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-   -   Parallel feeders (https://www.askmehelpdesk.com/showthread.php?t=734423)

  • Feb 15, 2013, 08:31 PM
    Hdtrike
    Parallel feeders
    A 3ph 400amp service using 250 al can you use one conduit or two conduits, 8 wires
  • Feb 15, 2013, 09:12 PM
    Grady White
    Not sure but I think each feeder has to be in it's own conduit.
  • Feb 16, 2013, 05:15 AM
    stanfortyman
    Either.
    One reason to use separate conduits is to get around the higher derating factor.

    I must say, someone doing this installation should not be asking this question on a "Home & Garden" DIY message board. I hope you are just asking for curiosity or education purposes, or that you have someone on the job with more experience than you.
  • Feb 16, 2013, 05:22 AM
    stanfortyman
    Also, if this is a wye 3-phase system 250MCM AL is not good for your service. You'll have 4 current carrying conductors in each conduit so you have to derate to 80%.
    You'll need 350's.

    See NEC 310.15(B)(5)

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