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Thread: Bonding isolated rigid pipe section

  1. #1
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    Bonding isolated rigid pipe section

    I'm running about 30 feet of rigid conduit underground. Both ends turn up out of the ground and transition to PVC, i.e. the rigid is not bonded to any other part of the system. I think I'm required to bond it. One end is a few inches away from a ground rod. Is it compliant if I put an exterior clamp on the pipe and bond it to the ground rod? The ground rod is a supplemental for a subpanel. The conduit is carrying the feeder for that same subpanel.

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    250.86 exception 3 would allow a metal elbow not bonded to EGC if buried below 18 deep, but that is only thing mentioned there is the elbow.
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    Quote Originally Posted by kwired View Post
    250.86 exception 3 would allow a metal elbow not bonded to EGC if buried below 18 deep, but that is only thing mentioned there is the elbow.
    Based on my reading of 250.86 I'm required to connect the pipe to the Equipment Grounding Conductor. I've connected it to the Grounding Electrode Conductor (which is about 5 feet from the subpanel ground buss). Am I compliant? I don't know how I would connect to the EGC since the metal pipe does not terminate in a box where I can attach a grounding bushing.

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    Quote Originally Posted by Coppersmith View Post
    Based on my reading of 250.86 I'm required to connect the pipe to the Equipment Grounding Conductor. I've connected it to the Grounding Electrode Conductor (which is about 5 feet from the subpanel ground buss). Am I compliant? I don't know how I would connect to the EGC since the metal pipe does not terminate in a box where I can attach a grounding bushing.
    It must be bonded to the EGC for the circuit that is in the conduit.
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

  5. #5
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    Quote Originally Posted by Coppersmith View Post
    I don't know how I would connect to the EGC since the metal pipe does not terminate in a box where I can attach a grounding bushing.
    Put in a rigid C-condulet at the rigid-PVC transition, and bond the EGC to the C-condulet as it passes through?

    Cheers, Wayne

  6. #6
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    Quote Originally Posted by wwhitney View Post
    Put in a rigid C-condulet at the rigid-PVC transition, and bond the EGC to the C-condulet as it passes through?

    Cheers, Wayne
    I'm pretty sure that a condulet or a box is supposed to remain accessible. He wants to bury the whole thing.

    @Coppersmith

    Why not just do the whole thing with RMC or with PVC?

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    Quote Originally Posted by jaggedben View Post
    I'm pretty sure that a condulet or a box is supposed to remain accessible. He wants to bury the whole thing.
    I'm pretty sure he's using RMC to keep the required cover down to 6", so with an RMC elbow, if the end of the elbow isn't above grade, a short RMC nipple would get it above grade.

    Cheers, Wayne

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    Quote Originally Posted by wwhitney View Post
    I'm pretty sure he's using RMC to keep the required cover down to 6", so with an RMC elbow, if the end of the elbow isn't above grade, a short RMC nipple would get it above grade.

    Cheers, Wayne
    If that is the reason, the question is still why not run RMC the entire run? Why transition to PVC for the riser out of the ground which is probably a rather insignificant length compared to the rest of the run, unless maybe you need to make some bends out of the ground and don't have equipment to bend the RMC?? 1/2 - 1" can be bent with next size larger EMT hand benders though. Many have at least a 1/2 and 3/4 EMT hand bender.
    I live for today, I'm just a day behind.

  9. #9
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    Quote Originally Posted by jaggedben View Post
    Why not just do the whole thing with RMC or with PVC?
    Quote Originally Posted by wwhitney View Post
    I'm pretty sure he's using RMC to keep the required cover down to 6", so with an RMC elbow, if the end of the elbow isn't above grade, a short RMC nipple would get it above grade.
    Yes, that is the reason. I don't like digging any deeper than I have to. The 90 turns above the grade.

    Quote Originally Posted by kwired View Post
    If that is the reason, the question is still why not run RMC the entire run? Why transition to PVC for the riser out of the ground which is probably a rather insignificant length compared to the rest of the run, unless maybe you need to make some bends out of the ground and don't have equipment to bend the RMC?? 1/2 - 1" can be bent with next size larger EMT hand benders though. Many have at least a 1/2 and 3/4 EMT hand bender.
    1.5" RMC. No I don't have a bender or a threader for that. I could have run the panel end entirely in RMC but it would have been a major hassle going up the wall, to an LB and thru the wall with all rigid. PVC is so much easier, cheaper, and more flexible. 1.5" RMC is $43 a stick. Compression couplings $17 each. I wanted to use IMC but none of the supply houses within 50 miles had it in stock.

    I'll reiterate: How does one attach an EGC to an isolated section of pipe? Am I allowed to run a ground wire outside the pipe and clamp it on?
    Last edited by Coppersmith; 09-15-18 at 10:33 PM.

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    Quote Originally Posted by Coppersmith View Post
    ....I'll reiterate: How does one attach an EGC to an isolated section of pipe? Am I allowed to run a ground wire outside the pipe and clamp it on?
    No. 300.3(B)
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