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    kipp438's Avatar
    kipp438 Posts: 2, Reputation: 1
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    #1

    Aug 13, 2010, 12:15 PM
    Do I need to bond a grounding rod I installed for an antenna to my home's ground?
    I am installing an antenna on my roof. I bought some coax with ground wire attached that I am going to attach to a grounding block at the coax entry point. To the grounding block I am going to attach a #6 bare copper wire to an 8ft copper clad grounding rod. Is this sufficient as is? I read conflicting information on if I need to run yet another wire from the rod to my home's main ground, which is the water pipe where it enters my home.

    If this is sufficient, Ill just leave it, but if I really need to add another wire I will, but that raises some more questions. Since the main ground is almost on the opposite side of the house, I would need to round a corner by my deck, and word is, I can't go 90 deg with it. Having a big wire looping around there would be in the way... So can I bury this extra wire a couple inches and run it around my house to the main ground?
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #2

    Aug 13, 2010, 01:08 PM
    All grounding electrodes must be bonded together, per National Electric Code.

    You should check with local inspector as to the depth of the grounding conductor. The NEC is not clear, at least to me, how deep this conductor should be.

    If I am right, he should require burying it 24 inches, if not in conduit. That is my interpretation of the NEC text and tables.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #3

    Aug 13, 2010, 02:12 PM

    Ideally, you need to bond to the mast AND the coax needs to be grounded too Usually at the closest point of entry.

    DX Engineering - Antennas, Antenna Systems and High Quality Antenna Components! has some nice ground braid and screw clamps with studs.

    Although DXengineering has a nice antenna mast grounding block, but it seems only suitable for PL259 and type N connectors.

    The coax should be bonded to the single point system. No question about it. Where? As close to the point of entry as possible.

    The mast, I feel could be grounded to a separate ground rod.

    This solves two problems:
    1. A direct hit to the antenna will go directly to ground.
    2. The system (coax) is tied to the equipotential system of the house.

    If this were a detached antenna tower, this would be how it would have to be done.

    If your using a rotor, remember to ground strap around the rotor.

    My $.02.

    Best wire to use for the feed is RG6 Quad shied. Best connectors are compression. There are two types of RG-6: One with a copper plated steel core and one for solid copper. Issues with the steel core only arise when powering things like antenna rotors especially the Rotor 100 from Eagle Aspen.
    kipp438's Avatar
    kipp438 Posts: 2, Reputation: 1
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    #4

    Aug 14, 2010, 05:47 AM

    Thank you both for taking the time to answer my questions.

    I currently have a Directv dish on my roof and an older mast that was used for a previous dish, about 6ft from the Directv dish. I am going to use the older mast to mount my antenna, because it is secure, and because I don't want to drill any more holes in my roof. It would seem simple to just follow the coax from the directv dish and use that ground and point of entry to the house. But since it goes to the opposite side of the house into my garage, and splits to multiple rooms of the house from there, it is not practical. I would probably need 80 more feet of coax to get the antenna signal to the main television.

    My goal is to pick up some channels that are not considered "local" by directv. I really only need the signal to my main TV, which is only about 30ft maximum from the antenna... plus there is an old point of entry right there that I would use. This is where I put the 8ft grounding rod.

    OK, too much info! :-)

    So if I ground the antenna (via coax) and mast (via outside wire attached to coax) to a coax grounding block, and that block is grounded to the grounding rod buried directly below the point of entry... I should be good for lightning strikes (or, as good as one could hope to be!). Is that right? It is very much the "path of least resistance" to the ground.

    So now my goal is to comply with code, and attach the new grounding rod to the house ground. Im not sure exactly why this needs to be done, but if it is code, there must be good reason. I followed the directv dish coax and see that they used a grounding block at their point of entry, which is attached to the house's main ground.

    So after all of that, here is my follow up question...

    Do I need to run a separate wire from the new ground rod all the way around my house, digging a trench for condiut and all that goes with it... or... would it be acceptable to run a 6ft wire from the antenna mast to the directv dish at their ground points? This would technically connect the grounding rod to the house's main ground, albeit through the two masts.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #5

    Aug 14, 2010, 05:31 PM

    I'm confused.

    Quote Originally Posted by op
    I followed the directv dish coax and see that they used a grounding block at their point of entry, which is attached to the house's main ground.
    This MUST be done. It really doesn't have to be done at the point of entry. It can be done within a few feet from entering the structure or it could be done at the mast.

    What this does is make all power, telephone, plumbing, electrical to all have the same reference. If the coax received a hit, it travels to the building's reference and doesn't disturb it relative to everything else.

    Antenna's don't get grounded. They would not work if they were. The BALUN transformer will isolate the coax ground from the antenna.

    The MAST get's bonded.

    Say a power line fell on the mast. That's a good reason to be bonded to the building electrical system. In many cases it may not be possible.

    The mast getting bonded to a ground rod would protect against a lightning strike. It doesn't protect against one side of the house (the ground you walk on) to be at the same potential as the other side of the house (ground you walk on).

    Yes, this happens during thunderstorms. If the mast was bonded it would not cause you grief.

    With your direct TV system up there, I think you would want to have that connected to the same ground as the house.

    Your house should have a ground rod and have he plumbing system grounded, but older houses do not. Water systems would be grounded within a few feet of entry, so if the wire had to run 40' in the basement it would.

    The whole idea is everything must reference one point. There can be multiple ground rods. I think they need to be at least 6' apart and connected with a wire with no splices. Water pipes must be used too if present.
    Rover88's Avatar
    Rover88 Posts: 68, Reputation: 14
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    #6

    Aug 15, 2010, 08:43 AM
    I agree with both TK and KISS on this, but will add my professional $0.02. Buy the extra 80' of coax and do the job right. Run the additional length of ground wire, and do the job right. I, too, prefer compression fittings. I also prefer solid copper core/copper braid coax. Since this is just for an antennae, I think quad-shield may be overkill, since it won't need to pass the frequencies that satellite would. Also, from experience, I'd review the satellite tech's installation, as they are known within the low-voltage industry to sometimes take shortcuts. BE SURE to use RG6 (not RG59).
    Bill

    KISS: Thanks for the link to DX Engineering. Looks like they have some interesting stuff.

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