Grounding an Antenna

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Old 05-04-18, 04:56 PM
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Grounding an Antenna

I installed an exterior antenna with rotator, and I'm trying to figure out how to ground it. The more I read, the more confused I get. As I understand it, I screw a coax grounding block on the outside wall near where the antenna cable enters the house. I run the antenna cable to it, buy another piece of cable and run it from the tv outside to the block. Can the block be inside? Do I do the same sort of thing with the rotator cable? The rotator cable has three wires and I would need to wire it into something.
Then, as I understand it, I attach a #10 copper line to the antenna mast - I assume below the rotator? How do I attach it? Then I'm not sure what to do with it. I think a grounding rod is out of the question. The land all around here is full of rocks and it would be very difficult to find a spot where the rod would go further into the soil than five inches. I have a large copper wire coming out of my electrical box that eventually attaches to a copper pipe. Can I run the ground wire down from the antenna into the basement and attach it to any cold water, copper pipe? What do I use to attach it?

Thanks for your help guys!
Martha
 
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Old 05-04-18, 06:54 PM
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I forget what it is called but they make a grounding block for antennas, telephone equipment, etc. which you attach to the fat ground wire coming out of the panel. Then you connect a (I think 10 gauge copper is good enough) from this block to the antenna mast.

For those who do drive a ground rod (8 foot) below the antenna, that ground rod must be connected to the panel with a #6 copper wire run outdoors as much as possible and preferably against the foundation. If the newly run #6 wire first reaches another fat wire running from another ground rod to the panel it may be spliced onto that pre-existing ground wire there. The grounding block for the antenna is attached to the #6 wire coming closest to the antenna.

The grounding block for the coax is also connected to or attached to one of the #6 ground wires mentioned above.
 
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Old 05-04-18, 07:07 PM
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So the grounding wire goes from the antenna mast to the grounding block and then to the copper wire coming out of the electrical box? How do I clamp it on? Does the grounding wire connect to the antenna below the rotator? Is this grounding block the same grounding block where I ground the antenna coax cable? Do I ground the rotator cable?
 
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Old 05-04-18, 07:19 PM
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I believe Allan was looking for the term intersystem bonding terminal . These can be clamped onto the fat grounding wire coming from the panel. It will have additional spots for other grounding wires.
 
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Old 05-04-18, 07:35 PM
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So the 10-gauge copper wire goes directly from the antenna mast to the intersystem bonding terminal clamped to the fat wire that is coming out of the electrical box? It isn't connected to the grounding block that the coax cable goes through?
 
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Old 05-04-18, 08:04 PM
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The coax ground should also go to the bonding terminal .
 
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Old 05-04-18, 08:40 PM
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Does the grounding wire connect to the antenna below the rotator?
You can attach the ground wire to one of the nuts on the u-clamps for the mount.

Do I ground the rotator cable?
No.

Is this grounding block the same grounding block where I ground the antenna coax cable?
Yes. You use a coax ground block like shown below.

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Old 05-05-18, 04:33 AM
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Can the coax ground block be indoors? I understand that the copper wire connects to the bonding terminal. But does it also connect to the coax ground block? If so, do I have this right:
The copper wire runs from a nut on the U clamp on the mast to the coax ground block and then to the bonding terminal on the copper cable coming out of my electric box. The coax cable runs to the same ground block, then to the tv?
Do I need to turn off the electricity when connecting to the copper wire?
 

Last edited by mmorris1; 05-05-18 at 04:55 AM.
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Old 05-05-18, 10:48 AM
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Usually the coax ground block is outside but it could be at the main panel location. The ground line from the antenna doesn't have to run thru the coax ground block but they do connect at the same location.

No..... you aren't working with any live wiring so there is no need to turn power off.
Different story if you are inside the panel.
 
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Old 05-05-18, 06:39 PM
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What do you mean, they connect at the same location?
 
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Old 05-06-18, 06:19 AM
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The same location -- The intersystem bonding terminal block, which under current code has to have enough screw terminals so at least three things (antennas, etc.) can be easily connected there.

One point I overlooked was that as of the 2008 NEC code, the IBT has to be "close to" the main panel. Whereas if the grounding electrode conductor (fat ground wire) from the panel goes some distance to the ground rod, I had suggested earlier that an IBT might be attached to that wire near the far end.
 
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Old 05-06-18, 06:41 AM
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So, the copper wire runs from a nut on the U clamp on the mast to the coax ground block and then to the bonding terminal on the copper cable coming out of my electric box. The coax cable runs to the same ground block, then to the bonding terminal.
So if the coax antenna cable and the copper wire both run to the block and then to the IBT, where does the coax cable run to the tv?
 

Last edited by mmorris1; 05-06-18 at 07:22 AM.
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Old 05-06-18, 07:34 AM
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The coax cable runs to the TV, possibly with a joint at a coax grounding block, without necessarily following the route of any ground wire.

Because lightning can infiltrate the coax, a coax grounding block is recommended and positioned outside as close as practicable to the point where the coax enters the building.

A coax grounding block is positioned to optimize the route of the coax from antenna to TV, not to optimize the route of the (ground) wire from the coax grounding block to the intersystem bonding terminal block.

Another advantage of the properly installed and connected coax grounding block is, for coax coming from cable TV systems, there is some protection from faults in the cable company equipment up on the utility pole.
 

Last edited by AllanJ; 05-06-18 at 07:53 AM.
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Old 05-06-18, 08:05 AM
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So the coax antenna cable runs from the antenna to the grounding block and then to the tv.
The ground wire runs from the antenna to the same grounding block and then to the intersystem bonding terminal block. Is that correct?
It was the "they" in "they connect at the same location" that threw me.
 
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Old 05-06-18, 11:57 AM
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Does it matter if the grounding wire touches the metal cellar doors on its way into the house?
 
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Old 05-07-18, 08:12 AM
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No it does not matter if the grounding wire touches the metal cellar doors or other metal objects.
 
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Old 05-08-18, 06:48 AM
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Thanks all. I had to order the grounding block and when it arrives I'll put it all together.
 
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