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I recently moved to a storm prone area, so I plan to disconnect my shack connections when not operating. An electrician is helping me install a ground rod (bonded to my utility ground) soon, but I want to understand how thoroughly I need to disconnect to be safe.

Before moving here, I only ever operated QRP so having a ground rod at my home QTH is new to me. I'm not sure how much safety it gives me. I already have the ARRL grounding book, but it doesn't answer all my questions.

Questions:

  • Is my house safe if I disconnect only the short internal feedline, but leave the long external one connected? The feedlines will be joined by an alphadelta lightning arrester that's mounted to a copper buss bar affixed to the exterior of my house. If it matters, the longer feed line goes to an EFHW antenna I built, which is strung up in the back yard.
  • Do I also need to disconnect the ground braid from my exterior buss bar, that comes into my house? Is there any risk of a lightning strike following the ground braid?

I'm concerned because the external ground bar will be affixed to my house's siding. I want to ensure a nearby lightning strike couldn't cause some kind of sparking that would cause problems. I imagine that's what the alphadelta arrester is meant to take care of, but I'm not 100% sure.

Kevin Reid AG6YO
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User5754448
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  • Does your house have lightning rods? – pgibbons Aug 23 '21 at 11:41
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    No, just regular utility ground. I don't have any roof mounted antennas. – User5754448 Aug 23 '21 at 14:05
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    Ok, let's think about the lightning strike. It hits your antenna in your yard. The insulation on the feedline means nothing to the lightning, it will go right though it. I would think 98% of the energy will go into the ground right below the antenna. 2% is still a lot. Your surge arrester takes care of most of that but you're still not 100% protected. Disconnecting the cable after the surge arrester will be 100% protection (except if lighting hits your house). By disconnecting it, you create a large air gap the remaining potential from the lightning can't bridge. – pgibbons Aug 23 '21 at 14:19
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    If you use an antenna switch instead, keep everything connected but switch it to another port that goes to ground for example, this may also work, however the "air gap" in the switch will be much smaller but after the surge arrester I think you'll be 100% protected too. – pgibbons Aug 23 '21 at 14:20
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    The last thing i'll say, your surge protector may go up in smoke (I think that's possible), so if you're worried about sparks, don't install it on your house but a few feet away or use a metal plate as a firewall. – pgibbons Aug 23 '21 at 14:22
  • Ok, I'll add one more thing. I'm now "afraid" to post answers because this Voltage Spark person keeps deleting my answers and harasses me about it so I'm going to stick to comments now. – pgibbons Aug 23 '21 at 14:24
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    @pgibbons Please do post an answer instead of comments. I don't know who “Voltage Spark” is but they are not a moderator here and have no authority to delete your answers. Comments are best used for discussing improving the question, not for answering it. – Kevin Reid AG6YO Aug 23 '21 at 14:41
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    Does this answer your question? Lightning strikes nearby and coaxial cable – rclocher3 Aug 23 '21 at 22:04
  • @pgibbons Kevin is correct. Maybe this happened on another stackexchange.com site? ham.stackexchange.com is completely separate. Regardless, your comments are useful! Kindly copy them to an answer, so you can get credit and upvotes. Nobody is going to close your answers, etc. for no good reason on our watch! :-) – Mike Waters Aug 23 '21 at 22:12
  • @pgibbons "after the surge arrester I think you'll be 100% protected too" is a large overstatement. A surge protector is like that one strong carabiner between your climbing harness and the rope. It won't stop you dying if it's in your pocket or clipped casually to your pack. There are a lot more links in the chain to make you safe. The answers Phil links to are a good starting point. – tomnexus Aug 27 '21 at 04:40
  • @tomnexus i meant surge arrester + antenna switch that is directing the left-overs from the surge arrester to ground and has a small air-gap to the port that actually goes to the radio stuff. – pgibbons Sep 05 '21 at 18:04
  • I also read somewhere (w8ji) that you can't cut off the lighting, even if it hits the ground, the potential in your whole property goes up and the best you can do is ensure that the potential rises equally everywhere. You should check out his site, tons of info on grounding, lightning and much more. I'm reading his whole website actually, so much good info. Also thank you Kevin and Mike, you guys are too kind :) – pgibbons Sep 05 '21 at 18:07

1 Answers1

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Is there any risk of a lightning strike following the ground braid?

Not only a risk, it almost certainly will. Soil has some significant resistance, so when there's a strike on your antenna, on the powerlines, or on the ground anywhere nearby, the potential between your two ground rods is substantial, and so too will be the current through any conductor between them.

See How can I protect equipment against a lightning strike?

Phil Frost - W8II
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