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Thread: GEC for 3800A Service

  1. #1
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    GEC for 3800A Service

    Hello everyone,

    We are installing a new 120/208v 3800A service in a commercial building. There are no drawings or specs to go off of, more of a design build job.

    The switchgear is made up of 3 sections of busbar, one service disconnect switch and two distribution panels.

    We are using two of the sections of gear to land our wire. Each section will have 8 parallel feeds of 500kcmil copper conductors which makes 16 conductors per phase. So essentially 2, 3800A feeds from two utility vaults. One vault to one section, the second vault to another.

    I am being told that we need to bring 2 GECs to the water pipe and 2 supplemental GECs to building steel (a set for each section).

    My question is, since the sections share the same bus, A B C N and G, do we need to do this or could we just bring one GEC to the main water pipe and one supplemental GEC to building steel?

    Any help is appreciated, thank you.

  2. #2
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    New Jersey
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    The GEC's will go to the single service disconnect, one for each electrode if you run two separate GEC's. #3/0 copper is the largest required for the water pipe or building steel.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  3. #3
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    Great, thank you.

  4. #4
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    Quote Originally Posted by sparky315 View Post
    The switchgear is made up of 3 sections of busbar, one service disconnect switch and two distribution panels.

    We are using two of the sections of gear to land our wire. Each section will have 8 parallel feeds of 500kcmil copper conductors which makes 16 conductors per phase. So essentially 2, 3800A feeds from two utility vaults. One vault to one section, the second vault to another.
    Am I reading this correctly: one of the service feeders lands on busbar in a distribution section?

  5. #5
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    The only way this makes sense to me is that the bus bar sections are just there as a place to land the wires from the utility. They then feed the disconnect switch which feeds the distribution panels. I don't know why you need 16 500 KCM wires though for a 3800 amp service.
    Bob

  6. #6
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    So essentially 2, 3800A feeds from two utility vaults. One vault to one section, the second vault to another.
    Can you elaborate on that? Same POCO transformer? Paralleled service feed?

  7. #7
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    Quote Originally Posted by petersonra View Post
    The only way this makes sense to me is that the bus bar sections are just there as a place to land the wires from the utility. They then feed the disconnect switch which feeds the distribution panels. I don't know why you need 16 500 KCM wires though for a 3800 amp service.
    Still, doesn't make sense. 8 sets of 500's are only good for 3040A (double-ended supply) and 16 sets are absolute overkill for a 3800A service.
    I will have achieved my life's goal if I die with a smile on my face.

  8. #8
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    Even if it is Aluminum 16 sets seems like Overkill
    Bob

  9. #9
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    10 sets of copper 500 kcm would make sense for a 3800 Amp service.

    It would kind of make sense that they picked an odd service size to make do with the most economical wire solution but 16 sets just does not make any sense to me at all.
    Bob

  10. #10
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    Quote Originally Posted by petersonra View Post
    10 sets of copper 500 kcm would make sense for a 3800 Amp service.

    It would kind of make sense that they picked an odd service size to make do with the most economical wire solution but 16 sets just does not make any sense to me at all.
    Aluminum and voltage drop?

    I will have achieved my life's goal if I die with a smile on my face.

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