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Dish far from house ground

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

  1. P Smith

    P Smith Mr. FixAnything

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    W.Mdtrn Sea
    New install ? Everything will be installed by a tech. If you will think he did grounding wrong, do not sign his work order.
     
  2. westom

    westom Mentor

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    Aug 8, 2009
    If a ground is for static discharge, then a 36 gauge (hair thin) wire would be sufficient. Why is that a 1 gauge wire? Nobody installs a more than quarter inch thick (maybe 80 amp) wire to discharge static. Protection already inside each LNB makes static discharges irrelevant. That 1 gauge wire is for even earthing a direct lightning strike.

    If an ethernet port was damaged, then that is most likely an outgoing path; not the incoming path. Damage on that outgoing path means some other incoming path must exist. If a coax between two buldings was not properly earthed at both buildings, then a lightning strike to one building was a direct strike, incoming on the coax, and outgoing (destructively) to earth via ethernet. Damage is on the outgoing path; not incoming path.

    If an interconnection is not earthed at both buildings, then a lightning strike to one building can be a direct strike incoming to electronics inside the other building. Which electronics are damaged? Which electronics have an outgoing path to earth?

    Earthing appliances does not provide transistor protection. Protection is about earthing a surge current. Not about earthing appliances. Earthing the appliance may simply make that appliance a better and destructive connection to earth.

    Many electricians understand ground as only defined by code. Grounding for surges involves requirements not defined by code. Code addresses human safety. Code does not define transistor safety. Transistor safety requires earthing that exceeds what is required by code. To earth before a surge current gets anywhere near to appliances.

    Apparently coax was not earthed; violated those earthing requirements. Worse, lightning currents were apparently permitted inside that other building. Therefore earthing was also defective over there.
     
  3. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    Just some followup, and closure...

    Installer had no issue using the 8 awg bare copper that I installed from the ODU location to the cold water bond, in the MBa below.

    Dish is mounted on the back of the house, not visible from the street; success.

    Install took about 3 hours total, no real problems. In preparation, I ran RG6 from the attic/ODU location to the wiring closet, and added the 8 AWG bare copper.
     
  4. AntAltMike

    AntAltMike Hall Of Fame

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    I was part of the crew that installed five 4.5 meter Patriot Dishes and 9 Blonder Tongue cut to channel antennas on National Captioning Institutes roof in 1994. We grounded the hell out of everything, but some other contractor installed a small, Ku dish and its lnb polarity switching cable was the path for the lightning damage, and as far as I know, the NEC no longer requires rotor lines to be grounded. Grounding the rotor cables used to be required, back when they were flat and it required BOTH outer conductors to be grounded.
     
  5. AntAltMike

    AntAltMike Hall Of Fame

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    I've long assumed that the reason that mast grounding mandated 8 gauge aluminum, 10 gauge copper or 17 gauge copper clad steel was based on physical ruggedness to best assure that the wire would withstand physical stress over the years.

    most likely, Dan succumbed to finger fatigue.
     
  6. n3ntj

    n3ntj Hall Of Fame

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    If the dish is on the opposite side of the home from your electrical service grounding system, then a separate ground rod in the proximity of the dish (within 6 meters) would be required by the NEC. Then, both ground rods (dish and electrical service) are required to be bonded to each other using at least #6 copper to prevent a possible voltage difference between the two.

    The grounding terminal clamp can not be used for another conductor.. each conductor gets its own grounding terminal clamp, although new construction also requires a shared grounding system with phone, cable, satellite, etc. The terminal strip where the coax from the dish is connected (somewhere near the dish) must also be bonded to the dish's ground rod as well. In my travels I find that most satellite dishes are NOT properly grounded or bonded per NEC requirements and most D* installers I talk to have no idea what grounding, bonding, or NEC even mean.
     
  7. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    Agreed. This is true for ALL cables entering a house (phone, cable, mains, pet fence, landscape lighting), to diminish damage from nearby surges. As the small, wall mount dish does not convey surges from nearby strikes, I'm not too concerned about 'proper' grounding of it. The dish and mast SHOULD be grounded in some form, to reduce static discharge buildup - though it's usually an issue for larger dishes.

    Agreed. 2008 NEC guidelines for new construction mandate the use of an Intersystem Bonding Termination (IBT), a 'common' ground block, for communications systems, grounding conductors, and bonding conductors.

    "The IBT provides a single, easily identifiable, physical termination device to which bonding (grounding) conductors of all other systems are to be connected. No struggle to locate an acceptable bonding location. No need for additional listed hardware to facilitate the connection. The installer simply connects the protection device's bonding (grounding) conductor to the IBT terminal and … DONE!"

    http://www.ashireporter.org/HomeInspection/Articles/NEC-250-94-Bonding-for-Other-Systems/1953

    It will make satellite dish installations easier.

    If I wanted my dish installation to meet code, in my preferred location, at the rear of the house, it would have required a series of grounding rods, I believe 20 feet apart, strung together with 6 AWG copper, connecting the ODU/ADU to the service entrance ground. I think it would have to be buried 24 inches below grade, but not certain.
     
  8. n3ntj

    n3ntj Hall Of Fame

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    Lancaster,...
    Yes to the above, except that a satellite dish MUST also to shed static charge that can accumulate simply from wind blowing across it. That is why the dish itself also needs to be properly grounded (as noted in NEC chapters 810 and 820).
     
  9. Neurorad

    Neurorad Cool Member

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    Nov 22, 2009
    Yes, I did mention that. ;)
     

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