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    curtiseggen's Avatar
    curtiseggen Posts: 5, Reputation: 1
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    #1

    Jun 28, 2010, 01:45 PM
    Grounding 2 main panels on 1 meter
    I'm new to this group, but have read several threads and the answers seem well thought out and reasonable. Thanks for this forum!

    I have two, 3-phase, 200A main breaker service entrance panels, each wired (3/0) to dual lugs in a 320A meter can. They are grounded (with #2 cu) as follows:

    Panel A's ground wire runs from a lug on its (bonded) neutral/ground bar to an 8' ground rod.

    Panel B's ground wire runs from a lug on its (bonded) neutral/ground bar to a lug screwed to the metal housing inside of Panel A.

    I asked a local electrician about this, and he said it was okay, but it seems to me that this has introduced multiple points of failure between Panel B and earth.

    My question - is this okay the way it is? And if not, what's the best/proper method?

    Thanks for any suggestions.
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #2

    Jun 28, 2010, 02:26 PM
    To help with possible problems with the words, any chance of getting some photos of both panels and meter?

    Or a diagram?
    curtiseggen's Avatar
    curtiseggen Posts: 5, Reputation: 1
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    #3

    Jun 28, 2010, 03:37 PM
    I chose my words carefully, but it is a rather difficult thing to describe. Let me see if I can upload something to clarify...
    curtiseggen's Avatar
    curtiseggen Posts: 5, Reputation: 1
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    #4

    Jun 28, 2010, 05:24 PM
    Okay, here is a diagram of the situation. I'm wondering if the ground connection for Panel B is okay as built. Thanks!
    curtiseggen's Avatar
    curtiseggen Posts: 5, Reputation: 1
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    #5

    Jun 28, 2010, 05:26 PM
    Trying again for image...
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    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #6

    Jun 29, 2010, 08:20 AM
    It is not the way I would have done it, and I see a possible ground loop in how both grounds get connected at Panel A.

    The meter neutral should be grounded to earth directly, so the system neutral is grounded.

    Then at each panel the neutral is bonded to equipment ground in that panel.
    curtiseggen's Avatar
    curtiseggen Posts: 5, Reputation: 1
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    #7

    Jul 1, 2010, 05:20 PM
    Thanks, tk. Both panel neutral bars are bonded to ground. Panel A goes straight to ground, but Panel B is only grounded through Panel A.

    You say that's not how you'd have done it. Which is why I submitted the question, I guess, it didn't feel right to me either.

    May I ask... how would you have done it?
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