rooftop antenna grounding clarification request - AVS Forum
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post #1 of 4 Old 08-12-2012, 11:52 AM - Thread Starter
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I've spent a couple hours reading about this now, here and other sites, and my head is spinning. Please help!

SITUATION: I bought a small outdoor antenna (RCA ANT751R) to mount on the roof of the house we recently purchased. This is a 50's "modern" split level house that has a flat roof & is shaped roughly like a "Y" (three "wings") with the location of both where I am running the coax in/where the power lines enter the house in the junction of the three lines of the "Y" (i.e. in center of house/rooftop). The electrical service panel is also in the center of the Y, but in the basement, directly beneath where the power lines enter the house (the thick metal pipe that connects to the service box runs straight up & out the side of top level roof line, with a few inches of the pipe (I believe the term is conduit, but am not certain that is right usage) protruding out. We are fairly close to the stations I want to receive, but in a wooded area, so I am more concerned about line of sight than altitude, and consequently the antenna is mounted to a lower rooftop, and is actually beneath the level of the top flat roof level, should that matter.

Walking around the house, there is only one grounding rod driven in the ground, where the phone and cable service enters. This grounding rod is NOT connected to the main service panel, or directly to anything inside the house. It is only connected to the phone and cable service boxes on the exterior wall nearby. Also, the way I can wobble the rod, and the fact that it is literally 1 inch from the house, makes me seriously doubt it is anywhere close to 8' deep

I hope this is clear, and can provide pictures if necessary.

QUESTION: I'm trying to figure out the best/easiest (ideally they are one & the same!) way to ground the antenna/cable.

Based upon what I've read, it will not be good to ground the antenna & cable to the existing external grounding rod, unless I also in turn run a #6 copper wire to the service panel. Since this grounding rod is at the end of one of longest leg of the "Y", going there seems like even more trouble than just putting in a new rod in a more accessible location (I think the only reason I would try to utilize it is if there is a safety issue with the existing phone & cable hookups? I'm not sure. And if there is, it seems like something they should fix because they installed it, no?)

What is a LOT more appealing to me, in terms of ease of setup (& maybe even effectiveness?) is to ground the antenna to the existing pipe that comes straight up from the electrical service main from the basement. This is literally 4 feet from where the coax is entering the house.

But is this proper/safe? What I've read has my head spinning. On the one hand I've read that you should not have the path to ground run through the house, and this would. But ... isn't the power line doing the same thing? On the other hand, I've read repeatedly in comments from people that sound knowledgeable is that what you are really trying to do here is just reduce the potential of attracting a lightning strike, not protect from the consequences of one. In this mode of thinking, I want to focus on just making sure there is no static buildup, which seems like it may be best served (have the shortest cable run, etc) by grounding to that pipe. And as I mentioned, we are in a very heavily wooded area, with tree cover spanning almost the the entire area above the roof and antenna (the antenna LOS is literally "peeking below" the branches of a couple huge trees) and this is a modest antenna isn't even as high as the top level roof line. So it seems very improbable (to me, a layman who could be completely wrong about this, lol), that the antenna itself would take a lightning strike anyway -- the bolt would have to literally travel through tree cover to hit it.

Any guidance would be greatly appreciated. I literally don't know if this (grounding to the main service box conduit at the point it exits the house) is the best idea, or the worst idea possible.

p.s. curiously the installation manual for my antenna says absolutely nothing about grounding it!
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post #2 of 4 Old 08-12-2012, 03:21 PM
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You might want to check the Wisconsin electrical code, but NEC allows grounding to a metallic service raceway (the pipe your electrical service comes in through). Use a listed ground clamp. If you are worried about safety, the NEC is all about safety. If you decide to do this, please be very careful around the exposed conductors.

FWIW NEC requires that ground rod be bonded to the house's grounding electrode system. From the standpoint of lightning, what you are trying to do is equalize potential to prevent flash over.
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post #3 of 4 Old 08-14-2012, 06:35 PM - Thread Starter
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OK, now i have some proper terminology. What I am asking is if I can ground the antenna to the service entrance weather head. What I have determined so far is that this may be a bad idea, unless I can connect the ground at least a foot down the conduit, away from any conducting lines.
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post #4 of 4 Old 08-14-2012, 09:30 PM
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Quote:
Originally Posted by puddnhead View Post

...ground the antenna to the service entrance weather head.
No.
Quote:
...bad idea, unless I can connect the ground at least a foot down the conduit, away from any conducting lines.
Yes.
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