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Grounding of Satellite dish

Discussion in 'Electrical Engineering' started by gary, May 16, 2005.

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  1. gary

    gary Guest

    Last November I had DirecTV install a satellite dish at my house. They
    ran a ground from the dish about 80' to an outside plumbing bib. It is a
    single wire (green insulation) and looks to be about an 8 gage or so. It
    has at least three 90 degree turns in it.

    In the past 2 months I have had two pin hole leaks develop in my cold
    water copper plumbing within 5' of the water bib.

    I am receiving contradictory responses on the alt.construction site as
    to whether this is a permissible grounding situation under the NEC and
    also as to whether this might have caused the problems with the piping.

    I've googled and not found anything directly relating to this issue.

    Can someone provide me the NEC codes for this? Any comments as to the
    potential for the problem being caused by the grounding would be greatly
    appreciated.

    Thank you,
    Gary
     
  2. SQLit

    SQLit Guest

    Do you have the ability to measure current and voltage in small quantities?
    I doubt that the installer used 8 awg.
    I have a DTV dish and they ran the #12 goofy green wire ( all humor
    intended ) to my electrical service riser, right next to the Telco ground.

    It is "possible" that this new connection has created a new path for some
    current/voltage.

    Is your water pipe bonded to your service? Might be where the water comes
    into the house or at the water heater. Has someone installed plastic pipe
    in the water system?

    Might be time to consult with some local professionals
     
  3. Rowbotth

    Rowbotth Guest

    Generally speaking, the purpose of grounding these dishes is to
    dissipate a lightning strike so it doesn't get into your house and melt
    things or start a fire.

    But if they have three 90 degree bends in the thing, it is functionally
    useless. If you have taken a lightning strike, you will see a hole in
    the insulation at the location of one of the 90 degree bends - likely
    the top one, but maybe the lower - I forget whether the greatest
    differential to earth is critical here, or whether the first bend on the
    way to earth potential.

    If your insulation is intact, I'd change it so it ran as straight and as
    direct to your earth connection - and I think I'd put a 10' rod at the
    point where the insulation would go to ground if you dropped it. Also,
    if your insulation is intact it is unlikely that this conductor caused
    your problems with the copper wire plumbing. It may have something to
    do with metallurgy - is there something here maybe that is not copper,
    and the copper may be sacrificing itself to a less noble metal?

    Good luck with solving this one.

    H.
     
  4. John Ray

    John Ray Guest

    You're definitely on the right track here. Install a ground rod as straight
    and near as you can to the dish, then bond that ground rod to the service
    ground electrode. According to NEC you need a #6 between the two, even if
    the equipment grounding conductor for the dish is smaller.

    HTH,
    John
     
  5. SQLit

    SQLit Guest

    9999999999999999snipped9999999999999999999999

    UL96A is the standard for lightning protection. You can install 90 degree
    bends as long as they are of a large radius. (radius is dependant on the
    conductor size). Down leads and conductor for all of the lightning
    protection systems I have installed were braded wire either of copper or
    aluminum not building wire.

    Lightning protection is sacrificial at best. I can will all assurity
    guarantee you that if lightning hits the dish your going to have a LOT more
    problems than just a toasted dish. I worked on a home that was struck in
    the corner. We ended up removing all of the drywall to get at the studs so
    we could pull new wiring. Not one piece of wire survived end to end. There
    was not one electrical device in the home that was plugged in, that
    survived. Electrically it was total devastation.
    There was a UL listed lightning protection system on the roof. There were
    black marks down the house where the conductors were.

    Grounding is not lightning protection.
     
  6. Rowbotth

    Rowbotth Guest

    I beg to disagree. The function of the ground conductor on a satellite
    dish is for lightning protection.

    And a large radius bend on a house? Where did you plan to put the
    conductor - and how many home owners would let you string an ugly green
    cable all over their homes, would ya think?

    I stand by my original comments. Make the conductor straight. Sorry.

    HR
     
  7. gary

    gary Guest

    Tom, the meter is on the utility pole about 140 ft from the house. The
    electric service from the pole to the house is underground and comes up
    through the slab in the garage to a 220 CB box which then goes to a 110
    CB box.
    ie. all 220 is fed from one CB box and all 110 is fed from another about
    15 feet away (also in the garage).

    The dish is mounted to a chimney which is the "middle" (give or take a
    little) of the roof so there is no direct path without crossing the
    roof. It is at least 50 ft from the 220 and 110 boxes I mentioned above.

    Gary
     
  8. gary

    gary Guest

    Thanks Tom,
    Sounds like its time to get a licensed Electrician to look at the entire
    mess. The plumbing problems have already cost me over $1500 in repairs
    for the two pipes. Probably won't get anywhere with DirecTV or the local
    company that installed it, but think I'll try anyway.

    Maybe if I make a big enough noise about it (local "investigative
    reporters" come to mind) they won't be able to continue to get away with it.

    Gary
     
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