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[Articles Home]  [Add Article]  

Lightning and Grounding

Michael S. Higgins (K6AER) on March 30, 2006
View comments about this article!


Well it is that time of the year when postings turn to grounding and lighting protection.

So much information has been posted on lightning protection in this fourm you could spend hours going through all the information listed and I would recommend doing so. Use the search engine in eHam and by all means forget the naysayers of grounding. Go to the PolyPhaser site and read their tutorials on lightning protection. Go to Lyncole, Hagar and ICE (Industrial Communications Engineers) and read their tutorials on grounding. There is no short cut to lighting protection. Your whole station and home needs to be addressed as a complete solution. Now if you live in the Northwest you can skip the rest of this article for your chances are very slim you would even see a thunderstorm. For the rest of the county this is an aspect of the hobby we have to deal with. This article is a reader's digest version of what must be done for surge protection and I hope it start you thinking about your home and station.

Every other year on average my station gets hit by lightning. This was not a problem when I lived in LA; I had a greater chance of being hit by stray bullets. I live in a very high lightning prone area called the Palmer divide in Colorado. June through August we have thunder storms every day with up to 40,000 strikes a day on average during those months. I am on my 3rd GP-9 antenna at the top of the tower. When a storm has gone by and I find what's left of a GP-9 in toasted shards all over the ranch, it doesn't take a rocket scientist to know what happened. I have lost no base station equipment to a lightning strikes but I have spent considerable time putting in proper grounding and surge protection on my station. As for the tower top fiberglass omni sticks, they're sacrificial and that just the cost of doing business where I live.

Proper grounding and surge protection works and works very well. The key is setting up low resistance grounding and the proper installation of grounding material. Disconnecting you equipment and putting it into a Faraday Shield box will work well but if you live in an area like my QTH you would be off the air for 3-4 months every year. Some hams like my self have more than one radio and going this route would mean my hobby is station assembly. I can't speak for most hams but after doing that a few times it looses its novelty.

The cell phone industry looses less then 20 sites a year to lightning. There are approximately 500,000 sites between Verizon, Nextel, Cingular, Sprint and others. Generally it is because the DSL line is struck and not the radio equipment. In the cell phone industry we ground at the top of the tower, base of the tower and where the cable goes into the facility. The facility has a ground halo inside and the all equipment is grounded to NEC code. Surge protectors are connected for all incoming and outgoing lines at the ground demarcation point. Site ground resistance is generally below 3 ohms. Four 20 foot deep ground rods is a grounding minimum. The AC entry panel has surge protectors (95% of all lightning damage comes in through the AC panel) and most importantly all the facility grounding is bonded together.

Power lines take by far the greatest hits and the pole flash-over-rods pass any surges below 10,000 volts. That still leaves a lot voltage coming down the power line. The primary and secondary portion of the pole transformer can arc over and your home is next in line. Your home AC panel should have a surge protectors connected to the panel. You worry about your ham equipment but what about your expensive entertainment and appliances not to mention the possibility of fire. You can protect your home and panel for under $100. Intermatic makes the Panel Gard model number IG1240RC surge protector for $60 not including the two additional circuit breakers. This unit has LED's to indicate the units status and wither you have taken a power surge. Installation is just three wires into the panel.

Did I mention lightning rods for the roof? Lightning is fickle and might miss your gorgeous tower and strike through the roof to the electrical wiring in the ceiling. The ground return in your home wiring connects to the master ground in your AC panel. Remember a lighting discharge is looking for the lowest impedance path to ground, i.e. earth. If your live in a highly lightning prone areas like Colorado, Florida and much of the mid west, lighting rods are a good investment. National Lightning Protection in Denver makes all the necessary material to install your lightning rod system. Their web site is a wealth of information.

In my own station, all grounding is bonded with a number 0 solid copper bonding wire. My ground resistance is less than 3 ohms. I have several deep (20ft. by 2 inch) ground rods for the tower, AC panel and shack location. I also have a surface ground field of 21 8ft. ground rods spaced 16 feet apart, spread out in radials from the tower. At the base of the tower is a lightning/surge protection panel for the coax, rotor cables and stepper motors on the beam. For the surge protection box I use 2 inch wide copper strap. Copper strap has much lower impedance than copper wire and much of lightning's energy is in the RF spectrum.

Coaxes are grounded at the top of the tower as well as the base. The AC panel has a commercial lightning protection panel to take care of incoming AC surges. The whole station is run on a pair of 3000 watt APC UPS systems to isolate the AC main from the equipment for minor surges. At the station, coaxes are terminated at a pair of grounded Alpha Delta coax switches and during storms the coax switches are in the grounded COM position. All equipment is grounded to a master ground buss bar on the back of the operating station. The master AC feed to the station has a commercial disconnect in the shack. I know many of you will this is excessive but proof is in the pudding. I have suffered no equipment losses due to lightning strikes.

Remember if the cell phone, radio, public service and computer industry disconnected equipment for every summer storm, you would not have communications coverage or internet service for five months every year. The communication industry is connected 24/7. As a result, proper lightning/surge protection with good grounding works. Is it 100 % full proofNO, but it is infinitely more effective than sticking you head in the sand with denial. You don't plan on getting into an accident but you have car insurance. Lightning surge protection is an insurance policy and another tool in your station/home safety plan.

Many hams have their station and personal electronics insured but collecting and replacing equipment is tedious and would it not be easier to prevent the damage in the first place. Due the proper diligence and you'll sleep better at night.

Member Comments:
This article has expired. No more comments may be added.
 
Lightning and Grounding  
by KD8AVA on March 30, 2006 Mail this to a friend!
Good Article.
I am no expert on grounding - in fact I'm barley a novice, but for those of us who don't have rather "large" stations, the amount of work in unplugging your antenna and power is considerably less than burrying 4 20ft ground rods etc... I am not arguing that it is a good thing to do! I think if everybody had the time and money they would have the best grounded system out there, but you my friend, are above and beyond what I will ever be in the area of grounding. Is this the same as an RF ground or different?
 
RE: Lightning and Grounding  
by K0BG on March 30, 2006 Mail this to a friend!
There is one thing you didn't mention, Michael.

There is nothing that will protect you from a direct hit except luck! Tons of amateurs get struck each year, and proper grounding saved some of them. But the fact remains, the best grounding in the world won't give you 100% protection. To assume it will is foolish folly.

Alan, KBG
www.k0bg.com
 
RE: Lightning and Grounding  
by W6TH on March 30, 2006 Mail this to a friend!
.

My goodness, how educational this post. I will keep this in mind as maybe some day it could develope into another post as this.

.:
 
Lightning and Grounding  
by WIRELESS on March 30, 2006 Mail this to a friend!
There is no lightning protection! If any typical ham antennas, transmission lines, remote tuners, and any other stuff hams use gets a direct hit, there will be nothing left, it will be vaporized except for a tower.

The surge / lightning protectors sold for use along transmission lines are a joke. They will be vaporized during a direct hit too.

By physically disconnecting the outside from the inside, you will protect your stuff and yourself. Anything else won't protect anything.

Using separate grounding for equipment helps for other issues, but it isn't going to do much for lightning protection.

There are ways to adapt lightning protection that is used in commercial broadcasting and communication towers but I have yet to see any ham willing to do what they do to protect their equipment and people from direct hits.
 
Lightning and Grounding  
by K3WVU on March 30, 2006 Mail this to a friend!
Thanks. Excellent article.

In fact, it was so good that I had to double check to make sure this was really Eham!

I'm fortunate to live in an area that doesn't have a bunch of lightning strikes. I have a decent grounding system, but I always disconnect everything when a storm approaches anyway. The only equipment I ever lost was a receiver, and that was as a result of a power line surge. Oh yes, it happened 40 years ago, so you can say I've learned my lesson.
 
RE: Lightning and Grounding  
by K8AG on March 30, 2006 Mail this to a friend!
Good article.

Of course there is no protection against a direct hit. But a lot of equipment is damaged because the ground resistance is high, even though the hit occurred elsewhere.

I used to work at an industrial complex that had control signals in perhaps 20, 50-pair cables run in conduit burried throught the facility. The longest runs were probably close to a quarter mile or so. Once in a while we would get a direct strike on or near the plant grounds. We would frequently find a small tree splintered after such an event. This would cause a voltage difference between the strike point and the surrounding ground that would basically decay through the ground around it. If the voltage difference between building grounds peaked high, we would lose a lot of equipment and I would lose a lot of sleep. The equipment was never struck directly, but proper low impedance grounding can provide a faraday shield around your equipment. That is where the benefit is. Near strikes are far more common than direct strikes.

If the cell phone companies do it, it must be profitable.

73, JP, K8AG
 
RE: Lightning and Grounding  
by K3AN on March 30, 2006 Mail this to a friend!
Outstanding article!

One cannot overemphasize the fact that a "surge suppressor" in the feedline does NOT protect against a direct hit, or even lessen the likelihood of a direct hit. It takes a heavy-duty, spread-out grounding system to safely dissipate a few hundred thousand Volts at a few thousand Amps, even if the impulse is milliseconds or less in duration.

There are two types of hams: those whose stations have had a direct lightning hit, and those whose stations soon will.
 
Lightning and Grounding  
by KN4LF on March 30, 2006 Mail this to a friend!
Very informative article. I live in west central Florida and I see on average 122 thunderstorm days per year. Using similar grounding techniques and precautions I have yet to suffer any damage to equipment in my radio shack.

--... ...--,
Thomas F. Giella, KN4LF
Lakeland, FL, USA
Grid Square EL97AW
kn4lf@arrl.net

PODXS 070 PSK31 Club Member #349
Feld Hell Club Member #FH141

Proof Of God Through Science: http://www.cosmicfingerprints.com/audio/newevidence.htm
Olivia MFSK Yahoo eGroup: http://groups.yahoo.com/group/olivia_mfsk
National Veterans Ham Radio Club: http://groups.yahoo.com/group/NVHRC
KN4LF Amateur & SWL Radio History: http://www.kn4lf.com
KN4LF 160 Meter Propagation Theory Notes: http://www.kn4lf.com/kn4lf8.htm
Man Induced Climate Change Refuted: http://www.kn4lf.com/globalwarminglie.htm


 
Lightning and Grounding  
by N8EKT on March 30, 2006 Mail this to a friend!
Very good article for this time of year.
I have been redesigning tower site lightning protection and grounding systems since 1987.
The "nothing survives a direct hit" is an unfortunate
myth that seems to keep being repeated.
I have had multiple direct hits on properly installed tower sites with no failures.
I have taken down commercial dipole antennas that were
scorched and pitted like hit with a 1000 amp arc
welder on the tip yet they continued to operate year
after year.
I only use fiberglass antennas as a side mount below the top of the tower as they do not survive a discharge well.
My top antenna is always a vhf or uhf dipole array for this reason.


 
Lightning and Grounding  
by WF7A on March 30, 2006 Mail this to a friend!
Out of curiosity, say there's a very near miss of a QTH by a ligthning strike -- is there a possibility of EMP (ElectroMagnetic Pulse) damage to the radio equipment?

Cheers,
Rich
 
RE: Lightning and Grounding  
by KB9CRY on March 30, 2006 Mail this to a friend!
I just love these types of comments:

1. "the amount of work in unplugging your antenna and power is considerably less than burrying 4 20ft ground rods etc"

2. "There is nothing that will protect you from a direct hit except luck! Tons of amateurs get struck each year, and proper grounding saved some of them. But the fact remains, the best grounding in the world won't give you 100% protection."

3. "There is no lightning protection! If any typical ham antennas, transmission lines, remote tuners, and any other stuff hams use gets a direct hit, there will be nothing left, it will be vaporized except for a tower."

My comments to the above:

1. Unlplugging your equipment will only work if you unplug every single cable and connection to the equipment and you unplug it correctly. If you unplug the coax and leave it lay on the desk, surge energy (see comments later) can still get into your house and that is a bad thing. If you unplug the coax from out side the house that may work, but what about the power cord? I guess if you flip the main breaker that will work but if you still leave the equipment plugged in surge energy may still be induced in the power wires inside of the house between the main breaker and the equipment. Then there's the notion of when do you unplug? See comments on item 2 below.

2. The first sentence is correct, you can't repel a direct strike. And the last sentence is also correct, Mother Nature can still bite you regardless of your precautions (that's why I have insurance). But, the middle sentence can be misleading. A properly designed and installed grounding system is designed to shunt virtually all surge energy away from your delicate equipmeent and precious house and send it towards earth ground, where it really wants to go. And a properly designed and installed system can also deal with direct strikes quite easily. The real concern we all should have is not that direct strike, but induced energy surges. A lightning strike a mile away is close enough to induce energy into your system to damage your equipment. When would you begin to disconnect is that's what you do? Maybe on Feb. 1? and reconnect on Dec. 1?

3. Wrong. A properly designed and installed grounding system will safely shunt all that energy to ground and your equipment will not be affected. Millions of commercial radio, TV, police, & fire department communication systems are struck each year and/or have lots of energy induced by a nearby strike and they never disconnect and they keep on ticking. It's not done by sheer luck. Lightning can be controlled if you know what you're doing. (Yes Mother Nature can and will bite from time to time; that's why we also have insurance.)

I never disconnect. I don't know if I've every been hit by a direct strike, probably have, never seen any evidence of it. Maybe my properly designed and installed grounding system has just done it's job. I do know that a strike that literally blew up the neighbor's 60 ft tall tree, 300 ft from my tower, and that induced more than a 30 amp surge into my barn's electrical, didn't affect my equipment one iota.

It can be done and it really doesn't cost that much. Play at your own risk.

Phil KB9CRY
 
RE: Lightning and Grounding  
by KD8BVJ on March 30, 2006 Mail this to a friend!
Rich, You make a very good point.

Vito, If you find it tedious discussing some of the basics of Ham Station Construction maybe you should find another web site. I know you are a legend in you own mind but we find you tedious!

This article is timed perfect for the season.
 
RE: Lightning and Grounding  
by KB9CRY on March 30, 2006 Mail this to a friend!
Out of curiosity, say there's a very near miss of a QTH by a ligthning strike -- is there a possibility of EMP (ElectroMagnetic Pulse) damage to the radio equipment?

Cheers,
Rich

Not EMP like a nuclear blast Rich but just plain old induced energy like an electric motor. As I've just posted a direct strike to my neighbor's 60 ft tall tree, 300 ft away (which literally blew up the whole top 50 ft of the tree into pieces) induced more than 30 amps of surge energy into my barn's electrical wiring because that was size of the fuse that blew. Mt tower which sat closer to the tree than the barn had my HF yagi and two VHF antennas connected to my 2M and 220 Mhz radios which were live at the time (my packet cluster connections). All I had to do is degauss the cluster computer monitor and reset the 12 v power supply to the 2 VHF radios. The HF radio and all other equipment, rotators, etc. were unaffected.

As the poster with personal experience mentioned, lightning and this surge energy can be controlled.

Phil
 
RE: Lightning and Grounding  
by KD8BVJ on March 30, 2006 Mail this to a friend!
Phillip, Keep beating your drum. Maybe you will make a difference. Posts like yours helped me understand. And so did Polyphaser's Book, and so did ICE's articles, and so did the numerous articles explaining how The US Navy handles lighting protection, or was that the US Coast Guard?

Thnaks again for covering this important subject.
 
RE: Lightning and Grounding  
by K8MHZ on March 30, 2006 Mail this to a friend!
Where is a good source of large diameter solid copper wire?

The phone company here uses #2 SBTC (Solid Bare Tinned Copper) for the grounding conductors in their MESA enclosed outdoor equipment. When we have to run it, it is provided by Verizon. Our local suppliers don't carry it.

The best we can do is #4 solid, which is tough to get on occasion as most electricians use #4 stranded bare copper. #6 solid is very easy to come by.

Something at a decent price would be cherished by many.

Great article.

73,

Mark K8MHZ
 
Lightning and Grounding  
by N0AH on March 30, 2006 Mail this to a friend!
Mike,

I live only 20+- miles from you. Fortunately, I'm lower in elevation which means I don't live too close to the Denver cyclone paths for storms.

That said, I did have a small ranch in southeast Wyoming, very much in harms way of small to major thunderstorms. After loosing a Tennadyne T-6 when it got blown off the mast, I decided to do what a lot of my contesting friends do.

I disconnect all my coax feedlines unless I know it s safe. Never a good idea to run a rig after noon during the Spring and Summer.

I put my coax onto a panel with PL 239's and have it grounded. The panel is outside.

One sunny day, N2IC was going to operate a contest from my QTH. We we're out by the 80M 4SQR when his went straight up and he got a nice static charge off the antenna. Summer is not safe.

Using 8 turn chokes on your coax is also another way I protect my station from lighting. I am not discounting grounding your antenna.

Even your rig. I have had static build up on my rig which burns a bit. Grounding it, help. Same on the amp. Still, I just disconnect until it is safe to have fun. For the most part, hamming has become a 5 month season for me-
Oct-Mar.
 
Lightning and Grounding  
by N1KDO on March 30, 2006 Mail this to a friend!
Where can I get some 20 foot long, 2 inch diameter ground rods? I have toyed with the idea of using galvanized iron pipe with a coupling, but what is the best solution to this?
 
RE: Lightning and Grounding  
by KB9CRY on March 30, 2006 Mail this to a friend!
Using 8 turn chokes on your coax is also another way I protect my station from lighting. I am not discounting grounding your antenna.

Polyphaser really warns against this type of method. I can't remember the hows and whys, check out their technical articles on Ham Station Grounding.

Too bad you're limiting yourself to just 5 months of operating; you could be year round if you chose to.
It can be done and it doesn't need to cost much.

To the other poster about wire availability.
I use #4 bare solid throughout and I purchased it from a local industrial electrical supply house. Check out the industrial yellow book in your area.
Steiner, Crescent, Englewood are a few that come to mind here in the Chicago area. You'll find nada at Home Depot or Ace.

Phil
 
RE: Lightning and Grounding  
by KB9CRY on March 30, 2006 Mail this to a friend!
Where can I get some 20 foot long, 2 inch diameter ground rods? I have toyed with the idea of using galvanized iron pipe with a coupling, but what is the best solution to this?

You don't need those, in fact, again reference the Polyphaser site, I don't think that length will add any value. I use 8 and 10 foot 5/8 diameter rods. Those I can get for a good price at Home Depot.

Phil
 
RE: Lightning and Grounding  
by W5GA on March 30, 2006 Mail this to a friend!
Great article! And I agree with KD8BVJ. Too bad all this grounding won't ground the posts from the trolls!
 
RE: Lightning and Grounding  
by AA4PB on March 30, 2006 Mail this to a friend!
Of course no lightning protection can provide a 100% guarantee that you will never sustain any damage, even from a direct hit. The fact is that most lightning damage occurs from induced currents and so a good grounding system can protect your equipment from probably 99% of the damage. It makes no sense at all to say that because you can't provide 100% protection you should provide nothing. Air bags in your car aren't likely to protect you if you are hit by a train. Does that mean air bags are useless and should be eliminated? I don't think so. The idea is to provide the best protection you can in order to improve your odds should something happen.

 
RE: Lightning and Grounding  
by KA4KOE on March 30, 2006 Mail this to a friend!
Use Cadwelds for your ground rod connections. Erico makes them.
 
RE: Lightning and Grounding  
by KB9CRY on March 30, 2006 Mail this to a friend!
Use Cadwelds for your ground rod connections. Erico makes them.

Correcto. The problem with typical ground rod clamps is that the thermal cycling between day and night, will cause the clamp to loosen and thereby losing your low resistance connection to your rod(s). Exothermic weld connections are maintanance proof (very much required for any underground connections).

CadWeld OneShots are available from industrical electrical supply houses and RF Connection

Harger also makes a similar UniShot.

Cost is no more than double that of a ground clamp (one with brass screws) and requires no maintanence.

I've seen clamps that have become very loose in less than a month.

Phil
 
Lightning and Grounding  
by KA2LIM on March 30, 2006 Mail this to a friend!
Excellent article and very good information. That said; Been there, done all that. Got hit in 1992 and all that grounding to spec's did not amount to a hill of beans. When you get hit by lighting, it goes where it wants to go and destroys everything regardless of the grounding. The previous sentence is made from experience.

Ken
 
RE: Lightning and Grounding  
by KB9CRY on March 30, 2006 Mail this to a friend!
Sorry about your experience Ken, but based on my experiences and learnings, there must have been something about your system's design that was not as it should have been or something was missed.

That said, nothing is going to fool Mother Nature all the time.

Phil
 
Lightning and Grounding  
by RADIOBOB on March 30, 2006 Mail this to a friend!
Great article, and getting good replies, thanks to all. It's one of those eham articles I save in a seperate file to go back to.

K0BG, I hated to read it, but I guess it's very true. Really is not way to insure a strike won't happen. It's scary. In the South there is news story after story, about a house going up in flames because of a hit. In the long run all that really matters is that people use smoke dectors and can get out alive, to get on the air another day.
 
RE: Lightning and Grounding  
by AA4PB on March 30, 2006 Mail this to a friend!
When you get hit by lighting, it goes where it wants to go and destroys everything regardless of the grounding
----------------------------------------------------
That's a pretty general statement. Basic electronics tells you that it will take the path of least resistance. The better you have everything bonded together and grounded the less chance you have of damage. If that were not true then cell phone companies, power stations, and TV & radio stations wouldn't waste their money on extensive grounding.

The problem with grounding is that when it works properly you generally don't know about it. It's only when it doesn't work that we see the damage. Many times we don't do it properly and then declare that grounding is worthless because it didn't save our equipment.
 
RE: Lightning and Grounding  
by K8MHZ on March 30, 2006 Mail this to a friend!
"Basic electronics tells you that it will take the path of least resistance."

This is only true with DC. AC takes that path of the least impedance.

For some reason the post I entered a bit ago from my school's Electrical Grounding book didn't make it.

I hate when that happens.

73,

Mark K8MHZ
 
RE: Lightning and Grounding  
by N6CTW on March 30, 2006 Mail this to a friend!
Rich, WF7A

I will say it this way, I lost my 10 year old Davis weather station due to "A NEAR HIT". Thank goodness, all my radio equipment was disconnected...........


Cliff, N6CTW
 
RE: Lightning and Grounding  
by NL7W on March 30, 2006 Mail this to a friend!
Yes. EMP is created by lightning, and can cause solid-state electronics, especially today's devices, to fail immediately, or seriously shorten their lifespan.

Recently, an Alaksan ham friend had most of his home's electronics fail, or within weeks, due to a very close lightning stroke. It was certainly an eye-opener for all of us - as we do not see much lightning in south-central Alaska.

Please read the following for more info:

www.ees-group.co.uk/downloads/Secondary%20Effects.pdf

73 de Steve, NL7W
 
RE: Lightning and Grounding  
by K5UJ on March 30, 2006 Mail this to a friend!
<<<3. Wrong. A properly designed and installed grounding system will safely shunt all that energy to ground and your equipment will not be affected. Millions of commercial radio, TV, police, & fire department communication systems are struck each year and/or have lots of energy induced by a nearby strike and they never disconnect and they keep on ticking. It's not done by sheer luck. Lightning can be controlled if you know what you're doing. (Yes Mother Nature can and will bite from time to time; that's why we also have insurance.)

I never disconnect. I don't know if I've every been hit by a direct strike, probably have, never seen any evidence of it. Maybe my properly designed and installed grounding system has just done it's job. I do know that a strike that literally blew up the neighbor's 60 ft tall tree, 300 ft from my tower, and that induced more than a 30 amp surge into my barn's electrical, didn't affect my equipment one iota. >>>

Phil, i've notice you always like to mention you never disconnect anything. If I were you, I'd wait until I've been directly hit a few times before I make a habit of bragging about that.

BTW, lots of professional installations such as bc stations get hit and get damaged; I guess you don't hear about them. It's called a positive strike. You may roll along and survive several negative strikes, then get a positive and kablooy.

73

rob / k5uj
 
RE: Lightning and Grounding  
by HAMMERTIME on March 30, 2006 Mail this to a friend!
Well, I know alot of people will disagree with me but I do not care. I have been running rigs for many, many years and have never, not once suffered any lightning damage and mine is not even grounded! What a waste of time. If it is going to get you there will be nothing you can do about it! I had a maple in my back yard that took a direct hit and split down the center. I have no idea how the piece that fell did not strike my dipole that was still hooked to all of my equipment via the feedline. The dipole was tied in another maple only several feet away (20-30ft) and the strike damaged absolutely nothing but the maple!!!
 
Lightning and Grounding  
by K0HEA on March 30, 2006 Mail this to a friend!
Ah yes, grounding!

I will be an Extra by the time I figure out just how to properly ground my equipment and antenna (within HOA restrictions).

I live in a second floor condo, and the patio unfortuately has wood railing and a concrete deck (which I cannot drill into).

I cannot for the life of me figure out grounding both inside and out.

Help?

Herb K0HEA
 
RE: Lightning and Grounding  
by RobertKoernerExAE7G on March 30, 2006 Mail this to a friend!
TKs for the article Michael.
73 OT
Bob
 
RE: Lightning and Grounding  
by K5UJ on March 30, 2006 Mail this to a friend!
BTW, my comments to Phil were intended to be friendly chiding, and I like others, appreciate his comments.

rob / k5uj
 
RE: Lightning and Grounding  
by KD8BVJ on March 30, 2006 Mail this to a friend!
Hammertime, Think about it? Where do you live? What is the mean # of strikes for your area? Are you above the average height above sea level? Are you Lucky??? Scientists and engineers have recomendations for Comm Sites!! Do you think that you and your equipment and your family are protected? I wish you all the best!

Good Luck!!
 
RE: Lightning and Grounding  
by W3ZD on March 30, 2006 Mail this to a friend!
Great article and very timely. I cannot agree more with every phase of grounding that you have covered. I did install a trunking system a few years back and insisted on grounding just as you described. There were a few that said that is was over kill but after insisting that they read the information that you susgested they were ready to do a bit more that I had wanted. We never had an outage from a lightning storm!

Yes, there is nothing to keep ole Thor from sending a jolt your way and when it comes, what ever is connected will be toast. The intent of this article is to get across to all that lightning does as it wants but there are a few things that you can do to make a possible disaster a bit smaller.
 
RE: Lightning and Grounding  
by AA4PB on March 30, 2006 Mail this to a friend!
Hammertime, my dad drove a car for around 60 years without ever wearing a seat belt and he was never injured in an auto accident. Does his luck mean that seat belts are a waste of time for everyone?
 
RE: Lightning and Grounding  
by W4CNG on March 30, 2006 Mail this to a friend!
Nice article Mike. You folks down in Florida and other areas that have a sand mix in the ground, remember after a few strokes that sand turns into GLASS around your ground rods and they are very well insulated from what they do. That is why we in the Commercial business do semi-annual checks on ground resistance to catch the insulation problem and ADD more ground rods to the system. Testing ground systems in a multi-user environment is another different topic all together. I have seen a few of the towers where some of my company's equipment is installed take direct strokes and visited the site a few minutes after the storm has passed and seen ZERO damage inside. Another key in the lightning issue is DC Ground antennas, plus all the other measures to insure lightning goes straight to ground. This also includes that all grounding connections go down to the ground rods. Lightning does not go back UP to a ground. The connection points for all surge and grounding connections to antenna cables must go straight down to the ground ring and rods. Also do not use cad-welds inside, it will really stink up your shack.

Steve W4CNG
 
RE: Lightning and Grounding  
by KC8VWM on March 30, 2006 Mail this to a friend!

...Different strokes for different shacks?
 
RE: Lightning and Grounding  
by W6TH on March 30, 2006 Mail this to a friend!
.

KD8BVJ, Gary

Thanks for your love and pursuit of wisdom by intellectual means and moral self-discipline.

.:
 
Lightning and Grounding  
by K2JVI on March 30, 2006 Mail this to a friend!
One note about the #4 solid ground wire- I purchased some at my local Home Depot and I think it's still available.

Three years ago we did a major addition-remodel to our house and the electrical was upgraded as well. In addition to the 200 amp service, I redesigned the ground system. I ran a 30' run of #4 solid at the footing level of the addition along with 8 10' ground rods at the same level. In addition, I have a #6 loop with four ground rods close to the surface, this loop provides bonding for my telephone,TV antenna, and satellite dish. One reason the Home Depot would carry #4 ground wire is that per NEC- #4 copper is the size required for the grounded conductor between the main panel and the cold water pipe.
73's..
 
Lightning and Grounding  
by W7LV on March 30, 2006 Mail this to a friend!
I'm a Believer. July, 1982, I saw the hit on my 58' Rohn fold-over in SW Florida from 5 miles away. The only electronic things that survived the hit were some old tube-type rigs. All the solid-state stuff and the (then-new) PC gear either got smoked, welded together, or disappeared.

And the coax was grounded at the time. As was the rotator wire. All that damage was via the power mains.

Fortunately, my Homeowners' policy paid off. The inventory and receipts made all the difference in the world.

Surge suppressors? Gimme TWO!
Ground rods? Hey, I'll HIRE someone to pound it in!
 
RE: Lightning and Grounding  
by KC8VWM on March 30, 2006 Mail this to a friend!
Ground rods? Hey, I'll HIRE someone to pound it in!

----------

Hey, I love poundin'
 
RE: Lightning and Grounding  
by KO6UJ on March 30, 2006 Mail this to a friend!
KD8AVA,

You asked, "Is this the same as an RF ground or different?"

An electrical ground CAN be an RF ground, but usually it is not. For good information on RF grounds and RF in the shack issues check: www.radioworks.com.

Most second story or higher shacks have RF ground issues. My shack is one, or I should state that it WAS one. The lack of a good RF ground is usually the culprit for all types of RF demons. Even if you have a horizontal antenna, there is a need for a good RF ground. It's more evident with a vertical. In fact, most stations have RF in the shack issues on one frequency or another. It's simply less prevalent on some. Think "counterpoise" for both horizontals and verticals.

Many hams believe that a station cannot function well without an electrical ground. Let's say that a good electrical good is preferred, but not necessary for a good signal.

OTOH a good RF ground is necessary for good RF out. Some hams believe that RF output is impossible without a good electrical ground. That is an incorrect assumption on their part.

The proof is simple . . . the International Space Station has a great signal without an electrical ground. An earth ground for them would require a rather long ground rod . . .
 
Lightning and Grounding  
by WA6BFH on March 30, 2006 Mail this to a friend!
Good thoughts! Thanks for the tips and company contact info!

Since Im now installing a 200 Amp electrical service for my new QTH in DM15ej {getting rid of those two 30 Amp fuses, and the knife switch on the original service), I will add the Intermatic surge suppressor. Since I am also putting up two towers, I will think about a good grounding scheme too!

Gotta protect all those vertically polarized 6 Meter antennas, huh Caity?


73! de John
 
RE: Lightning and Grounding  
by K9KJM on March 31, 2006 Mail this to a friend!
A VERY good post! To K8AG, K0BG, Wireless, And others who clearly did not read the entire post:
Direct lightning strikes CAN be taken and suffer NO damage!!! Did you miss the part about cellphone towers, Police, Ambulance, Fire, Commercial radio, etc etc NOT "disconnecting" at every hint of a storm?

I too take several DIRECT lighting strikes to my tower every year. WITHOUT any damage.
YES, It is a big project to properly protect from direct hits. NO, It does not have to cost a fortune.
Instead of Cadweld, Silver solder can be used, Flowed with MAPP gas from a small hand held torch, USED copper can be obtained for a fraction of what new costs, etc etc.
For a great site that provides good up to date info on PROPER lightning protection see: http://members.cox.net/pc-usa/station/ground0.htm
I sure hope that those who still think that "NOTHING" can withstand a direct lightning strike take the time to READ the FACTS before passing along those old wives tales!
 
Vicks Solder Vapo-Rub  
by KA4KOE on March 31, 2006 Mail this to a friend!
Wouldn't solder of any kind, silver or lead, etc., vaporize on a lightning stroke? Cadwelds are just that. Welds. The ground conductor and ground rod are melted into each other rapidly and completely, with no voids for corrosion to form in.
 
RE: Vicks Solder Vapo-Rub  
by KB9CRY on March 31, 2006 Mail this to a friend!
Yes soldering of any type is not recommended. One good surge event and the solder will melt. Dont' be confused; NEC and all the lightning product companies only require or recommend a mechanical or welded connection.

To Rob who (in part) wrote:
"Phil, i've notice you always like to mention you never disconnect anything. If I were you, I'd wait until I've been directly hit a few times before I make a habit of bragging about that."

I don't take anything said on this site personally. If my grounding system is properly designed and properly installed and maintained, how will I know if I've taken a direct hit?

All the energy will have been shunted properly to ground. I do see arc pitting at the top of the masts on the tops of the towers, are those evidence of hits? I've personally never witnessed a hit. I've watched out the back door with lightning dancing all around the sky above, cloud to ground strikes and horizontal cloud to cloud strikes and nada. Maybe my grounding is successfully bleeding off static buildup which is seen as required to complete the circuit? I do know about the neighbor's tree and my barn's 30 amp circuit getting zapped. I've talked extensively with the PolyPhaser and ICE folks (I use all ICE equipment.) and they've all commented that I'm doing things as suggested. I just have too many antennas, cables, rigs, etc. to even entertain any type of disconnection.

(Here's my website; my labor of love. Click on the buttons in upper left.)

http://nidxa.org/memberWWW/kb9cry_home.htm

Maybe I have been really lucky and haven't encountered the "Perfect Strke"? I'd like to think that my luck is a result of hard work!

Phil KB9CRY


 
Lightning and Grounding  
by K9MI on March 31, 2006 Mail this to a friend!
This is a great thread I seem to read about grounding and come away with more questions then answers. For example, I've read many many articles that mention all grounds need to be bonded, even to your electrical service ground. In my case, I have an 8ft ground rod as close to the shack as I can get it, using stranded, insulated #4. My tower is only 40ft. I knew very little on grounding the tower at that time, and my helpers (other hams) didn't seem to know much either. Now, onto the electrical service ground, with the telephone and dish (tv) grounds connected to each other on the other side of the house.

I realize this all needs bonded together. My question is, what is the policy of your insurance company, if they see the tower ground attached to the utility ground, if the strike was to your tower? Are they inclined to blame you since your tower was attached to your utility grounds?

I do have a non active ham friend who is a broadcast engineer, and his antennas/towers get hit all the time with no damage. Maybe I should kidnap him for a few hours and layout a plan to make things as safe as possible.

73, Mike K9MI
 
RE: Lightning and Grounding  
by KB9CRY on March 31, 2006 Mail this to a friend!
Great questions Mike.
First go to the Polyphaser site(www.polyphaser.com) and read their technical article on Ham Station Grounding (or something like that). After reading it once, read it again.

"For example, I've read many many articles that mention all grounds need to be bonded, even to your electrical service ground. In my case, I have an 8ft ground rod as close to the shack as I can get it"

This is your SPG (single point ground).

"using stranded, insulated #4." "My tower is only 40ft."

Get rid of that stranded stuff and use solid #4 or 2-3 inch wide copper strip. Oxidation between the strands will cause high resistance/impedance and reduce the current carrying capacity. Braid is also bad for the same reason.

I knew very little on grounding the tower at that time, and my helpers (other hams) didn't seem to know much either.


Not surprising many are clueless or become helpless to even think that a strike can be controlled.


"My tower is only 40ft."


Doesn't matter on height. Anything outdoors can have surge energy induced into it and/or receive a direct strike.

The tower should be grounded. Separate ground radials for each leg, each radial made of #4 solid, with ground rods located at the tower base and then every 2X the rod length going out at least 50 ft to a max of 75 ft. A ground rod located at each guy anchor if your use conductive guys is also required. Then at least one of these radials should also be extended and tied to your SPG.


"Now, onto the electrical service ground, with the telephone and dish (tv) grounds connected to each other on the other side of the house."

You tie your SPG, routing outdoors, around the house (avoid sharp bends) and connect with #4 solid to your electrical ground.

"I realize this all needs bonded together."


Also, every cable that comes in from the tower should be routed through a lightning arrestor whose ground is also connected to the SPG.


"My question is, what is the policy of your insurance company, if they see the tower ground attached to the utility ground, if the strike was to your tower? Are they inclined to blame you since your tower was attached to your utility grounds?"

No, they will congratulate you for properly following NEC codes.

"I do have a non active ham friend who is a broadcast engineer, and his antennas/towers get hit all the time with no damage. Maybe I should kidnap him for a few hours and layout a plan to make things as safe as possible."

Yes do that. Now many hams are just plain lucky and those are a possible danger to themselves and to others. In life, we all assume a level of risk. It's up to each to determine what level you're comfortable with.

Phil
 
Lightning and Grounding  
by K9MI on March 31, 2006 Mail this to a friend!
Thanks for all the info Phil. One thing, I might have stated wrong that I want to get straight. Is my spg just outside my shack, or is it or is it where my utility ground is, on the other side of the house?

Also, inside the #4 stranded connects to a 5ft copper pipe I have on the back of my desk. I'm using braid, and connected each piece of equipment directly to that pipe with the braid off of some old RG8. The each piece of equipment connects to the pipe individualy. No equipment is daisy chained together and then goes to the pipe. It's each piece straight to the pipe, which has the stranded #4 connected to it, and out to my ground rod, right outside the shack.

Close, or do I need to make some changes there also?

Thanks... Mike, K9MI

 
RE: Lightning and Grounding  
by W8JII on March 31, 2006 Mail this to a friend!
To Hammertime; Grounding a waste of time???????????????
You gotta love that kind of attitude. Do you enjoy a good game of Russian Roulette also? 73, Ron, and oh yeah, good luck. Eventually you're gonna need it!
 
RE: Lightning and Grounding  
by KB9CRY on March 31, 2006 Mail this to a friend!
Thanks for all the info Phil. One thing, I might have stated wrong that I want to get straight. Is my spg just outside my shack, or is it or is it where my utility ground is, on the other side of the house?

The SPG is just outside your shack. You then route a wire #4 bare solid around the house over to the utility ground.


Also, inside the #4 stranded connects to a 5ft copper pipe I have on the back of my desk.

That's what I do also, I have a piece of 1/2 inch copper pipe attached to the back of the desk and each piece of equipment has a separate ground wire connected from the equipment ground lug to that pipe.

I'm using braid, and connected each piece of equipment directly to that pipe with the braid off of some old RG8. The each piece of equipment connects to the pipe individualy. No equipment is daisy chained together and then goes to the pipe. It's each piece straight to the pipe,


Personally I also use braid indoors only but I believe most folks would recommend to get rid of that and use solid wire, like 12 gauge.

which has the stranded #4 connected to it, and out to my ground rod, right outside the shack.


Correct, just replace the stranded with solid.

Close, or do I need to make some changes there also?

Sounds like you're doing well so far.
 
RE: Lightning and Grounding  
by K8MHZ on March 31, 2006 Mail this to a friend!
Some info from my NJATC Electrical Grounding book:

First, they are very clear that it is better to increase the length of a grounding rod than it is to increase the diameter.

They discuss a grounding electrode that may appear to be a 2 inch rod. It is called a electrolytic ground rod which is actually a 2 inch copper/nickel alloy pipe filled with salts and surrounded by volcanic clay. These rods are very low impedance and are used to get the grounding system below 5 ohms impedance. The NEC allows for 25 ohms. It is very difficult to get below 5 ohms with solid grounding rods, no matter how many there are.

You can measure the resistance of a grounding electrode with a Megger and three rods. The problem is that a distance of 100 feet between the outside rods must be maintained to get an accurate reading.

Grounding systems created for use other than the mains power supply (communications equipment, lightning supression) must not only be bonded together, but must be bonded together by 'external means' as covered in Section 250-92.

Section 250-62 requires that lightning rods have their own ground rods in addition to the mains rods. Connecting lightning rods directly to the mains grounding rods is a violation of the NEC.

Other systems such as telephone and communications are permitted, but not required to have their own grounding electrodes.

From other sources I have pretty much found that it is agreed that the best grounding conductor is 2 or 3 inch wide flat copper strap. Following flat copper strap is TINNED flat braided copper strap. Non-tinned braid such as that made out of coax shielding is fine for inside the shack where is can stay nice and shiny. Next we have solid copper wire. The thicker the better, with a minimum of #4. Verizon uses #2 Solid Bare Tinned Copper. After that we have large diameter stranded wire which probably will not satisfy the requirements of most installations, especially over time.

It has been shown that copper strap, 2 inches wide, can shunt direct lightning strikes without fusing open.

Anyone that has been through Skywarn training has probably seen the video of the telephone pole getting struck by lighting and turning the grounding conductor into vapor. The pole remained intact, but now unprotected from a further strike.

A very good technique for protection is the 'grounding window'. This is a copper plate place so that one side is internal and the other external. This plate is solidly grounded to a system of rods starting as close to the plate as possible. All feedline is passed through this window and grounded by bulkhead connectors at a minimum, or PolyPhasers if you need superior protection.

The grounding conductor is also passed through the plate and mechanically connected to it at that point. The conductor needs to be kept as short as possible. The exact technique for grounding the plates and the arrangements of the conductors and rods will vary with several factors, mostly based upon conductor distances and the resistance of the Earth at the station.

The best grounding electrode system to be found has to be installed at the time the building is built. 20 foot or longer copper ground rods are driven at intervals where the concrete is to be poured. They are all connected together with a conductor and are also conncected to the re-bar. A low impedance conductor is left accessible as the pour will cover and encase the system. The preferred system, a Ufer, uses 1/2 rods as the inter electrode conductors, CAD welding them together to form a three dimensional copper contact system. It is preferred that the inter-electrode conductors are at least 20 feet long.

There is a way to test the resistance of a grounding electrode without a Megger. It is dangerous and not very accurate, but it can tell you if you are even close to your goal. A load, like a light bulb, is connected across the 120 hot line and the UNBONDED (for this test only) electrode system. Measuring the current and doing some math will give you the resistance. The problem arises that you are only testing the resistance between your electrode system and the mains, not the resistance between your electrode and solid ground. We are assuming, for the purpose of the test, that the mains are effectively grounded.

The integrity of every connection is crucial. Connections oxidizing over time can greatly reduce the effectiness of the system, creating potential for damaging amounts of heat to build up at high impedance connections. What may work fine in a nice dry shack may fail quickly in an outdoor or underground environment.

Good topic, if someone is kept safer by the info provided in this forum we have a true winner here.

73,

Mark K8MHZ

 
RE: Lightning and Grounding  
by KB9CRY on March 31, 2006 Mail this to a friend!
The proper way to test your ground system is to use the "Fall of Potential" method (there may be other methods) and you must use the proper instrument to do that. If you desire more info, search either the Biddle or Fluke websites since they make those devices.

At the chemical plant where I'm an engineer, we do separate tests for the grounding clamps to the local grounding buss, from the buss to the ground rod system, and then for the rods to the soil.

It's actually not hard to achieve continuity less than the 25 ohms specified by NEC.

Phil
 
RE: Lightning and Grounding  
by KG6WLS on March 31, 2006 Mail this to a friend!
--Lightning and Grounding--

Just a quote: "Lightning is one of the most beautiful displays in nature. It is also one of the most deadly natural phenomena known to man. With bolt temperatures hotter than the surface of the sun and shockwaves beaming out in all directions, lightning is a lesson in physical science and humility".

Can a direct lightning hit to ones tower, antennas, or equipment be avoided, grounded or not? Well, only time will tell (depending where you live).

Disclaimer: Before anyone gets wrapped around the axle... this is not an opinion, nor is this how every ham should have their station set up, nor is this intended to be a poke in the eye to the EE's who are amateur radio ops. The article below comes from the NEC (National Electrical Code). To some, this is only a minimum requirement to meet code. To others, these practices are either overlooked or simply put...a moot point. And, no. The electrical "code police" will not come banging down your door if they see an antenna farm.

But, here it is anyway for those who don't have a copy of the NEC, or use it just to prop up the front of the radio so that you can see the display better. Again, this is not MY opinion. Just something to be shared and read to those who have interest. The areas covered are specifically intended to the original topic at hand. I won't cover the entire article.

-----------------------------------------------------

Article 810 - Radio and Television Equipment

A. General

810-1. Scope. - This article covers antenna systems for radio and television receiving equipment, amateur radio transmitting and receiving equipment, and certain features of transmitter safety. This article covers antennas such as multi-element, vertical rod, and dish, and also covers the wiring and cabling that connects them to equipment. This article does not cover equipment and antennas used for coupling carrier current to power line conductors.

Article 810-15. Grounding.
Mast and metal structures supporting antennas shall be grounded in accordance with Section 810-21.

Article 810-20. Antenna Discharge Units - Receiving Stations.
(a) Where required. - Each conductor of a lead-in from an outdoor antenna shall be provided with a listed antenna discharge unit.

Exception: Where the lead-in conductors are enclosed in a continuous metallic sheild that is either permanently and effectively grounded or is protected by an antenna discharge unit.

(b) Location. Antenna discharge units shall be located outside the building or inside the building between the point of entrance of the lead-in and the radio set or transformers, and as near as practicable to the entrance of the conductors to the building. The antenna discharge unit shall not be located near combustible material or in a hazardous (classified) location as defined in Article 500.

(c) Grounding. The antenna discharge unit shall be grounded in accordance with Section 810-21.

Article 810-21. Grounding Conductors - Receiving Stations. Grounding conductors shall comply with (a) through (j). (( I'll just cover (h) through (j) ))

(h) Size. The grounding conductor shall not be smaller than No. 10 copper, No. 8 aluminum, or No. 17 copper-clad steel or bronze.

(i) Common Ground. A single grounding conductor shall be permitted for both protective and operating purposes

(j) Bonding of Electrodes. A bonding jumper not smaller than No. 6 copper or equivalent shall be connected between the radio and television equipment grounding electrode and power grounding electrode system at the building or structure served where separate electrodes are used.

810-57. Antenna Discharge Units - Transmitting Stations.
Each conductor of a lead-in for outdoor antennas shall be provided with an antenna discharge unit or other suitable means that will drain static charges from the antenna system.

Exception No. 1: Where protected by a continuous metallic shield that is permanently and effectively grounded.

Exception No. 2: Where the antenna is permanently and effectively grounded.

810-58. Grounding Conductors - Amateur Transmitting and Receiving Stations.
Grounding conductors shall comply with (a) through (c)

(a) Other Sections. All grounding conductors for amateur transmitting and receiving stations shall comply with Sections 810-21(a) through (j).

(b) Size of Protective Grounding Conductor. The protective grounding conductor for transmitting stations shall be as large as the lead-in, but not smaller than No. 10 cooper, bronze, or copper-clad steel.

(c) Size of Operating Grounding Conductor. The operating grounding conductor for transmitting stations shall not be less than No. 14 copper or its equivalent.

-----------------------------------------------------

So, there it is. You can take it seriously, or with a grain of salt. It's not my opinion, so you can throw flames/pot-shots all you want. It's just a section out of a book (like any other book ie.: The ARRL Antenna Book, The ARRL Handbook for Radio Communications, etc.)

BTW: Welcome back John (WA6BFH). It's good to see your wit and humor back again! :)

--... ...-- to all!
Mike



 
RE: Lightning and Grounding  
by K8MHZ on March 31, 2006 Mail this to a friend!
"The proper way to test your ground system is to use the "Fall of Potential" method (there may be other methods) and you must use the proper instrument to do that."

Thank you. Visit www.megger.com and check out "Getting Down to Earth"

BTW, If you follow both the NEC and Part 97 to the letter you will be the worst amateur radio operator allowed by law.

Those provisions are indeed bare minumums and may not be sufficient to meet the needs of every installation. Neither publications allows for future expansion.

The provisions of the NEC were met through compromise between opposing factors, the insurance industry and the construction industry. As such, those minimums are a compromise as well.

If you want a good installation, consider the current carrying capabilities of a code minimum installation to be half of that desired. If the code allows a #10, a #6 is probably a better choice. If a #6 is allowed, I am shooting for a #2.

"The electrical "code police" will not come banging down your door if they see an antenna farm."

Here the electrical "code police" or the Code Nazis as they are lovingly referred to by most of the hack rats around here, build antenna farms. Our Chief Electrical Inspector is Don WB8I and is a walking code book. He is very strict and great to work with. I know that if Don signs off on my work the people in the building I just wired up are safe.

Most don't know that there is also a minumum guage for wire antennas. It is #14 for short spans and #12 for longer ones. Part 97 and the ARRL training books don't cover the issue. Dollar store speaker wire used for antennas is a code violation.

Bear in mind that any claim made to an insurance company that can be related to an illegal installation will have good reason not to be paid, and most likely will not be paid.

Gotta go...I hear thunder..

73,

Mark K8MHZ

"Real electricians glow in the dark"



 
RE: Lightning and Grounding  
by AA4PB on March 31, 2006 Mail this to a friend!
Bear in mind that any claim made to an insurance company that can be related to an illegal installation will have good reason not to be paid, and most likely will not be paid.
---------------------------------------------------
People keep posting that. Does anyone personally know of an actual instance where an insurance company refused to pay a claim because the residence was not up to the NEC?
 
Lightning and Grounding  
by AI8H on March 31, 2006 Mail this to a friend!
Lightning is good - it burns off old brush in the forest and creates life on young planets.

Lightning is bad - if one leaves electronic devices in its way.

It will find its way.
 
Lightning and Grounding  
by KU2US on March 31, 2006 Mail this to a friend!
Everyone is right. Lightning is so variable and unpredictable. I live in Western NY. 30 miles south of Rochester,(Not your lightning hot-spot) and was struck directly once-wasted ALL of my station, grounding didnot matter, and once by static electricity-A direct hit on my neighbors 100' cottonwood tree that demosished the top 50% of it. It was 70' away from my home. With this one, electricity entered my G5RV 75' up, also entered my house electrical system and wasted and melted some in-wall wiring. Im lucky I didnot have a fire. None of my station was affected because I unplugged it from the AC and antenna coax and placed the end of the coax in a glass jar (old wives tale-maybe?)..I listen to NOAH-I knew the thunder storms were comming. I will agree that you can never ground enough. I am more affraid of electrical spikes and surges from the AC-no warning there. All electrical home systems are grounded, but the static electricity from my neighbors strike fused the breakers and kept on going. I have a steel roof which was grounded, all AC plugs are grounded, the breaker box is grounded, everything is grounded-It didnot matter in this situation. I know extra precautions can be taken, and I will, BUT-NOTHING can stop mother nature, no matter what you do..You can only lessen the hurt.
 
RE: Lightning and Grounding  
by K8MHZ on March 31, 2006 Mail this to a friend!
"People keep posting that. Does anyone personally know of an actual instance where an insurance company refused to pay a claim because the residence was not up to the NEC?"

Actually, that is a great question.

I don't personally know of anyone, but I hear it from inspectors.

A personal post would help to verify the assertion.

But, as an insurance adjuster, would you pay off a claim that was a result of someone not following the law?

73,

Mark K8MHZ
 
RE: Lightning and Grounding  
by K8MHZ on March 31, 2006 Mail this to a friend!
"I listen to NOAH"

I HOPE you meant "I listen to NOAA"

73,

K8MHZ
 
Lightning and Grounding  
by W8QW on March 31, 2006 Mail this to a friend!
Mike:

Great article. One thing I need to ask. I live in an area where the soil is nearly all sand. The water table is approximately 10 - 12 feet below ground level. Does this have any effect on the ground system as you described it?

Again, great article and 73's.

Dave, W8QW
 
RE: Lightning and Grounding  
by KX8N on March 31, 2006 Mail this to a friend!
"But, as an insurance adjuster, would you pay off a claim that was a result of someone not following the law?"

The obvious answer to that would be "no", but I guess it would depend on if you got CAUGHT not following the law. Let's say you have a lightening strike. You lose your station, computer, etc. because you had a copper wire running from your rig to your second story cold water pipe. If the adjuster doesn't notice the wire going to the pipe, or you realize your mistake and remove it, I suppose they would pay.

But no, if the insurance company sees an obvious violation of the electrical code or anything else that shows you were negligent, I don't think they'd pay.

Dave
KX8N
 
RE: Lightning and Grounding  
by K6IHC on March 31, 2006 Mail this to a friend!
I live in coastal Calif, with one of the lowest annual incidences of lightning in the country (aren't I fortunate?).
At the present time, my station's lightning protection is minimal. But I have most of the hardware already collected to peform the remainder of the work when the rains let up (which around here, late fall to early spring is usually the t-storm *season*).

The main problem around here is lightning-induced surges on the AC mains. A couple of years ago, I had an IC chip ($1.50 chip) in my Astron RM-35 zapped by a surge over the AC lines. The lightning was several miles away, as noted by the time delay from the flash to the thunder.

My antenna protection system will consist of the typical ground rod (already driven last year), #6 solid wire, clamps, inline co-ax suppresors (Polyphaser and Alpha Delta), and bonding to the house AC ground. The place where I plan to really concentrate my efforts is in the house AC line protection.

Thanks for reminding me about the work I need to finish in the next few months...
 
RE: Lightning and Grounding  
by NS6Y_ on March 31, 2006 Mail this to a friend!
Go check out www.microwaves101.com and look at the Microwave Mortuary, some nice lightning hit photos. And..... other stuff. My favorite of all time is the little SMD cap that fried, and looks like one of those halloween "snakes".
 
RE: Lightning and Grounding  
by KB9CRY on April 1, 2006 Mail this to a friend!
Ken, I'm sorry for your past experiences and I don't mean anything personal but I'd like to use your comments as an example. Also, hopefully we all keep learning.

Ken wrote:
"I will agree that you can never ground enough. I am more affraid of electrical spikes and surges from the AC-no warning there. All electrical home systems are grounded, but the static electricity from my neighbors strike fused the breakers and kept on going. I have a steel roof which was grounded, all AC plugs are grounded, the breaker box is grounded, everything is grounded-It didnot matter in this situation. I know extra precautions can be taken, and I will, BUT-NOTHING can stop mother nature, no matter what you do..You can only lessen the hurt."

Here is an example of being confused about the differences between different types of grounds and their purpose and capabilities. Yes your breaker box and AC outlets are grounded but that is the electrical or safety ground designed to prevent electrical shorts and electrical fires in the house and prevent electrocutions. But, they are not lightning grounds. Now what would be needed is either a whole house lightning surge/arrestor system or individual AC arrestors on the AC circuits connected to your equipment. You really can totally protect yourself, you just need to cover ALL the bases and do it properly. Any one thing missed, Mother Nature can gotcha! Phil
 
Lightning and Grounding  
by WA1RNE on April 1, 2006 Mail this to a friend!
Mike;


Nice job, this is useful information to all hams.


For this reason, I've always been a proponent of a good station grounding system.


Unfortunately, many hams don't follow these guidelines, probably due to several factors such as mis-information, station/property conditions for creating a good low impedance ground system and in some cases, cost, especially if the station is far removed from an outside wall and the outdoor grounding system.


73, Chris
 
RE: Lightning and Grounding  
by AA4PB on April 1, 2006 Mail this to a friend!
But, as an insurance adjuster, would you pay off a claim that was a result of someone not following the law?
-----------------------------------------------------
Houses burn down because people overload extension cords with Christmas tree lights and the insurance company pays. Years ago I had a lady staying in my house to take care of the kids. She was smoking in bed and burned out the bottom floor. Knowing that was the cause, the insurance company paid for the repairs and even paid for her personal clothing. Insurance companies pay every day because someone had an accident while speeding or breaking some other law or weren't wearing their seat belts.

Of course I'm not proposing that we should knowingly violate the NEC but I do question whether it is a foregone conclusion that if you have a claim the insurance company is going to investigate to ensure that your ham installation meets NEC before paying the claim. Now after paying a claim I can see them threatening to cancel your insurance if you don't correct the problem - but I don't personally know of a case where even that happened.
 
Lightning and Grounding  
by N0RTU on April 1, 2006 Mail this to a friend!
While I'm not going to get into the debate of whether to ground or not, I'd like to say that those here who are in favor of using exothermic welds(Cadweld or similar) to make connections in grounding conductors are right on. Their intended use is for connections that are to be buried in soil. Mechanical (compression or bolted) connections are not rated to be buried in earth and will deteriorate relatively quickly over time. I've worked for electrical contractors and utility companies in electrical power substations, high voltage switchyards, and in power plants. Exothermic welds are standard fare in these facilities. Conductors large (500MCM) and small (#6) that are meant to contact the earth or to be buried are REQUIRED to be joined with the Cadweld process.
I've dug up ground rods and copper wire that have buried for more than 25 years to find that the condition of the connections were excellent.
The only downside that I can find to the exothermic weld process is that it can be very dangerous. While welding, temperatures can exceed 1000 deg. F and there is an expulsion hazard which can occur if moulds for Cadwelds are not dried properly before use.
For those who might wish to use the exothermic weld products to install their ground system, please be warned that you DEFINITELY need to read ALL of the warnings and instructions that come with these products and follow them to the letter. Proper clothing including sturdy cotton work jeans/overalls and long sleeve cotton shirts should be worn. Leather gloves and eye protection are a MUST. Just one mishap with these welding products can permanently take a persons eyesight, or even worse.
I'm not trying to discourage the use of these welds, but I've seen two mishaps, and they were very serious.
If you are not the kind of person who can read and follow instructions, don't use these products.
For those who are willing to "play by the rules", there is no finer way to build a grounding system that will perform very well.

Best wishes and safe hamming to all
Mike
 
RE: Lightning and Grounding  
by KD8BVJ on April 1, 2006 Mail this to a friend!
I have to say I agree with everything AA4PB and N0RTU just said.

This has turned into one of the best posts I have seen in a long time.

This post is about safety and common sense and these things can not be said often enough!
 
Lightning and Grounding  
by WA8MEA on April 1, 2006 Mail this to a friend!
I was taught at age 10 that nothing would survive a direct lightning strike. So I disconnect EVERYTHING.

I use to place the connectors into glass jars. I have NO IDEA where I picked that up from! Anybody have a guess? I suppose some ham I respected told me about it. Or I must've read it somewhere years ago.

Recently, our Village Community Church put a huge metal ern on top of the steeple. It contains the ashes of the deceased organist. There's also a wonderful metallic wind vain attached to the ern. The church is on the highest hill in the village.

Last night I could've sworn that lightning bolt hit "her" and blew her ashes all over the village! Instant lightning/thunder combo!

Drove by the church this morning and all was intact. Maybe next time....

73, Bill - WA8MEA
http://HamRadioFun.com
 
RE: Lightning and Grounding  
by AA4PB on April 1, 2006 Mail this to a friend!
Bill, I was taught a lot of things at a young age and some of them turned out not to be true :-) There is nothing wrong with disconnecting everything from the rigs PROVIDED the coaxes remain grounded at the entry point. If you are counting on sticking the end of an ungrounded coax cable into a glass jar to protect you then you are very mistaken. Think about it for a minute. We know that lightning can jump thru thousands of feet of air so why would 1/8-inch of glass stop it? Even if the glass could stop it, what would keep it from jumping out the uncovered top? If you completely seal the jar, what would keep the very high voltages from arcing thru the plastic insulation on the outside of the coax? I think this glass jar thing is an "old wives tale" that has no technical basis.

Unless you disconnect your coax, rotor cables, etc. and pull them well outside the house (and can ensure they are that way during any lightning event) then you NEED a grounding system.
 
Lightning and Grounding  
by WB5EKW on April 1, 2006 Mail this to a friend!
Most excellent presentation, Mike.

Just how did you install those 21 - 8 foot ground rods and the 20 foot 2 inch pipes? Sledgehammer? or something a bit more easier perhaps??

73
WB5EKW - Howard
 
RE: Lightning and Grounding  
by N5PVL on April 1, 2006 Mail this to a friend!

When there is any possibility of lightning, I have no enthusiasm whatsover for getting near antenna connections.

The rig may cost several thousand bucks, but I am priceless.

So are you, so don't go fooling around with antenna connections while a storm brews outside the shack.

Have you looked up price and availability on a new you lately?

Charles, N5PVL

 
RE: Lightning and Grounding  
by W3ZD on April 1, 2006 Mail this to a friend!
I can remember one night I was in the shack and had removed the coax from my hf rig and was doing something on the computer and kept hearing a small zap ... zap every so often. Turned the lights off and noted sparks jumping the PL 259! Never did get violent, but still a reminder what goes on IF you do not unplug things.

Clayton
 
RE: Lightning and Grounding  
by NB3O on April 1, 2006 Mail this to a friend!
One of the best resources for illustration and explanation of grounding can be found in Motorola's R56 Standards and Guidelines for Communications Sites, part number 68P81089E50-A, available both on compact disc and hard copy. It's not cheap, however it is a good investment for a club and is the basis for most cellular installations.
As mentioned earlier, Erico's Cadweld is easy to use and provides a bond rated for the life of the conductor. One of our favorite suppliers is The RF Connection (www.therfc.com), attention to Joel. Erico provides almost every conceivable weld mold, however finding the part numbers are sometimes difficult for the semi-custom molds (round tower members, terminal lugs, etc). Joel is pretty good at sorting these out. He also has a source for 1-1/8" hex shank ground rod (5/8") drivers for use in most air or electric jack hammers.
73, NB3O
 
RE: Lightning and Grounding  
by K6AER on April 1, 2006 Mail this to a friend!
Gentleman,

My next posting will be on putting a 20 foot ground rod into the ground. I have done it several ways and it depends on the type of soil and your budget. Some methods are harder than others and all require patience. I realize this is a passionate subject and I have enjoyed the posts.

Today we had our first lightning storm in Colorado...let the fun begin.

Mike - K6AER
 
Lightning and Grounding  
by K0ZN on April 1, 2006 Mail this to a friend!

Good Article.

For those who think good grounding is a waste of time... You are either simply trying to create controversy due to some personal psychological issue or you DON'T understand it technically. It one or the other. Period. There is no in between.

Every commercial communications system, computer center, flammable tank farm, electric utility system, chip and computer manufacturing facility, commercial broadcast station, telephone facility and about any other kind of similiar operation has supurb grounding... BECAUSE IT WORKS.

Lightning protection, or LACK thereof, is simply a matter of how much RISK you CHOOSE to take. It is a simple statistical numbers game.

73, K0ZN
 
Lightning and Grounding  
by WA1RNE on April 2, 2006 Mail this to a friend!
On the installation of ground rods, here's a couple of neat ways to do it besides the back-breaking sledge hammer method:



This one is from Erico, the Eritech Ground Rod Driver:


http://www.erico.com/public/library/fep/rod-drver.pdf


** Note: You could probably homebrew a similar tool using a piece of boiler tubing as the outer body and a piece steel rod or thick wall tubing as a driver.



This is an interesting approach by K8RI that uses a water drill:

http://www.rogerhalstead.com/ham_files/ground.htm


73, Chris
 
RE: Lightning and Grounding  
by K8MHZ on April 2, 2006 Mail this to a friend!
Here is something I would like to attempt to clarify.

Fact: Air is an electrical insulator

Myth: Lightning travels through tens of thousands of feet of air.

Confusing? What happens when lightning strikes is a partial equalization of potential between the clouds and (for the purpose of this article) the ground. This difference in potential is huge. So large, in fact, that it changes the air to a mixture of electrically conductive ions that have both the characteristics of a conductor and a resistor. The ions conduct the electrons to ground but are resistive enough to create an enormous amount of heat.

Glass is an insulator. An eighth of an inch of glass will insulate far more voltage than the insulation of the feedlines we see people placing in glass jars. In the case of a direct hit, a jar is of little consequence because the voltages will be such that the insulation of the feedline will be invisible and most likely arc out of the line before it gets to the jar. But for transient voltages that the insulation can handle, the jar is a perfect insulator. But the current induced has to form a circuit somehow. The path it takes may not be through the glass, but it will find a path back to it's source. The glass may help to keep that path out of the shack under some circumstances.

If we create a means to dissipate the ions to the earth we also are reducing the likelihood of a path to ground at that point due to the reduction of ionization that may occur there. That is why grounding can be effective with conductors that will fuse open under a direct hit. Grounding, even of a low current path nature, is a form of prevention as well as protection.

With some effort, direct hits can be controlled. The systems require constant maintenance an measurement as they are dependent on the integrity of the connectors and materials the system is constructed of.

The NWS has many radar installations that operate while taking direct hits. Those installations have a need to operate under those conditions.

There are few amateur stations that have such a need. For the rest, the very best protection is to slide the feedlines through their prospective holes and ground them outside the shack. Next, unplug the radios and power supplies and move the plugs a foot or so from the receptacles.

Don't trust the strip suppressors unless they are of a tested brand, like TrippLite, AND are accompanied by a whole house surge arrestor mounted on the main service panel. An explanation of why can be found on the NFPA website. A better explanation is the fact that I personally know of someone that lost a quarter of a million dollar log home to a fire created by an electrical surge. You may also find it surprising to know that the strip suppressors can create fires when subject to long duration transients.

An true arrestor STOPS or arrests the surges at the panel while a suppressor only reduces or suppresses them by changing the excess voltage to heat and can only do that for short periods of time, and are limited to lower and upper limits by design. Sometimes the lower limits aren't low enough and will allow for some equipment to be damaged, and the upper limits are too low to work while taking a direct hit.

If you don't build lightning protection systems for a living and have witnessed Mother Nature's test of your work, and it has held forth, any attempt at creating a lightning proof shack while metal conductors come from outdoors, probably elevated, into the shack and are connected to equipment there is just a gamble.

For personal safety we could have a remote transmitter controlled by fiber from a safe shack, but we would still chance the remote station's destruction. Better just that, though.

From what I hear, there are some storms coming our way. My stuff will be disconnected.

I am also putting together a grounding bar for my coax. This will be such that the 259 connectors will screw into it and solidly and effectively ground both the center conductor and the shield. (Don't forget to ground BOTH for storm protection)

Stay safe and 73,

Mark K8MHZ





 
RE: Lightning and Grounding  
by K8MHZ on April 2, 2006 Mail this to a friend!
For putting in ground rods (I have done many!!)

Go to your local Tractor Supply and spend 20 bucks on a 'T-post driver'. They even have a deluxe model with a moving weight in it for about 30 bucks.

Your back will love you for it!

For ground rods over 10 feet long you need threaded rods (about 15 bucks apiece) and couplings (about 4 bucks apiece). If you can't get a lead rod with a point, make sure you use a grinder and make a point on the lead rod. It will help, trust me.

If you really want to be sure of good surface contact, there are compounds to treat the rod with. Scotch Brite is used to remove the oxidation. Next the compound is placed on the clean rod and then it is driven in. We don't get that elaborate. Check out sites that specialize in lightning protection and the stuff is available there.

If you are using ground clamps, it is important to re-tighten the clamps as the LAST STEP before burying them. They usually come loose by even the few last taps with a hammer driving them in. Don't over tighten them, the do crack rather easily if you get too Gung Ho. Putting No-Ox on the connectors is also prudent.

What to do with your left over lawn fertilizer? Fertilize your ground system with it. When it rains the ionic compounds in the fertilzer will make for a less resitive path to ground from your ground rods. The downside is that any hydrated polar ionic compounds are corrosive to metal, making it more important to protect the rods and connections if you decide to use treated earth.

There are two hobbies that should be done in thunderstorms with equal caution. Golf and Amateur Radio.

73,

Mark K8MHZ
 
RE: Lightning and Grounding  
by KB9CRY on April 2, 2006 Mail this to a friend!
I'm not going to stop:

A poster wrote in part:
"Turned the lights off and noted sparks jumping the PL 259! Never did get violent, but still a reminder what goes on IF you do not unplug things."

No this is just a reminder of the induced energy (I'm assuming there wasn't a direct strike.) your system can experience and is an example of a not properly designed and installed lightning/grounding system.

Mark wrote in part:
"An true arrestor STOPS or arrests the surges at the panel..."

I'd rather you say that a true arrestor shunts that energy to ground where it really wants to go. I doesn't really stop it, it just redirects it to ground before it gets to ground via your equipment. Induced energy/lightning wants to go to ground, in the worst way. The quicker and more direct path you can direct it the better for you. It's really quite simple if you do some homework and reflection. And, these devices, the good ones, do really work, as Mark has also pointed out.

No emotions needed folks. Quite simpe physics. You're just helping Mother Nature out by providing a very direct path to ground that's not through your equipment.

Phil KB9CRY
 
RE: Lightning and Grounding  
by KB9CRY on April 2, 2006 Mail this to a friend!
I heartily disagree with Mark's comments:
"If you are using ground clamps, it is important to re-tighten the clamps as the LAST STEP before burying them. They usually come loose by even the few last taps with a hammer driving them in. Don't over tighten them, the do crack rather easily if you get too Gung Ho. Putting No-Ox on the connectors is also prudent."


Never never use ground clamps for buried connections. They will loosen up due to the normal thermal cycling between night and day and the seasons within about a month. Trust me, I've had some experience.

For any kind of of underground grounding connection, the only, maintenance free, reliable way to go is to use exothermic welds. Soldering of any type is not acceptable since the solder will melt with any kind of surge current.

Also, Cadwelds and the other similar types, are actually quite safe to use, contrary to one previous poster. The OneShots have everything you need and work like a champ. (Always buy one more than you need since you'll have a short learning curve.)

PHil
 
RE: Lightning and Grounding  
by K8MHZ on April 3, 2006 Mail this to a friend!
Hi Phil,

While I do appreciate your view on CadWeld, and do agree with you that they are FAR superior to clamps, the fact remains that the vast majority of hams will still use the clamps. My instructions were aimed at making the use of the clamps as best they could be. If you are seeing clamps coming loose in a month either there is some very harsh cycling there or the clamps were inferior and improperly installed. I have had much better luck with them. Were the clamps that were coming loose rated for underground use and properly installed?

What we don't agree on is how 'safe' CadWelds are to use. I see electricians get burned by lighting them on occasion. I have seen them explode. Usually what happens is the two separate powders get mixed up and won't light until it gets hot enough to go all at once. Moisture is a problem too. Fortunately, a ham buying a box of One-Shots to take home and use right away will get a better product than one that has been bouncing around on a service truck for a couple of years.

I would recommend that anyone using CadWeld for the first time try to locate someone that uses them regularly to help. Especially if you find that it won't light like the instructions say. Be careful, I have seen some pretty impressive pyro from guys lighting off CadWeld, they will strip you of your eyebrows in a....flash!

The surge arrestors DO arrest at the panel by shutting off the main breaker in just a few milliseconds. I don't have the specs in front of me, but ones we use are pretty fast. Their speed does depend on the function of the main breaker. Some breakers are instantaneous trip while others are inverse-time. The fast trips are desirable for use with a whole house surge arrestor. Google will give more technical details on both the arrestors and the characteristics of different breakers. I have found, for instance, that Square D breakers are very fast, Cutler Hammers are very slow. I once saw a 15 amp Cutler Hammer breaker carry 115.7 amperes for 3 seconds before I shut it off. Scary. Stay with Square D.

Thanks for your input, perhaps with your insistence of using CadWeld and my warnings of safety, we may have provided for some better amateur radio installations down the road.

73,

Mark K8MHZ



 
RE: Lightning and Grounding  
by KG6WLS on April 3, 2006 Mail this to a friend!
--Thanks for your input, perhaps with your insistence of using CadWeld and my warnings of safety, we may have provided for some better amateur radio installations down the road.

73,

Mark K8MHZ--

Amen to that Mark! And, stay away from those Zinsco's. I sleep better knowing that I installed or serviced Square D equipment. However, just got done installing four Cutler Hammer 12kv switches (with the heaters to keep the moisture out) over the weekend. They should last longer than the last ones... being that the gear was over 30 years old and not rated for outdoor use to begin with :(

Well, gotta get back to work and do some hi-pot testing.

Be safe and 73!
Mike
 
RE: Lightning and Grounding  
by KC8VWM on April 3, 2006 Mail this to a friend!
Mark,

Since your an electrician by trade, I was wondering if you could provide us with a little insight on electrical code and how hams are grounding thier stations.

Any Pro's / Con's / things to look out for that stick out in your mind when installing an antenna system / shack grounding system?

Also is braided strap or solid copper a better choice for antenna / shack grounding installations?

Thanks in advance for your expertise on this matter.

Charles - KC8VWM
 
RE: Lightning and Grounding  
by K4RAF on April 3, 2006 Mail this to a friend!
The reason why cell sites are the least damaged is an overall standard applied to all sites.

Everything that is metal is bonded to the ground ring that encircles the compound. Items included in the bonding include: shelter door frames (or outdoor equipment cabinets), coaxial entry ports, fence posts, fence gates, generator frame, boom gates (to tower), top & bottom coax (just below connectors) & anything metal like vents: PERIOD. Inside the shelters, there is a omnidirectional halo that grounds everything inside the shelter. Any subsequent shelters (for colocations in same compund) are bonded diectly to the existing ring. I have visited compounds with as many as 25 seperate shelters but everyone of them is at the same ground potential.

It is believed that by doing this, it drains away the voltage buildup on the structure, thus reducing any voltages induced.

After visiting well over 1000 sites, from rooftops, to water tanks, to 1800' towers, I have never seen any destroyed equipment or antennas. However, I have seen blown surge suppressors on T-1 phonelines & electrical ingresses.

For those who have poor soil conductivity, a company called Lyncole XIT Grounding that sells "chemical ground rods". These rods are treated with salts that bond to the ground (salts within the rod) to lower resistance. These salts are a less caustic formula of Epsom salts, which can be used to increase ground conductivity.

 
RE: Lightning and Grounding  
by KG6WLS on April 3, 2006 Mail this to a friend!
Charles,

If you scroll back up a few day, I posted a small section of the NEC pertaining to this.

73
Mike
 
RE: Lightning and Grounding  
by KG6WLS on April 3, 2006 Mail this to a friend!
March 31st. to be exact. :)
 
RE: Lightning and Grounding  
by K8MHZ on April 3, 2006 Mail this to a friend!
"Well, gotta get back to work and do some hi-pot testing."


I hope you have some big strong apprentices to carry the machine for you! The one I used when I did iso-phase testing for Egezii weighed 83 pounds.

83 lbs and put out 85kV.

I know what you're going through dude, take your time and stay safe! Take extra care on high voltage DC cables. E-mail me for a story about 'em.

73,

Mark K8MHZ

k8mhz@k8mhz.com
 
RE: Lightning and Grounding  
by K8MHZ on April 3, 2006 Mail this to a friend!
Hi Charles,

I see you survived your beating ;)

What I see most is first, a lack of safety grounding followed by failure to bond the shack system to the mains as required.

One problem we, as hams, will find when we bond our systems to the water pipes is that sometimes the pipes will act as radiators and actually induce RF into the building. This is especially true where the distance between connections is long. Sometimes, in order to both comply with code and reduce RF it is necessary to have several rods all bonded together outside the shack. As mentioned in the post about cell towers, 'rings' are used both to sustain a good equipotential plane and to provide very short paths to an effective ground. Ground rings work very well for this purpose and also have other advantages.

We all need to realize that most of us for whatever reason won't be able to install the perfect system even if the technology exists. As such we need to try to do the best we can within our limitations and depend more on disconnection than engineering.

As for antenna systems the biggest failure to meet code is wire size. Nothing under #14 is allowed for wire antennas. This is not a grounding issue but is present for other reasons.

As far as braided strap vs. solid copper wire we need to consider several factors. First, I use braided strap, made from coax shields, inside the shack only and only as long as it remains oxidation free. You can purchase tinned braided strap which is less prone to oxidation induced impedance but I would hesitate to use it underground. As far as a comparison otherwise, a wide strap is better than a small solid wire, and a large solid wire is better than a small braided strap. For underground applications solid wire is better as it oxidizes in a different manner. Solid copper strap (strip) is even better but the issue now becomes making the connections. If you go to the extent of using solid strap, locating a die for using CadWeld or some other form of exothermic welding should be used lest your extra efforts be fruitless.

I applaud Phil for focusing our attention to the grounding electrode connections. His approach is merited, but unfortunately idealistic. A realistic approach is to realize that most hams will choose to seek a compromise and my efforts are to guide them to the most idealistic reality they can achieve given their limitations.

The limitations I speak of may be financial or they may just be that their landlord may not like them digging up the terrace and doing exo-thermic welding on the premises. They may be physically unable to perform the work.

Our grounding systems, due to such limitations and changes thereof, will probably undergo constant upgrading. If all we can do is to use clamps at this time, using the proper ones and installing them correctly will make them much more effective.

If they realize that although a wide braided strap is great while it is new but useless when oxidized, they may just take the additional effort to use solid wire where they can.

Another limitation is availability. I would love to be able to go to my local electrical supply house and get some #2 Solid Bare Tinned Copper wire but they don't carry it. Some hams may live 100 or more miles from anyone that carries CadWeld or similar products.

A comparison of available products and their good and bad points is great information for the masses and should make for some better installs. Perhaps even a few really great ones.

73 my good man,

Mark K8MHZ
 
RE: Lightning and Grounding  
by K8MHZ on April 3, 2006 Mail this to a friend!
Here is an interesting story that illustrates how ineffective some grounding systems can be.

I was recently involved in a complaint that a local ham had made about an insurance office that had a telephone system that was interferring with most of the 75 meter phone band. The FCC had sent a field agent out and she verified that owner of the office was violating FCC rules and had to either remove his telephone system or make it comply with FCC rules.

My investigation supported both the FCC's findings and that of the amateur, the telephone system was the generator of the interference. What I found that the others missed was that the GROUNDING system was the radiator! The metal frame of the shower door in the bathroom was pinning my signal strength meter. We went outside and found that the single ground rod installed for the electrical service was also radiating the signal just as if it was hanging free in the air.

I passed on my findings to the vendor that installed the phone and the owner of the insurance company. I also suggested that an outside electrical contractor come in and install at least a two rod system as I did not want to appear to have a conflict of interest in the case.

I was later informed that the grounding system was changed and now the filters installed by the vendor were working. They had little effect on the problem while the building was not effectively grounded. The area is almost on a sand dune and most of the soil is trucked in topsoil placed on white dune sand.

BTW, the insurance guy actually got a call on the phone from Riley Hollingsworth. Once I heard that I knew that the FCC was not just going to ignore the amateur's compliants.

I told the owner of the building that once the grounding was proper just keeping friends with the neighbor wasn't the only benefit. He now has a safer AC electrical system.

73,

Mark K8MHZ
 
RE: Lightning and Grounding  
by KC8VWM on April 3, 2006 Mail this to a friend!
Excellent and most constructive thoughts.

My setup sounds similar to your own. I use braided straps indoors which connects all my equipment to a common grounding bar in the shack.

I have installed 2 copper ground rods outside for my radio equipment.

The first one is connected directly to the shack grounding bar using # 4 solid copper wire. I have run it directly to a ground rod located just outside the window to my shack.

The second ground rod is connected directly to the antenna on the roof.

There are all bonded together with the main electrical service ground using one "continuous" run of # 4 solid copper wire which happens to be buried between all the ground rods.

I have clamped the solid wire to the ground rods and then sprayed automotive "battery terminal" spray to further protect the connections from oxidation and corrosion.

To achieve maximum soil conductivity, I decided that water softener salt pellets were relatively inexpensive. So I spread a bag of them around the groundrods. I was careful not to disolve them directly over the ground rods or thier connections.
The pellets are easily dissolved using a garden hose, or you can let mother nature do it for you.

One thing to note is that salt quickly kills grass. However, if you spread fresh topsoil on top of the area shortly after you dissolved the salt pellets, then plant grass seeds there, it will grow back very quickly.

The electrical service ground connection in which both ground rods are bonded is located under my deck in proximity of my electrical service meter.

Not only does spreading a little extra salt pellets around the soil under the deck creates a nice bed of conductive soil, but it also helps keep the vegetation from growing under the deck, which I suppose could be considered as an added benefit.


73

Charles - KC8VWM
 
RE: Lightning and Grounding  
by KC8VWM on April 3, 2006 Mail this to a friend!
One observation I quickly noticed is that before my grounding system was installed, I had a constant S-7 noise level when listening to HF bands.

After the ground rods and salt treatment, I only seem to detect noise during atmospheric distubances. Otherwise, I sometimes find myself tapping the signal meter to make sure it still works. :)

73 Charles - KC8VWM
 
RE: Lightning and Grounding  
by K9KJM on April 3, 2006 Mail this to a friend!
Many many good comments filed here! Great post. A few items I have not seen much reference to include the use of plain old copper tubing. Tubing provides lots of surface area and is cheaper to buy than solid wire.
Again, The desired flat copper strap can be obtained in most areas from upscale roofers. (They USED to just toss scraps in the dumpster! But now with scrap copper prices up they may no longer do that!)
Most hams do not have the ability to use exothermic (Cadweld) to bond conductors together.
True silver solder (NOT the stuff sold in home stores for plumbing) works great instead of Cadweld. One of its trade names is "Silfoss" Comes in straight sticks about 16 inches long (One stick will do quite a few joints) Available at most any welding supply store. This is the stuff used to repair air conditioner units. MAPP gas in a small hand held torch will flow it just fine. Do NOT use lead/tin solder outdoors, As already mentioned! (Turns to white powder in a few years!)
 
RE: Lightning and Grounding  
by KB9CRY on April 4, 2006 Mail this to a friend!
A poster wrote:
"Most hams do not have the ability to use exothermic (Cadweld) to bond conductors together."

This is wrong. If you can learn CW and climb a tower, you can do CadWelds. Erico's OneShots are quite easy to use, safe to use if you follow directions, and work like a champ. Do not be confused folks nor dissuaded in these naysayers comments on your abilities. I have complete faith that most hams do indeed have the ability. The instructions that come with the OneShots are easy to read and follow. I wonder if these folks that make these comments have ever done a OneShot?!



True silver solder (NOT the stuff sold in home stores for plumbing) works great instead of Cadweld.


Wrong Wrong Wrong. Any kind of solder will quickly melt during any kind a high surge event. Go to the Polyphaser site and thoroughly read on their articles. Also NEC doesn not allow soldering of grounding connections. Ever wonder why?

Do not do it. Trust me. Use either exothermic connections or mechanical (clamps) connections. Period. Remember all this discussion about a properly designed and INSTALLED grounding system and remember all the stories about folks that have been bit by Mother Nature but then upon reflection they discover that they ignored, were confused, or didn't do well one tiny aspect of their system? Every single piece of the puzzle must be properly done to be effective.

Phil KB9CRY
 
RE: Lightning and Grounding  
by THERAGE on April 4, 2006 Mail this to a friend!
Good info. Kind of reminds me of the three lil' pigs:

"And I'll huff, and I'll puff, and I'll..."
 
RE: Lightning and Grounding  
by N6HBJ on April 4, 2006 Mail this to a friend!
"There is no lightning protection! If any typical ham antennas, transmission lines, remote tuners, and any other stuff hams use gets a direct hit, there will be nothing left, it will be vaporized except for a tower"


Years ago a friend's roof mounted tower took a direct lightning hit. It followed the path of the ground wire to ground. Blasted the paint off the side of the house but his equipment was unharmed.
 
#2 cable at surplus sales  
by KF6IIU on April 4, 2006 Mail this to a friend!
Suplus Sales has #2 stranded wire, jacketed. $2 - $1.50 per foot
 
RE: Lightning and Grounding  
by K4CMD on April 4, 2006 Mail this to a friend!
"Years ago a friend's roof mounted tower took a direct lightning hit. It followed the path of the ground wire to ground. Blasted the paint off the side of the house but his equipment was unharmed."

Five years ago a tree in my back yard, about 30 feet from my house, took a direct hit. I happened to be standing at a window that gave me a direct view of the strike and its path down the tree to ground. Unbeknownst to me at the time, my house's underground power line was about five feet from that tree. A lightning-induced surge came into the breaker box, jumped over to the service ground and paid a little visit to every outlet in the house that happened to have a three-pronged plug stuck in it. Three GFCI outlets were completely blown out of the walls they were mounted in. My $380 Sony home theatre receiver (which was turned off at the time) caught on fire. Up in the shack my Astron power supply took so hard a hit that it left a burn mark 3 inches in diameter on the table underneath it. The pulse continued through the power supply to the power cords of my Kenwood TS-570D and my Icom IC-2000H, which of course had been disconnected from their coax -- but no matter, they were fried. The pulse found its way BACK to ground by following the ground lead from my radios back outside! (I've got the burn marks on my ground wire's insulation to prove it.)

One $3,000 homeowner's claim later and now with a new insurance carrier, I'll tell ya ... the only way to stay absolutely safe is to disconnect EVERYTHING -- power cords included -- and let it all FLOAT. This is what my station does whenever it's not in use.

BTW, those of you who say a roof tower can survive a direct hit apparently are speaking only for the roof tower. A strike that close to home (literally), however, will take out stuff that's not even connected to the power line. A couple of years after that first strike, we had another one, this time to a tree in our front yard. This one didn't enter the house -- it just blasted three fist-sized holes in the ground around the base of the tree -- but the EMP from the strike was so great that it wiped out a battery-powered home weather station in an upstairs bedroom and two telephones on different floors of the house.

I'm with the guys who say all this grounding talk is great for near-misses. Believe me, even if your house survives a direct hit, you'll still be spending some bucks replacing stuff that got zapped by EMP. Been there, done that, wrote the check and had to change insurance companies!

73 and keep your head down!
 
RE: Lightning and Grounding  
by K8MHZ on April 4, 2006 Mail this to a friend!
Food for thought:

Look at the NEC closely pertaining to what type of feedline is allowed to pass through walls without the protection passing through an insulated bushing. Coax is allowed ONLY if effectively grounded.

K4CMD,

Bummer! That could have been worse, but wow, what a story.

Before I would make a recommendation that goes against all engineering and safety rules (let things float) I would question the integrity of your service main's grounding system. As I have personally witnessed, what LOOKS to be a good ground may not be one at all. With your history I would recommend that you get a resistance test done on your grounding electrode system. Tried and true is the fall of potential method.

It sounds like your QTH is very 'prominent', a word to describe locations that are likely to become paths for lightning. If so, your grounding requirements may be in excess of code minimum to be effective. The code does not require resistance measurements if two ground rods are used. That makes a very unsafe assumption that the two rods have contributed to a low impedance grounding system.

73,

Mark K8MHZ


 
RE: Lightning and Grounding  
by KC8VWM on April 4, 2006 Mail this to a friend!

Interesting article on grounding from a well known insurance carrier.

"The Importance of Proper Grounding."

http://www.statefarm.com/consumer/vhouse/articles/groundng.htm

 
RE: Lightning and Grounding  
by K8MHZ on April 4, 2006 Mail this to a friend!
A good source for suppressors and arresters:

http://www.aplussupply.com/intermatic/pg5000/ig1240.htm

I have to agree with Charles. The devices are dependent on a good grounding system according to the manufacturers.

73,

Mark K8MHZ
 
Lightning and Grounding  
by WU5E on April 4, 2006 Mail this to a friend!
Great Article, and good thread, good reading and good Behavior


73's de Jim
WU5E
 
RE: Lightning and Grounding  
by WA2JJH on April 4, 2006 Mail this to a friend!
Good artical. Yup a direct strike, your S.O.L.
I sold some extra TS-850 boards to a poor chap that showed me the photo's.

However something is better than nothing for a non direct hit.

Seems like the best protection is disconnecting the antenna from the rig.
 
RE: Lightning and Grounding  
by K9KJM on April 5, 2006 Mail this to a friend!
TO: KB9CRY Yes, "One Shots" do work well, And the average ham might be able to use them. BUT the price is HIGH!!!! Last I checked around 5 bucks PER JOINT.

The SILVER SOLDER I am refering to is the stuff STILL used to this day to install commercial AM radio station radials! You are clearly unfamiliar with what it really is! CHECK it OUT! NOT to be confused with "plumbing" silver solder at all! (Or plain lead / tin solder)
A single stick of REAL silver solder (Most of which has a content of around 15% REAL silver. (And is a STRONG mechanical as well as very low impedence electrical joint) will cost around 2 bucks and do at least 6 or so connections!

It is sad to see those very misinformed who think that "nothing" can protect from a direct lighting strike still hold on to the 1950s old wives tales and stories of damage of properly unprotected stations being damaged.
They clearly did NOT read all the posts of how to properly protect a station.
Here is the best site I have found to see the real facts: http://members.cox.net/pc-usa/station/ground0.htm

 
RE: Lightning and Grounding  
by KC8VWM on April 5, 2006 Mail this to a friend!
Seems like the best protection is disconnecting the antenna from the rig.

-----

Imagine the poor sap that ends up going through all the trouble of doing just that, only to find out later that lighting damaged his radio because his radio was connected to an AC line with a poor utility ground connection outside?

 
RE: Lightning and Grounding  
by K8MHZ on April 5, 2006 Mail this to a friend!
http://members.cox.net/pc-usa/station/ground0.htm

Yes, this is a great site!

I just got off the phone trying to locate large diameter solid copper wire. I called the two electrical suppliers in the area, All-Phase and Fitzpatrick Electric. Neither has anything larger than #6 solid. The counter person at Fitz's actually started to get indignant when he tried to tell me that I did not need solid wire for lightning protection and tried to sell me stranded wire. He said he 'wouldn't get into the technical aspects as to why stranded is better'. Once he realized that I wasn't interested in purchasing wire that I already had on the truck he gave me some prices for order only. All-Phase didn't try to talk me out of my request but also only has #4 and larger copper by special order only.

I then remembered that a company I used to work for is now building cell towers. One phone call and I found the Holy Grail of ground field bonding, #2 SBTC, in stock and at a price that beat the suppliers all to heck.

So, if you want material for use in lightning protection and your suppliers don't carry it due to their presumed expertise or whatever, call an electrical contractor that designs and builds ground fields for the wireless communications industry and make friends with the person in the stock yard. They will usually sell for the same price they purchased the stuff for if you tell them it is for personal safety. They may also be a good source for threaded ground rods and couplers which are getting pricey.

As for the silver solder, the special stuff, I would like to learn more about it before I make an evaluation. The NEC does not like solder alone and prohibits it's use in place of a weld or a mechanical connection. This may be considered more of a braze, I would like to learn more about it.

73,

Mark K8MHZ
 
RE: Lightning and Grounding  
by KB9CRY on April 5, 2006 Mail this to a friend!
Congrats on finding that solid wire. One may have to be resourceful and persistant, but in the end you'll be better off by "doing it the right way" than cobbling together perceived alternates.

Which leads me to the other topic, that of is soldering (using silver or whatever) versus exothermic or mechanical joints.

I'm not about to and do not want to get into a match with KJM but my learnings and understanding of NEC is that no kind of solder, regardless of the silver content, is allowed for ground rod connections. Period. If others have a better understanding of the regulations then please enlighten us. But doesn't it make sense that a joint that is formed by melting something would be deficient if a sufficient amount of current is applied to that in a high energy surge? That energy would be converted to heat and might that joint then tend to melt?

And folks, let's not complain about a CadWeld OneShot costing $5-7 per joint and doing it the really right way versus trying to save a few bucks by using something that is not allowed like solder.

Again, if soldered joints is allowed by code, please inform me and steer me to the reg.

Now is not the time to save a few bucks, that's the entire purpose of the properly designed and installed grounding system, is to save a lot of bucks by preventing damage to your equipment.

Phil KB9CRY
 
RE: Lightning and Grounding  
by KC8VWM on April 5, 2006 Mail this to a friend!
Again, if soldered joints is allowed by code, please inform me and steer me to the reg.

-----------
Ok, here's a few cut and paste sections for consideration::

"Where a lightning protection system is installed, it must be bonded to the building or structure grounding electrode system as per 250.106."

"Ground rod. It must have at least 8 ft of contact lengthwise with the soil (which means, of course, it can't be less than 8 ft long) [250.53(G)]"

"The upper end of the ground rod must be at grade (or underground) unless you protect the grounding electrode conductor attachment against physical damage per 250.10. See 250.52(A)(5) and 250.53(A) for details."

"Listed ground rods must be at least 1/2 in. diameter. The diameter doesn't affect resistance to ground (earth)-see IEEE-142, Table 13 for reference. Larger diameters increase mechanical strength (and service in the face of corrosion."

"Bonding" means that are permitted include bonding type locknuts and bushings. Also included are threaded couplings and bosses, threadless couplings and connectors, and using the grounded service conductor with exothermic welding, listed pressure connectors, listed clamps, or other listed means as permitted in Section 250-8."

73
 
RE: Lightning and Grounding  
by K2WH on April 5, 2006 Mail this to a friend!
You don't need no stinkin ground protection. If you get hit, you get hit. Besides, its not like the lightning is looking only at your antenna. An antenna getting hit by lightning is just stupid luck.

A bolt of lightning is looking at a very large goegraphical area not just that little stupid aluminum thing you got sticking up in the air.

K2WH (No grounding ever, no lightning ever, no problem ever)
 
RE: Lightning and Grounding  
by KC8VWM on April 5, 2006 Mail this to a friend!
K2WH (No grounding ever, no lightning ever, no problem ever)

------

KABOOOOOOOOM!!!

:)
 
RE: Lightning and Grounding  
by KG6WLS on April 5, 2006 Mail this to a friend!
K2WH (No grounding ever, no lightning ever, no problem ever)

Russian Roulette = "People can and do survive direct lightning strikes, but they're the exceptions; most strikes are lethal. Not taking precautions in this situation would be like Russian roulette -- only more likely to kill you."

73
From somewhat sunny Southern CA. :)
 
RE: Lightning and Grounding  
by K9KJM on April 5, 2006 Mail this to a friend!
I may be misleading in calling the product I am refering to "Silver Solder" The process is actually much more akin to brazing (Or welding) As the copper is actually brought up to a dull red color to get the Silfoss to flow. "Silver Solder" is what we called it in the old days of AM tower construction. It is NOT like regular solder at all.
Think brazing rod with a very high silver/copper/nickel content.
The connection joint when finished actually has more mechanical strength than the original material.
 
Lightning and Grounding  
by BHARDIMON on April 5, 2006 Mail this to a friend!
Don't knock grounding. It gives hours of pleasure for anal retentive hams.
 
RE: Lightning and Grounding  
by KB9CRY on April 6, 2006 Mail this to a friend!
I believe I understand what KJM is talking about relative to the brazing material but as VWM has listed, there is no specific listing for that type of bonding in the codes. So, if it's not specifically listed then you'd be technically in violation of the current codes, which may have been different or not followed back in the old days of AM.

I'm just trying to point out that we ought to do the proper educational service and only list what is the presently "approved" methods of joining ground connections even if we personally have other knowledge of other types of joining methods that may work.

As has been pointed out, it may be misleading to say "silver solder" is OK.

We all need to educate ourselves and there are many very good technical articles that describe in detail what to do and what not to do, if you so choose to accept the mission.

Phil
 
RE: Lightning and Grounding  
by KD8DBL on April 6, 2006 Mail this to a friend!
I've been following this thread for the past week - lot's of good info. I'm a brand new Ham (got my General ticket on 3/20) and I'm in the middle of setting up my shack. Grounding became a hot topic with me a couple of weeks ago and started researching the net. I read alot of the info on the Polyphaser site as well as some of the links mentioned here. One article I read was a QST article called "Lightning Protection for the Amatuer Station" by Ron Block. It explains grounds and lightning protection as good as most and depicts a methodology for indentifying all the I/O needing protection in the shack.

Couple of questions for those who might have answers. For the perimeter ground around my house, I was thinking of using copper strap as ground rod interconnection. I looked through the Cadweld info and didn't see anything obvious as a product to bond copper strap to a ground rod. I saw something mention here - does anyone know if it is possible to exothermically bond copper strap to ground rods? Does copper strap seem like overkill, as a lot of you speak of using #2 solid copper wire?

Is there also a min/max distance that I should place my perimeter ground system around my house. I'll have access to a little more than 75% of the perimeter - most of it right next to the foundation.

I only have a moderate background in electronics, but certainly agree that this proctection is a must and that practicing some of the myths listed here or relying on luck is just a disaster waiting to happen.

Dave
 
RE: Lightning and Grounding  
by KC8VWM on April 6, 2006 Mail this to a friend!
KD8DBL asks,

Q. For the perimeter ground around my house, I was thinking of using copper strap as ground rod interconnection.

A. It's not that you can't use copper strap, it's just that you want to choose an appropriate conductor that is not prone to accelerated corrosion when exposed to the outdoor environment.

Q. Does anyone know if it is possible to exothermically bond copper strap to ground rods?

A. Yes it is possible however there may be no long term benefit because small air pockets would be trapped between the open porous strap and the grounding rod conductor. Trapping air between the connection defeats the purpose of exothermic bonding for improving the connections overall strength.


Q. Does copper strap seem like overkill, as a lot of you speak of using #2 solid copper wire?

A. Copper strap is in fact superior to # 2 wire. However there are many other things to consider in the equation such as corrosion resistance. Copper strap tends to trap moisture between it's own weave. Solid copper wire on the other hand oxidizes on the outer surface area however it does not trap moisture inside and this does not affect it's overall conductive properties.

Q. Is there also a min/max distance that I should place my perimeter ground system around my house.

A. The rule of thumb for any grounding system is that you keep all ground conductors as short and as direct as possible. It is not necessary to build a "perimeter" grounding system around your entire home. It is however required that you bond all ground rod connections together. Solid copper wire can be buried between ground rods.

73 Charles - KC8VWM
 
RE: Lightning and Grounding  
by K2WH on April 6, 2006 Mail this to a friend!
Remember, gounding does not prevent lightning strikes and some think it even attracts lightning by lowering the resistance between ground and cloud.

The grounding of an antenna system is for the purpose of dissipating all the power of an actual strike, safely with either minimal or no damage to equipment into the earth.

A single ground rod is insufficient to handle the huge current surge in a direct strike. Multiple ground rods must be driven and situated in such a way as to provide a nearly ZERO impedance to ground. This is something the average ham cannot do or even measure correctly.

Sure there are many how to books on the subject and well meaning hams to provide instruction on the subject, but all this effort is for naught.

Therefore, going nuts about lightning protection is usually a waste of time and money since the average ham will not do it correctly or can't do it correctly and if his antenna(s) are hit, it will just vaporize and destroy everything anyway as if the grounding was never installed. So, why bother, have at it.

K2WH
 
RE: Lightning and Grounding  
by KC8VWM on April 6, 2006 Mail this to a friend!
Remember, grounding does not prevent lightning strikes and some think it even attracts lightning by lowering the resistance between ground and cloud.

-----

Bill, with all due respect there is a great deal of scientific data to support the idea that grounding your station antenna will protect your radio equipment from lightning damage during a lightning storm.

The way grounding works on your antenna sytem is that it "camouflages" your antenna from lighting because your antenna becomes subjected to the same electrical potential as the ground itself.

Therefore this means that your antenna is less likely to become a "lightning rod" when the ground is just as easy a strike for the lighting to "seek out" as the antenna itself.

Grounding your antenna means you have "equalized" the ground potential between the earth and the antenna. They are now both an equal and level playing field for lightning strikes.

However, when your antenna is NOT grounded, then your antenna behaves more like a "lightning rod" which actually serves to attract lighting to it.

"Camouflaging" your antenna from lightning doesn't eliminate the risk completely, but just like hunting behind a duck blind, it improves your chances.

73 Charles - KC8VWM
 
RE: Lightning and Grounding  
by KG6WLS on April 6, 2006 Mail this to a friend!
This has been quite an interesting topic for the past several days. Some pros, and some cons. But, informative all the same...however you look at it. I guess you can lead a horse to water, but you can't make it drink. Oh, well.

More info here to absorb:

http://www.arrl.org/tis/info/pdf/0206056.pdf

http://www.arrl.org/tis/info/pdf/0207048.pdf

http://www.arrl.org/tis/info/pdf/0208053.pdf

73
From sunny Southern CA.

 
RE: Lightning and Grounding  
by K2WH on April 6, 2006 Mail this to a friend!
"Bill, with all due respect there is a great deal of scientific data to support the idea that grounding your station antenna will protect your radio equipment from lightning damage during a lightning storm."

I agree. However, my posting states, that most hams, probably 99% do not do it properly or put to little effort into it. No sense fixing your car if its going to be hit by a truck.

Most damage to equipment does not result from a direct hit. It is from induced voltages in wires, conduit and other conducting metal objects from a nearby strike. These induced voltages attempt to find ground any way they can and if it goes through your equipment your are toast.

While I agree, grounding antennas, towers etc is a good idea and should be done if practicle, I look at it differently. I have had antennas for 37 years and nary a strike, near strike or loss of any equipment (even the phone or cable TV) due to lightning. I have 75' verticals (ungrounded), 80 foot high dipoles (no spark gaps), Satellite antennas (ungrounded) etc.

While I may be lucky, I can't help but think of the tens of thousands of trees in the 50,000 acre forest I live and rarely do they get hit. I think of all the power poles with all those wires up there that I have never seen get hit. I lose power from cars running into power poles or trees toppling over much more than lighting hitting wires or anything else.

So, I believe the odds are in my favor. Sort of like playing the lottery I guess - you never win. If I get hit this summer season, I'll let you know (if the computer still works).

K2WH

K2WH
 
RE: Lightning and Grounding  
by KD8DBL on April 7, 2006 Mail this to a friend!
Thanks for the feedback Charles. Interesting info on the moisture problems with copper strap. It seems that #2 wire would be easier to install, although the RF impedance would be a little higher.

I did read in a couple of other articles that putting a perimeter around the house is the way to go. My power, cable and telco services are on the opposite side of the house from my shack - so by default I will be making a perimiter anyway.

Again, thanks for the info.

Dave
 
RE: Lightning and Grounding  
by KB9CRY on April 7, 2006 Mail this to a friend!
I trust that everyone will look past the couple of recent posts by one individual who is poo-pooing the idea of grounding (he seems to be the luckiest person on earth) and who has no faith in your abilities to follow instructions and do everything as directed down to the minute detail. It's not that hard and really not that involved.

Properly designed and installed grounding systems really do work, can survice a direct strike, and can protect your equipment. Don't be dissuaded by these naysayers. Do your homework. Listen to the experienced folks. Do it the right way. Phil
 
RE: Lightning and Grounding  
by K2WH on April 8, 2006 Mail this to a friend!
Hey Phil. You have no idea what YOU are talking about. I test and certify lightning protection systems for commercial tower owners.

They are the ones who need the protection, not the average ham with a Butternut in his back yard or a dipole strung between (2) trees. The way people are carrying on here one would think there is an epedemic of lightning related deaths in the ham community.

The commercial installations are usually very high and large and able to take a direct strike and handle it with no problem including side strikes due to proper grond rod distribution and ground mats.

I'll say it again, installing lightning protection is a good thing, but a direct hit on the average hams antenna installation is just as good as no installation since grounding methods used cannot absorb or prevent secondary strikes due to the ground potential levels.

More hams are killed or receive equipment damage putting up antennas and contacting overhead power lines or falling out of trees. Give me a break.

K2WH
 
RE: Lightning and Grounding  
by THERAGE on April 8, 2006 Mail this to a friend!
Zzzzzzzzz.
 
RE: Lightning and Grounding  
by K8MHZ on April 8, 2006 Mail this to a friend!
K2WH

"I test and certify lightning protection systems for commercial tower owners."

May I ask for what company?

"but a direct hit on the average hams antenna installation is just as good as no installation since grounding methods used cannot absorb or prevent secondary strikes due to the ground potential levels."

I have to admit I am a bit confused by this statement. Are you referring to Ground Potential Rise (GPR)? We are taught that GPR can damage equipment connected to a remote ground (Telco, CATV). Amateur equipment should be single point grounded locally. When reference is made to 'direct hits' I don't think people are talking about their buildings, it is their antennas. I think most would be satisfied to have a system that would allow their antenna to be hit, possibly destroyed, and shunt the strike at the antenna to ground and keep it out of the shack.

To that effect I feel that proper bonding to attempt an equipotential plane and a good dissipation system between the antenna and the shack can be done with some effort. If you are 'in the business' you may be able to enlighten us on grounding pads, multiple rod systems, electrolytics, capacitive spiders and how we can home brew some of these to try at our shacks. Further discussion on the types of conductors that won't fuse open on a secondary strike....or better yet why not explain why we are more concerned with secondary strikes than primary strikes?

Thanks much and 73,

Mark K8MHZ


 
Lightning and Grounding  
by CAMPCOHEN on April 9, 2006 Mail this to a friend!
I'm a new member, and wanted to say a few words to support Mr. Higgins' post. In particular, he has emphasized the use of copper strip as a grounding conductor, and has at least mentioned the importance of bonding, the interconnection of different parts of the grounding system. These issues are rarely brought out at the "amateur" level. The bonding is absolutely critical to building an effective protection system.

I have been in the lightning/surge protection field for 20 years, first as a scientist/manager at Bell Labs, then at Panamax, and now as a consultant, registered with the IEEE Consultant's group.(My CV is posted in that web site.)

From my first contact with lightning protection iissues, I was amazed at the impact of the "charlatan factor"- the presence of people and businesses in the field based on pseudo-scientific, unfounded ideas and claims. Their businesses succeeded by dint of strong salesmanship, testimonials from ignorant customers, cronies, and brothers-in law, and lawsuits (supported by the profits from the sale of the ineffective equipment) to suppress engineers and scientists who tried to remedy the situation.

The controversies, and misinformation generated to increase the sales of specific products, have created lots of confusion about the science and technology of lightning and protection. Whereas the real technical experts had a detailed and well-understood picture about these issues, the non-specialist population had a very confused and inadequate knowledge base.

A few years ago I and four other experts tried to improve this situation by writing a short book about lightning and lightning protection, intended from the beginning for web publication by the IEEE, to get broad distribution, to improve the state of knowledge of these issues. That is now available as "How to Protect Your Home and Its Contents from Lightning". It is a ~1MB pdf file that can be downloaded from: www.Panamax.com (go into Consumer Zone, then Knowledge Center) or from www.omegaps.com.

While it emphasizes the residential environment, much of the introductory discussion will be useful to forum members as the basis for planning improved systems for their rigs. A number of common errors are also shown.

The "Guide" represents a consensus of five individuals, all members of the IEEE surge protection experts group, employed variously by three manufacturers, EPRI, and Duke Energy. There was very little difference of opinion among these people about what the problems were, and how to solve them. The "Guide" does not push any particular technology or manufacturer's products.

I hope you will find it understandable and useful.

Lightning protection CAN BE complete and bullet proof if enough resources and good engineering and testing are devoted to it. My best example of this is that commercial aircraft are directly struck by lightning about once/year. (Note: EACH plane is struck ~once/year!) Although there is occasional minor mechanical damage, the planes aren't downed, despite the heavy dependence on electronic navigation and control systems. That's because protection, and testing with lightning simulators, is an important part of aircraft development, and required for the FAA certifications.

Your home rig doesn't need that level of investment and testing, but you can easily do a lot to improve the security of your system.

(Dr.) Richard L. Cohen


 
RE: Lightning and Grounding  
by K6IHC on April 9, 2006 Mail this to a friend!
Good job in mentioning Panamax. I totally forgot about them as a resource for this topic. Panamax has been a respected company in the surge suppression/protection field for many years. I know this mainly because I live in the same city as Panamax's HQ.
 
RE: Lightning and Grounding  
by K8MHZ on April 9, 2006 Mail this to a friend!
Dr. Cohen,

Thanks for the link to Omega Power. The photos of lightning were awesome, especially the ones with the power lines in them. But the real treat was the videos!

10 kV into an alarm clock was great! The demo with the light bulb and the supressor was cool too.

Even if just for entertainment, the site is worth going to.

Thanks for posting,

Mark K8MHZ
 
Lightning and Grounding  
by N6JSX on April 9, 2006 Mail this to a friend!
Yes, read PolyPhaser - this is not a self serving entity trying to sell you devices!?!?!

Yes, when lightening hits damage will occur with protection or NOT.

Yes, power lines and telephone lines get hit more than HAM stations - dah - really, gee can't figure that one out.

The REAL question is are we attracking lightening with an elaborate PolyPhaser ground system. I sure cannot aford a PolyPhaser system so if my tower grounding is not a commericial PolyPhaser system AM I MAKING MY SYSTEM A LIGHTENING TARGET? I think so.

We can only aford so much grounding - will this amount of grounding TRUELY disappate a lightening hit or only attracked a HIT? HAMs do not have the space nor funds for a proper PolyPhaser system nor a Mil-Spec Test Lab system installed at Northrop so the hit dissapation will be minimal into our home-made systems - putting all protection devices/equipment in great jeopardy.

I've asked this questions many times with no REAL ANSWERS "but the self proclained wanna-be eHAM know -it-all engineering experts" will now go into a tirade of ripping responses.

Is gounding your tower making your tower/antennas equal to ground level potential really what we want to do?

Why I ask this, is I know of a 400' tower in Manitowoc, WI (highest point is miles) that has NOT taken a hit in many many many years. I suspect it is due to more than luck - the tower has two little 2-AWG cables from two legs of the tower to ground rods under the asphalt parking lot - the bunker only has one 2-AWG cable to a ground rod under the asphalt. The four tower legs are insolated from ground by 3' cement pillars. I suspect that the tower does NOT appear to be at ground potential but takes on the potential of the atmosphere it is in. Without a difference of potential lightening is not attracked to this tower. These little ground cables would act like a fuse to a lightening hit disappating very little energy into the ground before burning open. I also know of AM radio towers that are totally isolated form the ground - receiving very very very infrequent hits.

Now will this type of grounding protect towers? NO, hits can be random events jumping to the nearest conductor. So some proection is needed but unless you go to the total extreme of a PholyPhase system that can dissapate all of the HIT energy it may be prudent to install a gap grounding system NOT tieing it to absolute ground potential. Here is where spark gap type isolation devices would allow the tower to float at atmospheric potentials becoming less attractive to lightening, yet still yeild some protection.

I now live in flat-land Ohio and I've never seen lightening like I've seen here! These bolts have a diameters of 55 gallon barrels. I'm going to install a moderate affordable ground system connected to a brass plate in the wall of my house that will have "all" the coax lightening isolators acting as a barrier into the house. But my towers will have only minimal safety grounding with the intentions of allowing the tower to float, but if hit, still have some disapative protection relying on the brass plate barrier for entry protection.

The ultimate protection is removing my coax's from the brass plate - but this is not always practical when I'm at work or sleeping.

I'd like to hear more from the Commerical site HAM support engineers and repeater owners as to what they have seen and experiance rather than the eHAM myth generators.
 
RE: Lightning and Grounding  
by K8MHZ on April 9, 2006 Mail this to a friend!
"The four tower legs are insolated from ground by 3' cement pillars."

Sorry to sound disrespectful but you obviously know little about the subject. The contact cement makes with the ground is a very good, low impedance conductor, NOT an 'insolater' (sic)

It will be very hard for you to understand the nuances of lightning protection if you don't even have a handle on the basics.

PolyPhasers don't attract lightning, either. I don't even want to know where you are getting your mis-information but I hope you are smart enough to disconnect and not touch your equipment during a thunderstorm. If not, Darwin was right.

73 and stay safe,

Mark K8MHZ
 
RE: Lightning and Grounding  
by K8MHZ on April 9, 2006 Mail this to a friend!
"I also know of AM radio towers that are totally isolated form the ground"

Name two.

 
RE: Lightning and Grounding  
by K9KJM on April 9, 2006 Mail this to a friend!
There seems to be some confusion regarding copper "strap" Copper strap is a flat, Usually .026" thick strip of copper. This is the BEST conductor for a RF AND Lightning ground.
Copper "Braid" is a large number of smaller copper wires all woven into a "braid" Because braid can oxidize outdoors and cause serious RF problems, It is not suggested for a grounding material, At least outdoors. Commercial radio stations use it only to bond things that need to flex, Like a metal door to a metal door frame.
It is sad to see the old wives tales and 1950's wrong headed thinking still alive and well regarding lightning protection.

ANYONE who tells you that grounding a station is not a good thing is still in the dark ages.
For good up to date information about how to do it right, See: http://members.cox.net/pc-usa/station/ground0.htm
(Please READ the entire site and the links, Which will be a nice rainy day project just to read all this good info)
ANYONE who thinks that concrete is an insulator is VERY misinformed! To lightning, Most everything that we think of as an "insulator" is NOT!
For over 20 years now commercial buildings have been REQUIRED to bond to the "UFer" ground of the re-bar in concrete, Because it is one of the BEST grounds available! See: http://www.psihq.com/iread/ufergrnd.htm

AM radio stations have some of the BEST grounds available! ALL of them have at least 120 radial #10 copper wires a full quarter wave length buried! An AM radio station uses a pair of small brass or copper balls as a spark gap to discharge static charges.
The balls are set just far enough apart to not arc over during normal operations. I have seen them spark almost continous during storms, Dumping that energy to ground.

The 400 foot tower in Manitowoc not hit by lightning??????? HAW!!!! HOW DO YOU KNOW? I will bet that a properly installed lightning counter on this tower will show several strikes every year!
I know this to be a fact because ALL tall objects are struck by lightning on a regular basis. Towers with counters tell the truth!
The fact is that tower or its equipment may not have received any DAMAGE from lightning in several years.
That means its meager grounding did its job. REMEMBER lightning bolts come in all sizes, From very small to very large. It really does not take too much of a conductor to divert an "average" direct lightning strike to ground.
DAMAGE is caused when the object hit is a poor conductor (Like a tree for example) When a tree is hit the energy vaporizes the sap and will explode parts of the tree.
The power companies learned long ago that number 6 copper will provide protection to over 90% of strikes.
(It is cheaper for power companies to simply repair damage on the less than 10% than it would be for them to install something like 2/0 copper to EVERY power pole!) BUT go to a main substation and see how it is grounded! 2/0 copper at EVERY pole and steel object!

ANYONE who tells you that "Nothing can protect from a direct lightning strike" Really has his/her head deep in the sand (Or some other really dark place)

In the commercial world (Yes, I work on big towers, And own and operate several repeaters) A fair sum of money and effort is done to properly protect from lightning. (Police, Fire, Ambulance, etc radios are NOT disconnected at the first rumble of thunder) AND they do NOT suffer any damage from direct tower hits.)

That big money does NOT have to be spent! USED copper wire will provide every bit as good a conductor as brand new shiny copper! Strip off insulation and chuck it into a drill and twist a number of #12 house wires together to form a nice heavy gauge conductor!
Seek out upscale roof contractors that use copper flashing and get some scraps! (About the same stuff that the big companies would charge you big bucks for)
MAPP gas in a little hand held torch will flow true silver solder to make connections. (This is REAL silver solder, In stick form, Used to weld radials together on AM stations, NOT plumbing "silver solder" or soft solder.) It is really more properly called a high silver content brazing alloy.
Space ground rods twice the distance apart as the depth in normal soil.
Expensive arrestors are not usually needed, Check out I.C.E. (Industrial Communications Engineers) for quality lightning arrestors at a fair price. OR just get a coax switch that puts all unused antennas to ground when not in use.

Remember the basics: Use a "single point" ground, BOND ALL metalic objects and grounds together with as heavy a conductor as available, Install surge suppressors on your AC power entrance (Whole house arrestor) (As mentioned, More damage is done to ham equipment from AC line surges than hits to antennas)
While it is nice to have lots of ground rods installed like some of us have, It is really not all that important. Think about a BOAT, Or AIRPLANE! They dont have much in the way of ground rods, And they DO take direct lighting hits and dont have damage!
EVERYTHING looks like "ground" to lightning! Including things we think of as insulators! Like trees, houses, barns etc. The ONLY way to prevent damage is to give lightning a path to ground without going through our house, radio, barn or whatever!
 
RE: Lightning and Grounding  
by W8JI on April 12, 2006 Mail this to a friend!
Wow, there sure is a lot of folklore about lightning and equipment! Especially statements with a direct hit nothing is left!

My antennas get hit dozens of times a year, and I virtually never have any damage in my station and never have damage in the house. I leave everything connected because there are too many cables to disconnect.

Lo and behold, I don't even have very many ground rods. The ground rods I have are only 4-6 foot long. I don't have any lightning clamps other than surge strips for my TV sets and computers.

What I do have is common point grounds, a perimeter ground buss around the house, and lots of buried radials. I have all grounds and shields bonded at the entrance to each area, including power mains.

I have the tallest strutures for miles, including a 318ft tower, and I have miles of wire and feedlines spread out for thousands of feet in almost every direction.

The reason my opinion is different than other people's opinion is I have common point entrance grounds, use buried wires to disperse charge, and sensible wire routing.

You don't have to spend a lot of money to protect your equipment, you just have to do things right. It is also not true to say if lightning hits nothing will survive. I haven't lost as much as a computer modem from direct hits on my towers, and it all stays connected 24/7.

73 Tom
 
RE: Lightning and Grounding  
by W2FXG on April 12, 2006 Mail this to a friend!
I am having a new house built here in Tampa and from what I have seen when they built the model, they put a lot of rebar into the ground and throughout the cinder blocks before they pour the slab. If I connect to this infrastructure, is this a reliable perimeter ground for the house? I hope to run a cable to the rebar from a ground strip in the shack on the 2nd floor.

I plan to have a point of entry ground for where the cables come into the house at ground level with a copper plate for the connections and three rods driven 6 8 fanning out from point of entry.


Thanks for the great discussion.

- Ken
 
RE: Lightning and Grounding  
by K9KJM on April 12, 2006 Mail this to a friend!
By all means, Do bond to that rebar! As I mentioned earlier, Commercial buildings have been doing this for a long time now. A very good "UFer" ground.
See: http://www.psihq.com/iread/ufergrnd.htm
However, Do not rely on that for your entire ground system! Also provide at least one ground rod for any antenna mast, Your power entrance needs at least one, etc. (And they all need to be bonded together)
Good luck!
 
RE: Lightning and Grounding  
by W8JI on April 13, 2006 Mail this to a friend!
There sure are a lot of myths being propagated on this thread!

1. The average ham cannot protect his station.

What a pile! The vast majority of damage is caused by ground LOOPS through equipment, NOT GPR (ground potential rise). The best ground in the world does not do a thing when the lead routing and bonding is such that current loops through sensitive equipment. We can still avoid problems with the worse ground in the world if wiring is effective.

If everything enters a building using a single point ground, everything will rise and fall together during a hit. The only currents will be parallel currents on lines, and while they can cause damage it will be nowhere like looping the lightning current through the house.

EVERYTHING metallic entering should be bonded to the same ground as the power lines, telco lines, and any CATV lines. That takes care of most damage people experience.

Case in point? I get many hits a year on my towers. My TV sets, computers, and stereos don't have grounds. What they do have is a single point entrance to the AREA of the equipment where all power, telco, and antenna leads come to one point and share a FLOATING "ground" or common point that is tied to the electrical safety ground wire. I don't lose any TV sets or somputer modems despite not having a big ground system on them. The actual ground path is through dozens of feet of very small wire.

2.) Insulating a tower will allow it to charge to sky potential, or reduce chances of a hit by reducing voltage gradient.

That's just nonsense. The charge is in the cloud. The thing that keeps it from arcing to earth is the very wide spacing. You can't bleed off that charge without returning charges to the cloud, and you certainly can't insulate something and let it rise to the charged potential of the cloud!

One foot of extra air gap isn't going to do a thing when the arc path is 2000 feet long.

Static dissipators on earthbound structures, insulating, grounding. None of it makes any difference. It's all snake oil and myth.

It's so illogical I can't imagine why people consider they can control hits without reducing the height, or changing the shape of the structure. Both reduced height and making an object "blunt" or wide and smooth will reduce charge gradient. A water tower is less likely to get hit than a pointed tower the same height, and a lower structure less likely than a taller structure less likely to get hit.

3.) A few rods, even if very deep, are a good ground.

It takes surface area and contact with soil to make a good ground. A good ground does NOTHING if the wiring is poorly configured. I'd rather have no grounding at all with good wirring methods than a good ground with poor wiring.

I've had towers over 100 feet tall since the 1970's. I've made hundreds of commercial installations, many on buildings where we couldn't get a ground. By proper wiring and single point entrances to equipment, I've had dozens of repeaters and all of my ham gear survive direct hits for years. Without any extreme measured and long before anyone ever heard of a MOV or coaxial lightning arrestor I can count the number of pieces of gear damaged over the past 30 years on one hand, and all of it was minor.

Wire it correctly and avoid ground loops, and that's the bulk of the game. You can polish it off with a good ground and surge protectors. Otherwise just buy a rabbit's foot and hang on the tower, that's just as effective and scientific as insulating it or using a static dissipator.

My neighbor the CBer uses a glass jar with salt water as a ground, and pie pans on his coax to deflect lightning. I thought that was odd until I read some of the stuff posted here, especially concrete insulators.

73 Tom
 
RE: Lightning and Grounding  
by K8MHZ on April 13, 2006 Mail this to a friend!
Bonding to re-bar in an existing structure is not the same as a Ufer ground, but similar.

Ufer referrs to *supplimental* grounding using concrete encased electrodes. If re-bar is used it is to be bare or zinc-coated. See 250-50.

Also, a Ufer ground relys on rods that are 20 feet long and bonded together. ALL metal in a floor used for grounding MUST be bonded together BEFORE the pour. Where re-bar protrudes out of the concrete for connection it is also required to be bonded to at least one other electrode as described in Article 250, Part C.

Also, the use of a vapor barrier in the construction of the concrete floor destroys the earth to concrete connection making it unsuitable for use as a concrete encased electrode.

For a standing structure, rods plural should be used as your source for dissapation with the re-bar bonded for safety. I would NOT use re-bar as a primary ground in a standing structure as there is little chance it was built properly for grounding purposes.

73,

Mark K8MHZ

 
RE: Lightning and Grounding  
by K9KJM on April 13, 2006 Mail this to a friend!
My experience over the years has been similar to W8JI's and I agree with him completely. The little "ground" wing nuts on the back of my radios are not connected to anything. Have not been since the mid 1970's when "single point" grounding became the way to do it.
And yes, As I mentioned, Rebar in concrete is a good supplement to your ground system and NEEDS the rods also. Even if that rebar is not properly bonded together, Whatever bars you can attach to will add to your overall ground. Therefore a very good thing.
I started bonding to rebar in 1982, And not all of the rebar was bonded together. These jobs were tower building footings, Right at the base of very tall commercial towers (That over the years have taken many direct lightning strikes with NO damage to equipment (Or the concrete)
 
RE: Lightning and Grounding  
by K8MHZ on April 14, 2006 Mail this to a friend!
"My neighbor the CBer uses a glass jar with salt water as a ground, and pie pans on his coax to deflect lightning. I thought that was odd until I read some of the stuff posted here, especially concrete insulators."

The CBers around here say the best grounding electrode is to take a piece of 2 inch PVC and put the rod in the PVC with fertilizer and bury the whole thing.

Obviously this is a mythical version of an electrolytic ground rod. Now, looking at the whole thing as a system, it appears that the explosion the fertilzer would make when subject to half a million volts or so should turn the ground rod into a rather formidable projectile. This may be why larger wire is recommended when using a PVC ground system as smaller wire may not be able to restrain the moving mass of a flying 10 foot long copper electrode.

I almost forgot about the CBer's electrode. Thanks for sharing your version with me.

73,

Mark K8MHZ

 
RE: Lightning and Grounding  
by K8MHZ on April 14, 2006 Mail this to a friend!
Could this lead to a new product line from PolyPhaser?

"LONDON - Two women were killed by a bolt of lightning in Hyde Park when their underwired bras acted as conductors, a coroner said Wednesday. "I think this was a tragic case, a pure act of God," coroner Paul Knapman told an inquest into the deaths. He recorded a verdict of death by misadventure. The two women, Anuban Bell, 24, and Sunee Whitworth, 39, had been sheltering under a tree in the park during a thunderstorm. Pathologist Dr Iain West said both women were wearing underwired bras and had been left with burn marks on their chests from the electrical current that passed through their bodies. Death would have been instant, he said. The bodies were not discovered until the following day because passers-by thought they were vagrants."

 
RE: Lightning and Grounding  
by N4ZKF on April 23, 2006 Mail this to a friend!
I have been a Site Supervisor for one of the big tower companies in the US for about 6 years now.
I supervise the installation of all the cell carriers on our sites during collo activity.
You are right on the money with the protection. A ground buss up top, a ground buss at the bottom, and polys on a buss right before the jumpers to the equipment.
I have installed mine like this on my tower also. I HAVE sustaned a direct hit and it never made it to the shack. The antenna took it hard, the tree 5 feet away caught on fire but my radios never blinked.
I live in Florida. The bigger the "ground ring" the better. 5 ohms or less is what to shoot for in the meggar when creating the ring.

Dave
n4zkf
n4zkf@n4zkf.com
dxc.n4zkf.com
cluster node
 
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