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Thread: Sizing Service Entrance Conductors - 2014 NEC

  1. #1
    Join Date
    Oct 2015
    Location
    Woodland, WA USA
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    3

    Sizing Service Entrance Conductors - 2014 NEC

    I am studying for the code calculations portion of my WA State Residential Administrator's exam (based on 2014 NEC).

    When sizing service entrance conductors for a single family dwelling using either the standard or optional methods, which value of current do I multiply by 83%?

    The calculated load (27600 volt-amps divided by 240 volts = 115 Amps?

    or

    The service rating determined by the next standard breaker size, 125 Amps?

  2. #2
    Join Date
    Jul 2005
    Location
    LA basin, CA
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    1,581
    The conductor is allowed to be sized 83% of the Main breaker.

    ..shall be permitted to have an ampacity not less than 83 percent of the (service or feeder) rating.
    Roger Ramjet NoFixNoPay

  3. #3
    Join Date
    Dec 2006
    Location
    Chapel Hill, NC
    Posts
    32,344
    Ramsy got it... If you have a 200 amp main breaker then the conductors feeding that 200 amp breaker can be sized at 166 amps (200 x .83) or larger.
    They say I shot a man named Gray and took his wife to Italy
    She inherited a million bucks and when she died it came to me
    I can't help it if I'm lucky



  4. #4
    Join Date
    Oct 2015
    Location
    Woodland, WA USA
    Posts
    3
    Thank you both! 😊

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