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Thread: next higher size???

  1. #1
    Join Date
    May 2013
    Location
    Tujunga, CA
    Posts
    427

    next higher size???

    Hi
    I am supplying a 120' away sub panel l thru a set of #6 thhn, cu in an apartment building.

    Question is,
    can use 70A ocpd for the feeder main ; according to next-larger size rule ?????

    Also,
    70A ocpd for the feeder main; What size copper wires can be used to feed that apartment sub panel. ???????

    Thank you

  2. #2
    Join Date
    Jul 2005
    Location
    Tennessee
    Posts
    15,865
    215.2 requires that your feeder conductor have the amapcity to supply the load so your #6 THHN would be good for a 65 amp loadassuming 75° terminations. If your load does not exceed 65 amps, you are good with a 70 amp overcurrent device.
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

  3. #3
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    36,256
    Quote Originally Posted by augie47 View Post
    215.2 requires that your feeder conductor have the amapcity to supply the load so your #6 THHN would be good for a 65 amp loadassuming 75° terminations. If your load does not exceed 65 amps, you are good with a 70 amp overcurrent device.
    I second that and add that if your feeder is NM cable - you are limited to 60C ampacity.
    I live for today, I'm just a day behind.

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