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Thread: neutral of a branch circuit be reduced in size

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    neutral of a branch circuit be reduced in size

    We have a 54 KW boiler, 240 single phase that is continuous duty which is 281 amps. Will feed with (2) 300 KCMILL conductors on 300 amp OCPD. There is a small neutral load of less than 3 amps. Can the neutral of a branch circuit be reduced in size from the phase conductors. If so where is it in the NEC?

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    Is there an OCP device at the furnace making this circuit a feeder or is it actually the branch circuit to the furnace ?
    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.

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    If is is a feeder then yes but the neutral cannot be smaller than the required equipment grounding conductor. If it is a branch circuit then IMO, you cannot. So run a feeder to the equipment and use a disconnect with overcurrent protective device and then you are good to go
    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



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    Quote Originally Posted by Dennis Alwon View Post
    If is is a feeder then yes but the neutral cannot be smaller than the required equipment grounding conductor. If it is a branch circuit then IMO, you cannot. So run a feeder to the equipment and use a disconnect with overcurrent protective device and then you are good to go
    What says that the grounded and ungrounded conductors for a branch circuit must be the same size?
    Don, Illinois
    (All code citations are 2017 unless otherwise noted)

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    Quote Originally Posted by don_resqcapt19 View Post
    What says that the grounded and ungrounded conductors for a branch circuit must be the same size?
    Interesting..
    I was heading the same direction as Dennis (I think) in that Feeders (and services) give the allowance for neutral reduction but I fond no such wording in Art 210.
    It appears in the OPs situation, 210.19 would allow a #14.
    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.

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    The problem with a reduced neutral in a two wire branch circuit is 240.4, particularly 240.4(D), the smallest conductor in the circuit will govern the size of the circuit and the OCPD.

    Roger
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