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Dish far from house ground

Discussion in 'DIRECTV Installation/MDU Discussion' started by Neurorad, Oct 18, 2012.

  1. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    I've spent a lot of time reading about 'proper' satellite dish grounding. The NEC seems to be pretty specific, but not specific enough.

    I'm planning a new install, replacing Comcast cable. I've spent a lot of time running cables in my house, for LAN and distributed audio, and I've done my best to stay 'within code'.

    I could do this install myself, but I don't have the time. I really want to get it done.

    It seems most subcontracted DirecTV installers try to ground 'properly,' but aren't aware of the NEC rules - it's not part of the training, and it's not clear in the installation guides.

    Where I want the dish placed is far from the service entrance, and whole-house ground, at the house back corner. The installer will want to place the dish at the front of the house, near the service entrance, because that is the easiest place - and near the service entrance.

    I've researched grounding fairly extensively. This graphic gem from Mike Holt helps (link fixed):

    www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/GroundingSatelliteDishandLead-InCables~20020303.htm

    Bottom line - what wire/cable can I run from the dish to the service entrance for grounding?

    Looks like a 17 AWG copper clad steel messenger wire would suffice, for both mast and coax, according to the NEC guidelines and Mike Holt. Can people confirm? I've read of the need for a 10 AWG copper wire, for coax grounding.

    (Water main is buried outside and behind drywall inside, not an option.)

    Thanks so much.
     
  2. CopyCat

    CopyCat DIRECTV A-Team

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    South Carolina
    I can only tell you what the installer did for me. Our dish is in the back of the house and the electric meter in the front of the house. The house is raised on pilings so there was no digging except to get to the electric meter ground rod.
    He installed a DirecTV SWM LNB and attached the ground wire in the RG6 to the dish and ran 1 double coax back to the electrical meter and attached it to a grounding device and ran #8 copper to the meter ground rod using a new clamp. With the SWM LNB he said the signal would be fine and it is with 95 or better on the various sats. One coax from the LNB is attached to one end of the grounding device and the second coax attached to the other end of the grounding device back to an existing coax which goes up two stories into the smart house junction box where he installed the power supply for the LNB and a splitter with 8 connections, one used for the power supply and the others (6) to 3 DVRs. The spare is capped with a 75ohm terminator. Most professional install I have experienced.

    I forgot to add the dual coax had a ground wire chaser in it, that was tied directly to the ground rod and dish also.
     
  3. Diana C

    Diana C Hall Of Fame DBSTalk Club

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    The NEC correct way would be to ground the dish via it's own ground rod close to the dish and then bond that ground to the service ground. The local ground provides the path to ground for lightning and bonding it to the service ground prevents differences in ground potential between the coax and electrical outlet (important since the receivers do not have grounded plugs). The dish itself and the coax should be attached to the local rod via at least #10 wire. The wire that connects the local rod to the main service ground can be lighter gauge.
     
  4. veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    Bonding two ground rods/points is done with large gauge.
     
  5. Diana C

    Diana C Hall Of Fame DBSTalk Club

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    ^^^^^^^^^^
    What he said! :)
     
  6. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    Thanks for sharing that info.

    Diana, I think the 2nd rod would be required to be bonded to the electrical service electrode using AWG 6 or AWG 10 copper, quite a distance for me.

    I think that unless I can take care of the ground myself, the installer will insist on positioning the dish near the service entrance, at the front of the house in plain sight (as he should, for 'proper' grounding).

    It's difficult to research this subject online, as the NEC requirements have changed over the last 10 years, and what is rec'd in 1 post 8 years ago doesn't seem to fly now.
     
  7. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    Because my questions are based on NEC requirements, maybe I should ask at the Mike Holt forums, too.
     
  8. harsh

    harsh Beware the Attack Basset

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    Salem, OR
    While this part of what you say is true, I'll bet you won't see it done that way if the dish is more than a few feet from the service entrance. Most dishes won't even be earth grounded.

    6ga wire is around $.75/foot and is what is required for creating a bonding point. You cannot use lighter gauge wire and be within code.
     
  9. veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    This is basically what's needed to bond the two ground rods.
     
  10. harsh

    harsh Beware the Attack Basset

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    I think you need to stop trying to second guess the installer. Even if you provide for everything, they're probably going to do it the way that their employer demands.
     
  11. veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    If the new ground rod is in place and bonded, the installer will use it.
     
  12. harsh

    harsh Beware the Attack Basset

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    That's a pretty stiff price to pay to get your way.
     
  13. veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    Grounding is like insurance.
    What it's worth depends on how much you want.
     
  14. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    Absolutely, agreed 100%! Not second guessing at all. Haven't met the installer, haven't placed the initial order yet. ;)

    I'd like to do what I can to avoid the 2nd ground rod, bonded with 150' of 6 awg copper.

    I know it's relatively important to ground the dish to reduce static electricity, and important to ground because of lightning. The static I could take care of by attaching to any house ground. If my dish is hit by lightning, then I'd like to have a good connection to house ground. But in reality, nothing would diminish a direct lightning strike. And unlike cable TV and mains power, I'm not going to get surges from the dish from nearby strikes.

    I guess that's why 90% of satellite dishes - improperly grounded - rarely have problems from that improper grounding. Small dishes, without a tall mast, don't get hit. And for those that do, proper grounding won't do anything.

    So, what cable would I run from the ADU to the house ground, 100 feet away? That Mike Holt graphic linked above

    www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/GroundingSatelliteDishandLead-InCables~20020303.htm

    says 17 AWG copper clad steel (messenger wire) is adequate. How can that be? Good for static electricity reduction, but wouldn't do anything for a lightning strike. Was that 17 AWG spec added to NEC 810 because of satellite company lobbying?
     
  15. veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    Most of Mike's work relates to the load on the circuit for the size/type of ground.

    17 AWG works fine for static discharge.

    If you are wanting any protection from lightning, you'd better have a ground rod VERY CLOSE.

    Two separate ground rods can have different ground potential due to the earth they're driven into.
    Bonding is done to equalize this.
    Using a small gauge conductor becomes a "fusable link" during a lightning discharge, which may not be what you want as it fails.
     
  16. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    I think I need to find where my water main enters the house.

    From my research, I think I can run the 17 AWG copper clad steel messenger wire from the Antenna Discharge Unit to the water main (within 5 feet of the house entrance), if I can find it. Keeping the cable straight would help with surge/strike conduction to the grounded pipe (as if a direct strike wouldn't take out the corner of my house).

    Any thoughts? Would the installer go for this?
     
  17. veryoldschool

    veryoldschool Lifetime Achiever DBSTalk Club

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    At this point, you're selecting the amount of "insurance" you want, and I don't sell insurance, so I'll leave it to you and the installer.
     
  18. harsh

    harsh Beware the Attack Basset

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    Twice you've declared what the installer wants to do. That's the definition of second guessing (determining what they are going to do on their behalf -- as their second).

    Most installers are well versed in what is required by code, DIRECTV and their employer. In my state, they are also expected to have Low Voltage Electrical licenses as well that further drives home the responsibilities as well as practical and safe ways of doing things.

    Installers also have to give strong consideration to where the receivers are going to be located because there are some decided limitations to how much cable you can run without having to make special ($$$) provisions.

    It is like the old addage: Fast, Good (correct) or Cheap: pick any two. [​IMG]
     
  19. west99999

    west99999 Icon

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    Doesnt the NEC code say if you drive a seperate ground rod that it has to be back bonded every 20 feet with #6 and back to the main house ground? I recall seeing this I will look when I have time if nobody else has it right on hand.
     
  20. Jodean

    Jodean Icon

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    sounds to me like the run is way too far to that dish if the ground will 150', no one will install a 150' run to the dish either, then split it all up to rest of the house without amps or other equipment.

    I guess if you NEED it your way pay out the $1000 or just let them do the free install where everything will work properly and no need for amps or trenching electrical services.
     

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