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Author Topic: Unhooking Station Equipment Before A Thunderstorm  (Read 3679 times)
K0JEG
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Posts: 638




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« Reply #15 on: May 16, 2013, 06:01:29 AM »

For one, any given house has many unused cable TV jacks and electrical outlets. Don't these present just as high of a risk of arcing if if the cable or electrical service is hit by lightning? I'm not going to go plug a TV into all of them am I?

Actually you should only activate outlets you intend to use. For one thing, you don't split the signal as much and might improve picture quality. If you happen to live at the end of a line any unterminated lines could cause reflections as well. Also, your cable TV line should be grounded/bonded to the electrical ground rod, along with your phone lines. This is more of a safety issue for the CATV installer, since if for some reason your neutral would be disconnected the cable drop would make an excellent substitute (for a while, anyway).
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AK4SK
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« Reply #16 on: May 16, 2013, 07:55:29 AM »

I appreciate all of the replies, although some of them were off topic a little. I'm not really concerned with when to disconnect my station. I'm a native Floridian so I know a little about the dangers of lightning. My station at my old QTH (I'm still setting it up at my new place) was well grounded and I always disconnected at the inside bulkhead anytime there was a 20-30% chance of thunderstorms or better. Often in the summer I connect my station only when in use and disconnect it immediately afterwards.

I am really trying to understand if there truly is an added risk to have my equipment unhooked, leaving the inside bulkhead connections not connected to anything. By added risk I mean greater than what my house would have without a station at all (not counting the fact that the antenna attracts lightning). A typical house has many points where lightning can enter and do damage. Does having an amateur radio station with coax bulkhead connections on the inside not connected to anything increase that risk? As stated in my original post some people are adamant that there is a huge risk of doing so. I'm not trying to argue with that, but thinking through it I disagree for the reasons I stated in my original post, it just doesn't pass the common sense test.

If you consider the case where everything is identical (house, antenna, radio, etc.) and even throw in a properly grounded antenna mast and entrance panel except house A leaves everything connected and house B disconnects everything is there really a greater risk that house B is going to incur more damage than house A from a lightning strike? Common sense tells me probably not. To me my radio or some other piece of equipment is just as likely to catch fire and burn the house down in the house A example as there is a chance of an internal arc across the room that causes a fire. Or it is just as likely that lightning hits the main electrical service entry or cable TV entry and does damage to my house either by causing damage to a connected TV or other piece of electronics or arcs from one of the many cable TV jacks or electrical outlets. If what I'm saying is plausible, then there really isn't much justification to keeping my station connected, especially since it is much more likely to get damaged being connected. Now, if what I'm saying is completely false, and unhooking my station significantly increase the chance of major damage to my house then sacrificing my radio for the sake of my house is the way to go. But only if the risk is significantly greater, otherwise I'm going to unhook my equipment.

Does that make sense?
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K1CJS
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« Reply #17 on: May 16, 2013, 12:23:16 PM »

No, the risk is not significantly greater.  If you have a properly installed grounding system, I wouldn't worry about leaving the equipment connected.  

As I first said, however, if you get a direct strike you're going to have some damage.  Even a home with no ham equipment or antenna systems would.
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AK4SK
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« Reply #18 on: May 16, 2013, 12:35:55 PM »

No, the risk is not significantly greater.  If you have a properly installed grounding system, I wouldn't worry about leaving the equipment connected.  

As I first said, however, if you get a direct strike you're going to have some damage.  Even a home with no ham equipment or antenna systems would.

Thanks, you answered my question. I think even commercial stations get damaged from time to time so I'm under no illusion that I can completely prevent damage. Once every few months a house around here gets hit and catches on fire as it is. I just want to do the best that I reasonably can.
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K4SAV
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« Reply #19 on: May 16, 2013, 02:25:19 PM »


If you consider the case where everything is identical (house, antenna, radio, etc.) and even throw in a properly grounded antenna mast and entrance panel except house A leaves everything connected and house B disconnects everything is there really a greater risk that house B is going to incur more damage than house A from a lightning strike? Common sense tells me probably not.

See, you knew the answer already.  It might be the other way around.  Equipment that is disconnected close to the equipment is less likely to sustain damage.  It's easy to misinterpret what people say on this subject because many never state things clearly.  Like this thread for example, where people are talking about disconnecting equipment.  Many never say WHERE the disconnection is that they are talking about, and that makes a huge difference.

There are those, you notice, that think you will have damage from every lightning strike regardless of what you do and you can't prevent that.  That of course is totally false.  That may be due to their own personal experience of having a poor grounding system and not recognizing it.  There are many examples of surviving lightning strikes with no damage, including my own system, 2 to 3 direct strikes per year average for 8 years with no damage so far.  You can never get to zero probability of having damage but you can get to a low probability with a good grounding system.  For someone to say everyone will have damage with every strike is easily disproved.

Jerry, K4SAV
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W5WSS
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Posts: 1652




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« Reply #20 on: May 16, 2013, 03:16:49 PM »

An FDP-8 TV wall receptacle has an output connector behind for continuation along the daisy chain where one can properly connect the coaxial cable going to the next place...but if one is used at the end of the drop a terminating resistor can be installed there and this is designed to prevent reflections traveling backwards along and to the previous outlet.

A single point Station entry panel bonding with a short wide strap and lightning arrests connecting both center conductors and Shields of coax and anything else that is vulnerable from outside entering through that panel located between the antenna and equipment should be connected to a earthing rod that is in turn connected to the Ac mains entry panel with same treatment andany and all rods should be bonded together. bonded earthing rod to earthing rod.

When those rods are properly bonded along with proper single point entry panels being grounded is the important aspect therefore disconnecting the equipment from that single point earthing panel is perfectly OK along with disconnecting the station feedlines and control cables it is acceptable to also disconnect the station and all accessories from the ac outlets.

When the system is working properly the bonded rods should help to keep a large percentage of damaging electricity off the electrical wiring proffering to go to earth ground via the averaged lessor path of resistance flowing into the rods
73.
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AA4PB
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« Reply #21 on: May 16, 2013, 03:27:24 PM »

Most lightning damage is not caused by a direct 30,000 Amp hit to the antenna. It is caused by magnetic coupling when a tree or something nearby gets hit. Its fairly easy to protect against this secondary damage. If your typical aluminum ham antenna gets a direct 30,000 Amp hit there will likely be damage to the antenna system. Even so, a good single point grounding system can protect the house and electronic equipment located inside.

If you have a lightning rod (antenna) sticking up in the air you would be wise to provide a low impedance path to Earth outside of the house.
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K4SAV
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« Reply #22 on: May 16, 2013, 04:05:24 PM »

If your typical aluminum ham antenna gets a direct 30,000 Amp hit there will likely be damage to the antenna system.

That's actually a true statement, but only because the "typical" ham antenna system isn't designed to handle a direct strike.  The "typical" ham antenna has very poor grounding, many with no grounding at all, many depending on a coax to be the major lightning current carrier, and a multitude of other problems that cause the system to fail.  Hams with good grounding systems are certainly in the minority, and are not typical.
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LA9XSA
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« Reply #23 on: May 17, 2013, 06:03:30 AM »

What causes a bit of confusion here is those people we sometimes get who ask about disconnecting their gear in case of lightning, and who have no ground system. "Hey guys, I'm gonna skip the ground system and just disconnect the coax from my radio when I hear thunder, and leave the coax lying on the table". In that case, disconnecting might indeed be making things worse since instead of their radio going up in smoke, they start a fire on their desk. Or not. It becomes pretty unpredictable.

As already answered, if you have a good common ground system where the antenna feed lines, and all other conductors already are connected to ground, then disconnecting the gear inside would be slightly better than leaving them connected - much like if you put the gear in a faraday box to protect against EMP, you want an insulating layer/gap between the surface of the box and the protected equipment. The gap on its own does nothing to prevent lightning damage, it's the box/common ground system around it that does actual the protecting.
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W5WSS
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« Reply #24 on: May 17, 2013, 07:47:51 AM »

La9xsa Yes! That is correct. Smiley
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AK4SK
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Posts: 150




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« Reply #25 on: May 17, 2013, 01:54:57 PM »

Thanks everybody, I appreciate all of the help.
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W4VR
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« Reply #26 on: May 17, 2013, 02:27:28 PM »

If your antennas come in through a bulkhead, you should ground everything at that point when you are not using the radio.  If you have a remote antenna switch outside, as I do, wire the switch so that when it's off every antenna is grounded at that point.  Disconnect the coax going to your shack at the switch.  Make sure you also disconnect the control cable for the switch at the switch.  Just disconnecting things is not enough...you also have to ground everything.
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W9KDX
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Posts: 770




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« Reply #27 on: May 17, 2013, 04:21:26 PM »

When a lightning strike has already arced across a couple miles of air, what is the
likely hood that a few more feet between the socket and the disconnected plug is
going to stop it?


That is not at all what I am trying to accomplish here.  Obviously, a direct strike to your house is catastrophic and anything can happen.  However, just because an object is sitting s few yards from an electrical outlet doesn't mean that is where the lightning will go.  Also, even a proper ground can do little to stop a direct strike.  For me, I disconnect because I don't want to find out the hard way that something weird, some static build-up, or something next door fried thousands of dollars of equipment because it was connected to something.  Nothing else I have plugged in comes even close in value, so it is worth the extra time to disconnect it every time.  Of course this system won't work if I forget; nothing works if you don't use it.  But I still hold that anything sitting alone, ungrounded, connected to nothing but a wood table is less likely to be the target of whatever might hit my house or the surrounding area. 

I am not looking for a solution that is 100%, there is no such thing if we are to live above ground.  I just want to increase my odds.
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Sam
W9KDX
K1CJS
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« Reply #28 on: May 18, 2013, 04:36:08 AM »

Not trying to be repetitious, but there are some things that should be kept in mind and considered.  First, lightning protection is a matter of degree.  If you go the way of professional installers at commercial sites, there are ways of protection that will eliminate just about any damage to the gear inside the building.  Of course, that involves spending money--in some instances, a lot of money.  For example, I know of sites where a well driller was called in to sink a well casing down to the water table to be used as a "ground rod".  Other commercial sites rely on a ground halo around the building connected to multiple ground rods driven in along that halo.  In any event, usually the ground systems of such sites cost more than what an average ham has in his shack in dollar value!  Such sites may occasionally lose an antenna or have some minor hardware damaged, but little else happens to them, even if a direct strike occurs.  You've got to ask yourself how much you think you need for protection, how much you're willing to spend--and how far you want to go to achieve what you're trying to achieve.  It is possible to get near that 100% protection--if you're willing to go to the extremes that a commercial site does.

To the matter of equipment just sitting on a table or desk, the risk is no more or no less than to any other piece of electronic equipment in the building.  Consider your television--it has a connection for an antenna.  Having an antenna attached to it doesn't affect the risk unless a direct strike occurs or the ground system is either inadequate to begin with--or has been disconnected.  A ground system should be robust enough to drain static charges and induced voltages at the very least--or it isn't much of a ground system.  There are documented instances of a lightning strike coming down a conductor outside a building, then jumping to another conductor inside that same building, then outside again to find a ground point! 

No matter what you may or may not do to protect your equipment, it could get damaged anyway.  The best you can do is to take all the precautions you can--just as you seem to be doing.  A monthly inspection of your station bulkhead/grounding panel and the ground connections will add to your peace of mind too--by making sure nobody has inadvertently tampered with or disconnected something that shouldn't have been tampered with to begin with.  Such an inspection should be done immediately if any utility workers have visited your home for any reason, since there are instances of service personnel who have disconnected attached ground wires for odd reasons.  73!
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K4SAV
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« Reply #29 on: May 18, 2013, 05:14:02 PM »

After hams put up antennas, locate their shack, and run wires, the last thing they think about is lightning protection.  It should have been the first thing they thought about.  After you do all that, many have situations where adequate lightning protection cannot be installed without starting over and reconfiguring their station.  You could say that is expensive.   

If you plan the ground system before you install antennas and runs wires, usually the cost is not very expensive at all.  It used to be really cheap before the cost of copper went crazy.  Eight years ago, I think I spent about $270 on my grounding system with 11 ground rods, 200 ft #4 wire, and 15 single shots (before copper went crazy).  Most people don't need that much stuff, although individual items will be more expensive today.  A few ground rods and some ground wire is what you need, but most of the protection comes from the way you connect things together.  Yep, you can dream up a system where things can't be connected properly.  Don't do that.  And you can erect antennas that can't handle lightning strikes.  Don't do that, or don't put them next to your house (assuming you really want lightning protection).

Yes you can still get damage even if you have a good grounding system.  Lightning could miss your antenna and hit directly on your house.  If you live in an area of high probability of that, I suggest that you need lightning rods on your house.  Most people will just consider that to be a low risk item and ignore it.  A lightning protection system should be designed to protect the most valuable items, like your rig, antennas, and things inside the house.  It isn't worth the effort to try and protect small stuff, like a piece of coax, loading coil, Beverage antenna, or misc stuff like that since most of that has a low probability of getting damaged anyway and even if it does, the cost to replace it is low.

So lightning protection is not expensive, unless you didn't plan for it and end up with an antenna system that is impossible to protect.  The key to doing this correctly is knowing what to do, although I must admit that is sometimes difficult given the large amount of misinformation available on this subject.

Jerry, K4SAV
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