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Thread: Nec 2014 compliant?

  1. #1
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    Nec 2014 compliant?

    Attached sketch shows service entrance conductors going into trough. In the trough has ground bar which has supply side bonding jumper to trough enclosure and one grounding electrode conductor going to underground metal water pipe and other is a bonding jumper going to ground rods from the ground bar. The ground bar then has supply side bonding jumper and neutral going to each service disconnects as shown.

    Question is does the attached sketch comply per Nec 2014 Articles 250.64(D)(3) and 250.53(D)(2)?

    Thank you for code expert input



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    Last edited by hhsting; 05-19-19 at 09:05 PM.

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    I see absolutely nothing wrong there. The wire to the rods is another GEC.

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    It looks like you have a neutral from your trough and then another ground wire going to the same block in the disconnects, not allowed and unnecessary. That would be paralleled conductors with objectionable current on your bonding wire.
    Loose the bonding wire to the disconnects as you can use the bonding screw that comes with the disconnect to bond it’s metal case to the grounded conductor block within it. Also you may need to use bonding bushings on one end of the nipples between the trough and disconnect if they are metallic.

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    I agree with steve, didn't notice the redundant ssbj.

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    Is that SE in thr trough using tap rules?

    ~RJ~

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    Quote Originally Posted by romex jockey View Post
    Is that SE in thr trough using tap rules?

    ~RJ~
    Service entrance conductors are tapped but tap rules dont apply to service entrance conductors no?
    Last edited by hhsting; 05-20-19 at 08:41 AM.

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    250.64(D)(3) requires a grounding electrode conductor (one) but two are shown. However, 250.53(D)(2) says supplemental electrode req for underground metal water pipe bonded to grounding electrode conductor. Would all the above make sketch non compliant to code?

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    See 250.64(F)(2). It's a little debatable if this supersedes the 'A grounding electrode conductor..." in 250.64(D)(3), but since the GECs all go to a common point and don't create any parallel paths (besides earth), that would be a really ticky-tack argument.

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    Quote Originally Posted by mopowr steve View Post
    It looks like you have a neutral from your trough and then another ground wire going to the same block in the disconnects, not allowed and unnecessary. That would be paralleled conductors with objectionable current on your bonding wire.
    Loose the bonding wire to the disconnects as you can use the bonding screw that comes with the disconnect to bond it’s metal case to the grounded conductor block within it. Also you may need to use bonding bushings on one end of the nipples between the trough and disconnect if they are metallic.
    Not sure exactly what he has there, the details mostly involve the grounded conductors, but am assuming all service conductors enter the trough, run to service disconnects than back to trough - can't put line and load side conductors of service disconnect in same raceway - but can be in the same trough. Enclosures containing service conductors are supposed to be bonded to the grounded conductor (can be via SSBJ's).

    If the service disconnects were top feed and he put similar ground bar in the trough, but only landed GEC's and/or EGC's on it - still have parallel paths for grounded conductor current to flow, but NEC doesn't necessarily see that as objectionable current paths.

    Looks like maybe he has line and load side grounded conductors ran from the "ground bar" in trough to each disconnect - kind of redundant but not necessarily any code violation. Presuming actual grounded conductors to outgoing feeders also comes off the "ground bar" in the trough. If so all that would be needed to disconnects is a conductor sized per 250.66, they would have no load on them other than "stray currents" that would not be considered objectionable. Good design still may try to eliminate that possibility though.
    Last edited by kwired; 05-20-19 at 02:03 PM.
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