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Thread: Shielded ground wire.

  1. #1
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    Shielded ground wire.

    Hello all, I'm a new building inspector and want to do my job as best as possible. We have some controversy in regards to the need to bond the shielding at the ground clamp to rod connection. When running two ground rods with shielded grounding wire do you need 2 clamps at the first rod in order to continue the bonding of the shielding material between the two rods or is the contact of the shielding to the wire sufficiently bonded? I apologize in advance if this is a silly question, but being new to this job I want to provide the correct answer to the contractors of the area. Thank you

  2. #2
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    Welcome to the forum.

    Before anyone can answer your question accurately we need to establish a common vocabulary. What is a shielded ground wire and what is it connected to?

    Also check out the sticky in this sub-forum "Grounding and Bonding the big picture".
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

  3. #3
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    Hopefully this picture works. I'm referring to ground wire from the panel to two ground rods, when its stranded it needs mechanical protection via a metal armor or shielding. Maybe I should say armored ground wire?
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  4. #4
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    would this be the appropriate clamp?
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  5. #5
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    I would called that armored. I'd also say that is something I've never seen before, but I think there was a previous discussion about that stuff. 250.64 (E) is the code section that applies.

    The clamp looks compliant to me. Is that armor ferris metal or aluminium? Who says stranded needs to be protected?
    Once in a while you get shown the light
    In the strangest of places if you look at it right. Robert Hunter

  6. #6
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    By the looks of it there seems to be a smaller section to strip or maybe is where connection is to be clamped -- could this be for a lightning protection -- never seen this type of GEC
    CircuitRyder --- Unfortunately not all good ideas are code enforceable.

  7. #7
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    Quote Originally Posted by ActionDave View Post
    I would called that armored. I'd also say that is something I've never seen before, but I think there was a previous discussion about that stuff. 250.64 (E) is the code section that applies.

    The clamp looks compliant to me. Is that armor ferris metal or aluminium? Who says stranded needs to be protected?


    If the armor is ferrous metal (basically steel) then the same physics that leads to the provisions that apply to a ferrous metal raceway will apply and you would need to bond the armor to the GEC at both ends of the run. The fact that the magnetic coupling between turns of the spiral is weak makes it less of a concern, but I would bond it anyway.

    Essentially you have a multi-turn magnetic core wrapped around a wire rather than a multi-turn wire wrapped around a magnetic core.

  8. #8
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    Quote Originally Posted by Inyoinspector View Post
    would this be the appropriate clamp?
    The NEC calls that cable armor. The conductor within it is bare so bonding the armor to the conductor probably won't do much. The ground rod needs to be 8' in contact with the earth.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  9. #9
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    Quote Originally Posted by Inyoinspector View Post
    Hopefully this picture works. I'm referring to ground wire from the panel to two ground rods, when its stranded it needs mechanical protection via a metal armor or shielding. Maybe I should say armored ground wire?
    Yes, armored ground wire and that is the exact clamp for how you have it. I've seen armored around here occasionally in the distant past. Is that a code requirement (addendum to the NEC) where you are? Here we bury the ground rods (pound them all the way below grade. The rod needs to be 8' in contact with the earth as mentioned.) We usually sleeve the GEC from the building in PVC down to the ground rod then bury the conductor between the rods. I would worry about that armor outdoors.

    -Hal

  10. #10
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    Quote Originally Posted by ActionDave View Post
    I would called that armored. I'd also say that is something I've never seen before, but I think there was a previous discussion about that stuff. 250.64 (E) is the code section that applies.

    The clamp looks compliant to me. Is that armor ferris metal or aluminium? Who says stranded needs to be protected?
    Thanks to everyone for the replies. The armor is aluminum and is required here for any stranded ground. We also do 2 rods no closer than 6' apart so there is more than 8' in contact in the ground. No armor is required if its #6 or larger and solid, #8 solid would also need to mechanically protected. (At least according to the building official) Ca has a few extra codes.

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