I have worked in the field on hundreds of commercial towers for nearly 20 years. I base my opinions on that and can say for certain that what we use is effective.
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RE: Lightning Protection
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by W4LGH on August 1, 2007
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To KD5PKS....
I too, have worked with commercial towers in the broadcast industry and I know what you are talking about. Only difference, with cell towers the antennas are very small (in compairison to HF antennas) and are usually mounted on the sides of the tower, a fair ways from the top. These smaller antennas are less likely to suffer from static discharge than say 135' wire. So I agree that you probably haven't seen much diffence with the discharge devices, as your tower will probably take the brunt of the strike and act as a large lightning rod.
However with HF, I have seen where gas tube discharge devices help a great deal, 1 with static discharge, and near lightning flashes which spiked the antenna. Nothing subsitutes from a good ground system, and there are many deffinations for a good ground system. However I still strongly suggest that everyone with any amount of wire in the air use these devices to add that extra protection. Again, they DO NOT subsitute for the best ground system you can install.
73 and good luck! de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by KC0NYK on August 1, 2007
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I do take the hour or so every six months to hook up my 5kv megger to the grounding system and if there happens to be an improper reading, do something about it. A little pm goes a very long way! You are correct about the braid; however I wanted to accomodate the movement in the crank up tower more effectively. As in all engineering, there are tradeoffs to be considered.
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Lightning Protection
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by K0IC on August 1, 2007
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As a former broadcaster I know from experience it is almost impossible to over-engineer the grounding. The electrical service entrance box is a common point where multiple grounds are tied together on the buss bar. I use a couple of old water pipes, a ten-foot ground rod in the dug out sump pump hole, and bond to both the telephone and electrical grounds. I have MOVs all over the house but do not have an all house MOV yet as the owner would have to hire to have that done. I have not had a problem as long as I have done this. I watch TV and listen to radio in horrible lightning storms with no ill-effects! In contrast our local telephone company has had major damage twice when they get "smart" (unprofessional) with their grounding.
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RE: Lightning Protection
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by W4LGH on August 2, 2007
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The only problem with using MOV's is that they need to be in a metal box, as they can and will catch on fire with a large surge. Have seen them do that many times over the years, so don't just put them in your plastic wall boxes!! I had thought of doing that until I saw one burn. The same applies to those plastic power strips as well. The best place to put them would be in your panel box across the breakers.
No need is swapping the devil for the witch!
73 de W4LGH - Alan
http://www.w4lgh.com
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Lightning Protection
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by N4ATS on August 4, 2007
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Being an RF Engineer for 25 years, and seeing the damage lightning caused to a "superior grounded shack" , reconsider.
If you can not achieve a ground potential BELOW the line ground in your home, you are wasting time. A differential of only .5 ohms at 35E+6 volts is pure destruction. The so called “ground bars” everywhere do nothing but “drag in” the lightning. After several years of study at Sandia Labs, the ONLY way to save your equipment from a lightning storm is to simply get rid of ALL grounds except the rod near the tower. NEVER “strap radios and amps together” with braid or anything, unplug the radio from the wall and stick the coax in a glass just to keep a flame at the tip IF it hits direct. Grounding is extremely dangerous.
Usually whatever is tied to a “bar” will be damaged in the event of a direct hit.
I have been hit 5 times in 10 years , never lost anything , I have friends that have the so called “bars” everywhere and do nothing except the write the claim to the insurance company after the hit.
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RE: Lightning Protection
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by KI6HPO on August 4, 2007
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Hello Bill,
I've invested quite a bit of money into my 775DSP and would very much like to keep it in the pristine opearting condition which it now occupies. It is hooked up to a 204' "flat-top" G5RV about 20' above ground. A higher elevation is forthcoming.
I have my rig grounded to a single, 10' copper rod via #6 stranded copper wire. The rod is in loamy soil, quite moist and all but 6" is in the ground. The rod is about 15' from the rig.
Should I just disconnect the #6 ground wire and discard it, never to use it again?
Is this singular menthod of supressing atmospheric static discharge and a lightning strike as easy as disconnecting the electrical plug from the outlet and removing the coax from the rear of the rig and placing the end of it in a glass bottle?!
Alan...KI6HPO
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RE: Lightning Protection
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by W4LGH on August 4, 2007
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Geez...all that money spent on HALO systems, and exotic ground systems, and all the commercial stations had to do was unplug from 3 phase 440V ac line and put the 4" coax in a LARGE GLASS bottle?
Hmmmmm...boy are there gonna be a lot of PO'ed station owners if they find this out!!
I seriously don't know what kind of broadcast engineer you are, but I can assure you, I would never hire you to do any work for me!!
There is NO sure cure for lightning protection, but not grounding anything and putting your coax in a glass jar probably doesn't make the top 1000 of suggestions! If you think about it, the heat alone on the tip of your coax connector would shatter the glass.
Good luck!
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by K9KJM on August 4, 2007
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Well, I sure hope NO ONE listens to "RF Engineer" N4ATS WRONG HEADED advice!!!!!
Of all the wrong things to do, Disconnecting coax and putting it in a glass jar ranks at the top of the stupid things to do! IF anyone insists on "disconnecting" coax (A very dangerous practice in itself) The thing to do with the coax is to somehow put them to ground. Simply using a coax switch is the easy way to do that.
To leave unconnected coax lay about, Even in a "glass jar" if that station takes a direct lightning strike, Would be like having dynamite in your room!
The foolish glass jar stunt helps for simple static build up only.
Commercial repeater towers, Cellphone site towers, Broadcast towers, Police, Fire, And my own towers here on the hill take direct lightning strikes most every storm, With NO DAMAGE to equipment.
Had N4ATS bothered to read ANY of the links provided, He would have learned that proper BONDING of grounds is what prevents damage, NOT the quality of the actual "ground" itself.
I will however agree that some of the steps taken by some hams of running "braid" or whatever between devices is also the wrong thing to do.
For MANY years now, It has been known that the "Single Point" ground (Near where lines enter the building) Is the ONLY place to "ground equipment.
Grounding things the Right way prevents damage.
The "buss bars" behind equipment went out in the 1950's as being the wrong way to ground.
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RE: Lightning Protection
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by N4ATS on August 5, 2007
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Guys , there is a difference in a commercial station. They are ALWAYS on line. The typical Amateur Radio Station I am talking about is the guy like you who turns off the equipment in a storm , you know you do! There is a big difference. The glass jar ONLY stops a flame (if any) from starting a fire. I know for a fact , that in most cases having all your equipment tied to a bar that is above the line ground (ohms) potential smalls disaster. Commercial station HAVE to ground because they are on 24/7. Get the facts straight...
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RE: Lightning Protection
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by N4ATS on August 5, 2007
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P.S. KI6HPO , Yes , the ONLY real way to protect your radio from lightning is to unhook it from ANY electrical connections when not in use which eliminate potentials. You see my shack picture on QRZ? I have NEVER had grounds hooked up and have been hit 5 times in about 10 years DIRECT. My tower ground is a 10 foot rod saturated with salt. That’s it. My neighbor has the "bar" grounds all over , when he gets hit he replaces the dryer , radios , computers , and everything else hooked to them.
I live in Florida , lightning capital of the world , I would NEVER "tie" my radios to any possible means of electrical connections that can enable lightning to track it.
Ask yourself this , when a storm comes , why do you unplug the TV or Microwave? Because if the equipment is"isolated" from any electrical path , you will NOT have damage in the event you get a direct hit.
So the question is "why" do you want to give the radio a possible path for lightning to follow?
A.E.S. in Orlando has a million dollars in radios right smack under a pile of antennas the we put up. Would you rather buy one that was "so called" protected via a ground bar to the outside world or buy one that has never been attached to the outside world thus never seen lightning?
C-Mos and gAsfets only take a small amount of current to make "flakey". With a simple path of 1/2 ohm at 35 million volts is what???? (you can gat ohms law calculators on the web).
The bottom line. Unhook your equipment when not in use , place the coax in some type container that will stop any static or whatever from burning the carpet and you will survive the worst of the worst. Grant it , your antenna make take the beating , BUT your equipment will not.
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RE: Lightning Protection
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by N4ATS on August 5, 2007
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One last thing for K9KJM , My jar never blew up? whats up with that?
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Lightning Protection
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by KN4LF on August 5, 2007
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KB5F Said:
.....A third concept to survival that I have not seen much in the thread is dissipation of the charge to begin with. It all goes back to Franklin and his lightning rod. On the one hand, we put a high pointed rod to snag the strike, 40 degree cone of protection, etc. On the other, behold, St. Elmo's fire indicating DISSIPATION of the negative cloud charge and the equal and opposite positive ground charge.
Several firms give written guarantees of no strikes to protected equipment. Essentially a high umbrella with spikes pointed skyward, the guarantees are
real. And expensive. I installed a porcupine looking bound stainless steel bundle of 25-50 sharpened 12" SS spikes at the top of the mast, cost was about $50.....
KN4LF Says:
The bottle brush/porcupine/spline ball air terminals and ESD's don't work as advertised. It's a total fraud.
Check out my website at http://www.kn4lf.com/kn4lf60.htm.
73,
Thomas Giella, KN4LF
www.kn4lf.com
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RE: Lightning Protection
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by K9KJM on August 5, 2007
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N4ATS: Your jar never blew up?? YOU NEVER took a direct hit on that coax! Simple! You are living in a fools paradise!
I Keep ALL my radios online ALL the time. I NEVER "disconnect" anything. AND my towers have taken many direct lightning strikes over the years, With NO damage to any of my equipment.
So too do the towers I work on, Sheriff department, 500 foot commercial tower that has our ham repeater antenna at the very TOP, (And others), Takes Direct lightning strikes most every storm. etc etc etc.
We monitor some of these towers with Polyphaser LSC series lightning strike counters to know exactly WHEN they do take real direct strikes. Do you?
YOUR wrongheaded advice takes hams back 50 or so years in protection history. Sad, Very sad.
Please study up to date information on how things are done nowadays before giving out the bad advice.
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RE: Lightning Protection
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by N4ATS on August 6, 2007
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I find it very hard to imagine you took direct hits, with everything turned "on". If you took a direct hit on your antenna with everything "on”, there would not be anything left, especially at home. Commercial sites are different in they spend tons of money on lightning; however the typical user like yourself would never spend that kind of cash. I do not understand why some are arguing here about something so simple, If your equipment is OFF line and not hooked up to any electrical connections, The cahnces of survival are very high. What part of this do you NOT understand?
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RE: Lightning Protection
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by W4LGH on August 6, 2007
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I guess some people will have to learn the hard way!
Most of what people think are "direct hits" really aren't, but very very close by. There is a major display of evidence from a direct hit. If you have never seen lightning directly hit a tree, you have missed a very spectular site, to see nature turn that much power lose at one time. Direct hits to commercial building, towers and such rarely have any damage because of their "GROUNDING SYSTEMS", allowing the energy to be evenly distributed back into the earth.
Even ole Ben Franklin was smart enough to have a ground rod hooked to his kite!
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by N4ATS on August 6, 2007
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I agree , however people keep missing the point here. We are talking about the "typical ham radio user" and when his equipment, NOT THE TOWER , is NOT in use to remove any connection to the outside world eliminating the possibility of the radio getting damaged , why is it so hard for one to see this?
Of course if you plan on keeping the radio "ON" you must have a darn good ground, however we are not talking about that. You must be brave to do that anyways or have money to burn.
If you do not have means of measuring ground, in reference to real ground and have excess ohms in the ground system , you are wide open for destruction.
Again , people here say to leave the ground hooked to the radio when not in use. My question is why?
I HAVE been hit direct several times , you know when its real. It took out my well and pump several times however my equipment WAS unplugged from ANY wires and I never had ANY claims.
My neighbor has the elaborate grounding bars , he was hit , lost everything. He now does what I do now , the smart thing. UNHOOK IT WHEN NOT IN USE!
Please read what we are talking about here...
1) THE TYPICAL HAM RADIO USER , not commercial
2) The user that turns OFF is equipment in a storm
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RE: Lightning Protection
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by K9KJM on August 6, 2007
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Yep, My towers take DIRECT lightning strikes while I am operating. SO do ALL repeater towers, Police, Cellphone towers and on and on.
(As shown by my Polyphaser LSC series lightning strike counters)
YOU seem to be missing the points. A modern day properly installed system is grounded at the "Single Point Ground" where the coax and other lines enters the building ONLY.
There are NO little braid ground wires to the back of any of my equipment. That line of thinking went out in the 1950's or so.
In fact, The cable television "Head end" tower sites I built back in the 1980's had commercial tile flooring (To help insulate) And the equipment racks were all built up on 2X6's to further insulate them from any "sneak" ground paths.
We ran close to 100 channels on those cable systems, Which means well over 200 pieces of equipment. (Satellite receivers, Modulators, Videociphers, etc)
And NEVER had any damage to any of that equipment either. Many (And some very large) direct lightning strikes hit those towers. (Witnessed and proven with the counter)
See this good site on proper lightning protection, Among others: http://members.cox.net/pc-usa/station/ground0.htm
And yes, He mentions "Disconnecting" equipment. Please read the ENTIRE site, Along with the links he provides for a good overview.
The Polyphaser site is a particular good one.
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RE: Lightning Protection
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by K9KJM on August 6, 2007
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IF anyone has a well pump taken out by lightning that is a sure sign of things at that location NOT being properly bonded!
One of my towers is located less than 6 feet from my well case (That tower took direct lightning strikes years ago before I installed much taller towers)
These towers are ALL bonded together, AND bonded to the well case (A very good lightning protection ground)
To have a well pump damaged means that the AC supply at that location is very poorly protected, AND the AC entrance panel ground is NOT bonded to the well case like it should be.
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RE: Lightning Protection
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by KI4FNC on August 6, 2007
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K9KJM: I am having a hard time grasping your statement about the grounding terminals on the back of amateur equipment? Why are they put there in the first place then? I was taught in many books to have a 'star configuration' pattern to a common ground. I thought the 'old school' way of thinking was to interconnect your equipment with each other and then to a common ground. I would say that disconnecting your coax completely from the back of your rig is a good idea,... maybe a hassle for some though. Where would be the proper place to put the coax end?,...N4ATS suggests a glass jar which is an insulator. I guess the strike could arc outside the glass jar, but it seems feasible to put the coax somewhere?
I am learning so this thread has been a good read. I appreciate the wisdom that is being imparted!
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RE: Lightning Protection
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by K9KJM on August 6, 2007
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The little wing nuts on the back of radios I expect are still a holdover from the "Old" way of grounding,
And if I were a manufacturer, I would sure put in place plenty of "safety" things to help prevent lawsuits. (If you do not have a proper Single Point Ground system, You would still have some where to install a DC safety ground. Note I say "DC safety" ground. Not to be confused with a proper lightning ground)
Actually connecting grounds to the wing nuts on radios can add ground loop problems, To say nothing of giving lightning a nice path right THROUGH your radio to ground!
A much better way is to do it the right way with the single point ground system.
Not only is disconnecting coax foolhardy, When a storm is approaching it is very dangerous to personal safety! The glass jar stunt??? Think it over. Lightning that has just traveled several MILES through the air will have no trouble exploding that glass jar and setting your house on fire!
A much safer way it to simply install a good quality coax switch that puts all antennas to ground when not actually being used. (With the switch well grounded right at your single point ground)
Lacking the coax switch, The proper way to deal with disconnected coax would be to screw them to a grounded SO-239 connector, Again, at your single point ground plate.
The "star" grounding configuration, Big buss bars behind equipment, etc was popular in the 1940's and 50's BEFORE it was discovered how to really prevent damage to radio equipment with the single point ground system.
Check out a modern day communications tower site.
The building located right next to a 500 or so foot tower that WILL take direct lightning strikes most every storm:
All coax lines enter the building at a "single Point" ground plate. That copper plate is grounded to the actual ground system with a number of flat copper straps. (Usually four 6 inch wide straps) That same copper panel is where ALL lightning arrestors, Polyphasers or whatever brand is used are located.
You will find NO copper "braid" or other grounding conductors attached to the actual radios themselves.
(At least not in the installations that do not suffer lightning damage anyhow)
Here is another good site: http://www.comm-omni.com/polyprod2.htm
Scroll down to the actual articles on properly installing lightning protection for radio systems.
Polyphaser is one of the better companies that supply equipment for many public safety tower sites.
I.C.E. (Industrial Communications Engineers) is another good one that sells good equipment for lower prices.
(Actual lightning arrestors are not nearly as important as having ALL your ground systems properly bonded together, So when you do take a direct strike, There are no huge voltage differences between things.)
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RE: Lightning Protection
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by K9KJM on August 6, 2007
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Here is a fairly lengthy article right here on Eham written by WB2WIK.
http://www.eham.net/articles/8951
Expaining how usless those little wing nuts on the back of radios really are.
While Steve lives in a very low lightning area and does not really deal with modern day proper lightning protection systems, He sure does punch a few holes in lots of ham radio "old wives" tales about grounding!
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RE: Lightning Protection
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by W4LGH on August 7, 2007
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The ground lug on the back of your radio is NOT for lightning ground, but for RF & power grounding. It is very important to have all your equipment binded together. The same reason all of your electrical sockets are all grounded and bonded to the main house power ground. A simple read of the NEC (National Electrical Code) will explain why this is necessary.
Lightning grounding takes place OUTSIDE of the shack, with the idea of keeping the lightning away from and out of your shack.
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by KD5PKS on August 7, 2007
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I am of the school that believes in grounding everything to the single point ground including radios. The commercial radios I work with are rack mounted and not individually grounded but each rack is with a separate run to the ground bus bar. The racks are insulated from the floor with plastic sheets. We also use a halo grounding system but only significant pieces of metal such as conduit and door frames are attached to the halo.
The ground bus bar is typically around 24 inches wide and divided into 3 sections. The first section on the left is where connections are made to potential providers of surges such as coaxial protectors and Bias-T's. The middle section is where the main absorber is connected. The absorber is the direct connection to the outside buried ground ring. The right side of the bus bar is where connections to protected equipment are connected. That would be the ground runs to transceivers for instance.
The plan is to present a direct path to ground via the absorber. The radios and racks are not grounded or connected via any other point so if a surge enters from antennas, power source, etc, the most direct and lowest resistance to ground is through the absorber and not across the bus bar and through the equipment which is otherwise insulated with no direct path to ground except through the bus bar and absorber. This has been a very successful system for us. You can't eliminate the possibility of lightning striking but you can do a lot to control the surge.
Completely disconnecting your station may very well be pretty effective but not very practical for a typical ham who may have an HF rig or two, VHF rig or two, packet rig, computer with internet and rig control cables, etc. That's a lot of jars using N4ATS' method. N4ATS also suggests that since his neighbor uses ground bus bars everywhere and still has lightning damage. I'd say that his neighbor isn't likely to be following the single point ground method if he has several "bars everywhere".
The suggestions of operating while taking direct strikes sounds a little far fetched to me. I have seen direct antenna hits and they almost always result in a damaged antenna. The types of antennas I deal with are typically wire inside of fiberglass tubes and will often look like an upside down broom after taking a direct hit. On the other hand, our towers get struck all the time with no problems. I think this is what some mean by 'direct hits'.
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RE: Lightning Protection
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by N4ATS on August 8, 2007
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Finally...
Yes it is a pain to unhook stuff, however, I am the type person that wants my equipment to always work after severe storms and bank on it , the storms here in Florida are usually pretty bad.
As for “many jars” , not for me , I have two coax’s that I unhook , they go in ONE jar. The LAN and Power Cords (about 4 or 5) just hang unplugged.
It takes me about 30 seconds to unhook everything. This with respect to the $8 or $9 K in radios and gear I own is near to no effort.
I have an electronic lab as well (http://n4ats.com) in which all power is on one A.C. strip. I unplug it, done.
There is no safer way to protect “HAM RADIO GEAR” (not commercial stations) simply unhook it from any electrical paths when not in use. It has been working for me for many years as well as others I know.
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RE: Lightning Protection
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by W4LGH on August 8, 2007
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Well I just received and install my "whole house" lightning power protection. This unit is made by E-Clips and is supposed to be one of the best on the market. It mounts in your main Breaker box and protects against power surges thru out your entire house. See specs listed below. Or you can visit their website.. http://www.eclipspts.com
Every little bit of protection has to help and certainly can't hurt. This unit has the best specs that I have seen on a device of this type.
==================================================
Panel Protector / Hardwire / 240 MBAA 2nd Edition
Specifications – Operating:
Maximum Operating Voltage:
240 V AC, Single Phase 50/60 Hz
Typical Leakage Current:
<5µ amps
Operation Temperature:
- 40 to +85°C
Connectors:
Hardwired
Lines Protected:
L1-L2, L1-N, L-2-N
Installation Configuration:
Parallel
Specifications – Electronic:
Maximum Surge Current (8x20µs):
80,000 Amps Total
Maximum Surge Voltage (1.2x50µs):
10,000 Volts
Capacitance:
<2,000 pf
Clamping Voltage:
250 Volts RMS
Clamping Response Time:
<5 nanoseconds
Current:
Non-Load Bearing
Voltage:
Voltage Sensitive
Design:
Thermally Fused Hybrid
Operation Indicators:
2 Light Emitting Diode (LED) (Phase Protection)
Audio Alarm (Thermally Protected)
Power Dissipation (8x20µs):
10,150,000 Volts Amps
Energy Dissipation:
1000 Joules
UL 1449:
1449 Second Edition
UL Recognized Component:
File E121637
Meter Box or Main Panel USL and CNL Approved:
United States / Canada
Dimension:
Depth 1 3/8”
Width 4 ˝”
Length 3 3/8
Weight: Approximately <1lb.
Pass Voltage Tested to ANSI/IEEE B3 Impulse:
330 V Peak Rating - UL’s Best!
UL 400 Rating (L/N)
E-Clips surge suppressors have a Lifetime Product Warranty.
73 de W4LGH - Alan
http://www.w4lgh.com
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Lightning Protection
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by K4TAX on August 8, 2007
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A single ground rod does a ground system or lightning protection system make.
Three Points;
(A) Any and all grounds served by a common electrical service must, *repeat*, must be bonded together, preferably outside the structure. Failure to do this will cause a step voltage to exist between 2 or more grounds and likely your radio, although antennas disconnected but connected to ground and the AC mains will emitt smoke.
(B) Provide some means to bleed off static build-up on the antenna system. You pick the device, just pick and use one
(C) A whole house surge protector installed at the main breaker panel is a good investment.
With today's antennas and radios, RF ground is typically not necessary. Coax fed and balanced fed antennas do not need a station ground for proper or efficient operation. If your station uses a coax fed antenna or balanced fed antenna and requires a ground, then there is something wrong with your antenna. Vertical antennas and end fed Zeps or inverted L's do require a ground system outside and under the antenna for proper and efficient operation.
Use the 3rd pin AC ground for safety purposes and keep the lightning protection system outside of the house and away from the radios. Solves the station ground loop problem too.
73 Bob, K4TAX
RMcGraw@Blomand.net
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RE: Lightning Protection
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by K5DBX on August 9, 2007
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W4LGH - Alan, Our electric company provides for a small monthly charge a device mounted under the meter that is used as a whole house surge protection with a pretty healthy insurance policy to boot...
As another great Oklahoman used to say, "It's not what a man doesn't know that scares me, but what a man thinks he knows that is just plain wrong that scares me.." (Will Rogers)
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RE: Lightning Protection
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by W4LGH on August 9, 2007
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K5DBX said..."W4LGH - Alan, Our electric company provides for a small monthly charge a device mounted under the meter that is used as a whole house surge protection with a pretty healthy insurance policy to boot..."
Yes, Florida Power & Lights offer the same thing @ $9.95 per month, or an extra $120 a year. I thought about it and decided to purchase my own for less than one years rental. The unit has a lifetime warranty, and will be replaced if distroyed, and I keep a seperate insurance rider on my equipment. I have a local electrician friend that has used these units in many locations and says it has worked great in some super troubled areas, so I figured we'd see. Of course the best test is to never have it tested! I figureds it couldn't hurt to have a little extra protection, plus it protect other things in the house as well.
73 de W4LGH Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by KD5PKS on August 9, 2007
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Quote N4ATS
"As for “many jars” , not for me , I have two coax’s that I unhook , they go in ONE jar. The LAN and Power Cords (about 4 or 5) just hang unplugged."
It takes me about 30 seconds to unhook everything. This with respect to the $8 or $9 K in radios and gear I own is near to no effort."
My jar comment was rhetorical and intended only to make a point that most hams have several antennas that will need to jarred up. It may take YOU 30 seconds to disconnect YOUR station but that may not be the case with many others. The problem is that if any of your antennas take a direct hit, that energy WILL go somewhere and it's routed to your shack with no path to ground and will likely arc to something which could start a fire. Lightning WILL find a path to ground and it won't just vaporize inside your jar.
"There is no safer way to protect “HAM RADIO GEAR” (not commercial stations) simply unhook it from any electrical paths when not in use. It has been working for me for many years as well as others I know."
I agree if you disconnect entirely. It's sort of like abstinence, it works every time. I have a Telpac gateway packet station that I leave on even when I'm not present. I live n south Louisiana and there is a thunderstorm potential everyday as is where you live. I would have to disconnect it every morning and reconnect in the evening to avoid the possibility of a hit. Point is, some HAM RADIO GEAR is on most of the time and requires some effective grounding. What is done commercially can be just as effective on ham stations and that is whole point. Your idea of putting cables inside jars goes against everything in use commercially at least what I've seen and is an invitation to disaster.
I think you really mean there is no practical way to ground a typical ham radio station such as a commercial installation is. I agree and often argue here that some things are overkill with respect to practicality and cost. You can have a ground system that is effective without breaking the bank.
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RE: Lightning Protection
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by N4ATS on August 9, 2007
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I agree, somehow though this topic "How do you try to protect yourself and your shack equipment from lightning" turned in to a major argument because some of the good 'ole boys above started injecting commercial status into these threads.
I started out by being very clear for the “typical user that does not use his equipment all the time” and ended up here…
I also made it clear, a glass jar ONLY stops static or flame from hitting a carpet or whatever. Somehow this idea got elevated to me saying it will withstand a nuclear explosion.
I have been using the same “jar” for many, many years and it never blew up or anything. It has a few pelt marks on it but that’s it.
By the time the lightning travels through the coax after the DC Ground at the antenna dissipates most of the charge through the tower ground, it is nothing more than a fairly large spark at the coax end. As a matter of fact, I actually saw it one time while sitting in the room. I heard a crack, seen and heard a pop behind the TV, looked at the jar and seen a small spark.
My point is and always was, when not in use, unhook it for a guaranteed result that the equipment will work when hooked back up, but it seems that some people thing that’s wrong. Who in there right mind would think you are better off hooked to the outside world when not in use???? Again “not in use”
It is one thing to ground a system using bars and a single point knowing it is below the reference ground (outside line on the poles) , and another to ground a system and have resistance. You and I know, it does not matter how many bars or grounds you have, it’s the resistance that will hurt because of the alternate ground path that “MAY” take place through the chassis of the units attached to it.
I have seen several stations, totally blown up with welt marks all over the place because of ground bars. I repair radios (http://n4ats.com) , been doing it for 24 years as a hobby, and have had MANY radios come in with the same story “They were grounded good” . Some of these people were NOT using there radios, and probably have not in months. They thought they were safe with them hooked to the outside world. (grounded) when in turn , if they were unhooked while not in use , they would have survived.
If one has the money to burn and has to have his radio turned on in the midst of a storm, that’s OK but I know for a fact if it takes a direct hit on the antenna near the feed point, no matter what kind of ground it has, the radio is at least going to blow out the front end.
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Lightning Protection
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by K8ZES on August 9, 2007
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Living at 2100 ft elevation above sea level (decent for this area)for the past 25 yrs, I had constant problems with lightning to the tune of hundreds of dollars a year for blown electronic gear. The house and barn (50 ft from the house) are 1855 vintage with the old and properly connected old time lightning rods. The barn's steel roof was grounded as well as all the three towers (90, 60 and 60 ft resp.)After never seeing a close "hit" I finally figured out the problem was surge voltage caused by lightning induced voltage into the long relatively unprotected rural power lines. After several months of argument with power company engineers and demanding they install line surge protection (which they were willing to sell me but I said it was their resposibility, not mine), they measured all my ground points (less than 15 ohms all around)and connected two expensive line monitors, one at the house and at the barn. Each week they'd come back and take out the history and go back. Finally one day we had a huge surge which blew one monitor to pieces and seriously damaged the other. A week later they installed a Cooper Industry "Storm Trapper" HSE right in series with the power meter (free). That was some three years ago and life has been good. Strangely enought this device is built 20 miles away in Olean, NY!
My 50, 222 and 144 yagis do have Alpha Delta coax line protection but nothing else does.
I usually leave everything connected.
Sid Emmons, K8ZES/2 FN02
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RE: Lightning Protection
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by K9KJM on August 9, 2007
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QUOTE N4ATS: "If one has the money to burn and has to have his radio turned on in the midst of a storm, that’s OK but I know for a fact if it takes a direct hit on the antenna near the feed point, no matter what kind of ground it has, the radio is at least going to blow out the front end."
That statement is flat out B.S.!!!!!!
Do you really think the cellphone tower site owners rush out and "disconnect" before every storm? OR the repeater sites? OR broadcast stations? Or police and fire radio tower sites? OF COURSE NOT! AND they do NOT have the "Front end blown out" of the radios that are directly connected to the antennas on the tower that just took a direct lightning strike!
My own station (Along with many others) have been taking DIRECT lightning strikes for over 30 years now with NO DAMAGE.
How hard is that to comprehend???
Too bad some hams are so very narrow minded and still in the 1950's that they cannot learn the right way to do things.
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RE: Lightning Protection
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by N4ATS on August 10, 2007
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You have got to be kidding... Here we go again with the commercial stuff. I quit... Some of you need to stick with the point and READ before you post...
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RE: Lightning Protection
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by W4LGH on August 10, 2007
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N4ATS said..."You have got to be kidding... Here we go again with the commercial stuff. I quit... Some of you need to stick with the point and READ before you post..."
I think the example of using commercial installations is to SHOW that there are OTHER ways of doing things. No one has said that completely disconnecting everything isn't a good way to protect yourself, but in most cases with ham radio it is impractical . As most of us have way to much to disconnect. Also that it would be better to put your coax to ground, than put it in a glass jar! Check out the photos of my shack, do you want to try and disconnect everything there , evertime you knew a storm was coming? By the time I finished disconnecting the storm would be over!
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by K9KJM on August 11, 2007
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Quote: "RE: Lightning Protection Reply
by W4LGH on August 10, 2007 Mail this to a friend!
I think the example of using commercial installations is to SHOW that there are OTHER ways of doing things. No one has said that completely disconnecting everything isn't a good way to protect yourself, but in most cases with ham radio it is impractical . As most of us have way to much to disconnect. Also that it would be better to put your coax to ground, than put it in a glass jar! Check out the photos of my shack, do you want to try and disconnect everything there , evertime you knew a storm was coming? By the time I finished disconnecting the storm would be over!
73 de W4LGH - Alan
http://www.w4lgh.com"
EXACTLY! I could not have said it better myself!
Not only is it very impractical (And dangerous) to "disconnect" the various coax runs, Rotor wires, Closed circuit camera coax, etc etc. I WANT some of my radios on the air DURING a storm for Skywarn spotting!
To scurry about fretfully "disconnecting" coax as a storm approaches is not my idea of having an emergency communications system, Able to "help out" when disasters strike.
(Anoter ham in town here recently found out just how dangerous "disconnecting" equipment is. Even though he had all of his coax runs totally disconnected from all radios, Lightning came in the "back way" via the AC power line and almost started a fire, Going to ground THROUGH his radios! Destroying several of them!)
Meanwhile, During the SAME storm, My second tallest tower (120 foot Rohn 35G) took a very large direct strike, And again, Caused NO damage to equipment here.
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RE: Lightning Protection
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by W4LGH on August 11, 2007
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Quote.."Lightning came in the "back way" via the AC power line and almost started a fire, Going to ground THROUGH his radios! Destroying several of them!)"
This is why I just purchased and installed the E-Clips whole house surge protector! This unit installs directly in your breaker panel, right across your mains. After doing much research, I found this brand and model to have the best specs. The one spec that is the MOST important is the clamping voltage! Most systems don't clamp until 300 to 500volts, thats still enough to cause damange. The E-Clips clamps @ 250Volts with is 125v per side!
So I am trying to cover both my front and back doors, as best I can! An extra couple hundred bucks in protection is a lot cheaper than replacing a $3000 radio!
73 de W4LGH - Alan
http://www.w4lgh.com
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RE: Lightning Protection
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by WA5MZI on August 11, 2007
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K9KJM said: "For MANY years now, It has been known that the "Single Point" ground (Near where lines enter the building) Is the ONLY place to "ground equipment.
Grounding things the Right way prevents damage.
The "buss bars" behind equipment went out in the 1950's as being the wrong way to ground."
I'm confused about the role of the bus bar and would appreciate some clarification. The latest editions (2007) of the ARRL Handbook and the ARRL Antenna Book both feature an illustration showing a table with four pieces of ham equipment, each of which is connected via braid to a 1/2" copper pipe that runs along the back of the table. This pipe is in turn connected by a "low-impedance conductor, as short as possible" to a ground rod outside the structure which is also bonded to the electrical service entrance panel. I would understand this as being a single-point ground, since it's all bonded together. I'm confused about what alternate method you are recommending. Are you saying that each piece of ham equipment must have its own separate ground connection to the electrical service entrance panel and its ground? What's wrong with bonding them all to a bus (the copper pipe, in this illustration) and bonding it to the common ground that everything else is bonded to?
Thanks for your help.
Steve Westfall
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RE: Lightning Protection
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by W4LGH on August 11, 2007
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There is nothing wrong with bonding everything to a single point. I just had my ground system tested with an earth ground meter. Boy was I surprised! The NEC says your house ground should be under 25 ohms, and most around here achieve a 4 to 10 ohm value. My house ground tested in @ .5 ohms. We then tested my antenna ground system, and it tested in @ .6 ohms. When bonding the 2 together, the total can out to .5 ohms. This is about as good as it can get! Remember electricity & lightning are seeking the path of LEAST resistance.
73 de W4LGH - Alan
http://www.w4lgh.com
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