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motor supply conductors

Discussion in 'Electrical Engineering' started by A C, Nov 24, 2005.

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  1. A C

    A C Guest

    I have a cabinet shop,the two motors in question are 3hp 230v 1ph
    17fla.Ive read
    the posts about 30A bkr on a 12AWG THHN.
    Does that apply also if my branch circuit is
    romax?My circuits are dedicated home runs,
    one motor for each.My new thickness planer
    already has a #12 cord but no male end,I will
    be putting receptacles on the wall for both motors.Will they only need
    to be 20A rated
    as well? So my plan is to have 25A bkr #12
    romax to a 20A recept,then a 20A cord cap
    through the supplied #12 cord to motor
    starter.Thankyou .
  2. SQLit

    SQLit Guest

    25 amp breaker means a #10 conductor minimum
    17 amps on a #12 might work

    Not enough information for a good analysis.

    Find a copy of the NEC at your library and read the parts about circuit
  3. ehsjr

    ehsjr Guest

    You gain nothing by using #12 and violating the code
    in the process. Use #10 with a 30 amp breaker. The few
    bucks extra for the #10 is well worth it.
  4. operator jay

    operator jay Guest

    Is 30A (or 25A) a large enough breaker to start the motors? You should use
    info from the manufacturer where available, sometimes they recommend a
    breaker size or give a MOCP (max over current protection) value. I think
    the general rule is to have a breaker that's up to 250% of the FLA, e.g. 40A
    in your case. Admittedly that's in Canada. Probably you can use wiring
    smaller than the breaker for motor loads in general, but I think 17FLA is
    too much for #12. 80% of #12's 20A rating would limit you to 16A. I'm not
    sure if you can use a receptacle rated lower than the breaker size. If
    that's not allowed, you may have to use wiring and receptacle rated
    equivalent to the breaker.

  5. operator jay

    operator jay Guest

    You'd think the Ampacity would be higher here, where it's so very much
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