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Thread: Metal to metal to metal

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    Metal to metal to metal

    Warehouse - crude mezzanine. Switch boxes secured to metal bracket secured to shelving. Light fixtures also secured with metal bolts to floor the metal mezzanine. I just do not have a warm and fuzzy feeling about this with respect to bonding and grounding. Any thoughts would be appreciated.
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    Tony Shupenko, PE

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    IMO the issue is the lack of support and fastening of the boxes, raceways, and cables.
    Rob

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    All responses based on the 2014 NEC unless otherwise noted

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    As long as anything attached that is likely to energize the metal is properly grounded, so is the metal itself.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

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    I would be leaning more towards the "Subject to physical Damage" concern.


    JAP>

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    Quote Originally Posted by infinity View Post
    IMO the issue is the lack of support and fastening of the boxes, raceways, and cables.
    Hard to tell... overall mezzanine is sort of makeshift and caused a host of structural problems...
    Tony Shupenko, PE

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    Are those open KO's on the switch boxes? I'd be concerned about curious fingers.

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    The box in the bottom of the picture left of the post has attachment issues too. Is that EMT in a offset nipple in the top opening?
    John, Chair City, NC
    Technology: Mans best efforts to make things as good as they used to be

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    Quote Originally Posted by tonype View Post
    Warehouse - crude mezzanine. Switch boxes secured to metal bracket secured to shelving. Light fixtures also secured with metal bolts to floor the metal mezzanine. I just do not have a warm and fuzzy feeling about this with respect to bonding and grounding. Any thoughts would be appreciated.
    Others have pointed out some other issues, but when it comes to metal to metal to metal - that just increase EGC effectiveness. Your wiring methods should still have a stand alone EGC, even if it is a metal raceway itself as the EGC. All that extra metal framing just gives alternate paths for ground faults should you have a failure in an EGC. You do not in any case want improper bonds to a "grounded" current carrying conductor - that leads to stray currents in non desired current carrying paths during normal operation.
    I live for today, I'm just a day behind.

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    Looks like the switches were in an existing wall that someone removed and just jury rigged the rest.

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