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Thread: Shared Neutrals

  1. #11
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    Quote Originally Posted by ron View Post
    Yes, some vendors call that a Super Neutral.

    http://www.afcweb.com/mc-metal-clad-...sized-neutral/
    Ironically, when I was an apprentice, what they called "super neutral" on that job was a cable with two neutrals. Go figure.

  2. #12
    Join Date
    Apr 2016
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    Tampa, Fl
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    Quote Originally Posted by Fly-Guy5 View Post
    Repeate question I'm sure.
    I'm installing 2 30a 120v circuits for a small Network closet in our office. It will be used for our 2 UPS's in the data rack.
    My question is:
    Can I run 1 #10 neutral along with my 2 #10 hots to feed the circuits or do I need 2 neutrals?
    If I read it correctly I only need 1 neutral.

    http://www.ecmweb.com/sites/ecmweb.c...5ecmCQfig2.gif

    Thanks
    I concur with Ron, electronic equipment can generate harmonics on a shared neutral. Consider upsizing your neutral. NEC permits multi-wire Br. Circuits, however a designer needs to be aware of when and when not to utilize a MWBC.

  3. #13
    Join Date
    Sep 2012
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    NJ
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    1,665
    Quote Originally Posted by Fly-Guy5 View Post
    Repeate question I'm sure.
    I'm installing 2 30a 120v circuits for a small Network closet in our office. It will be used for our 2 UPS's in the data rack.
    My question is:
    Can I run 1 #10 neutral along with my 2 #10 hots to feed the circuits or do I need 2 neutrals?
    If I read it correctly I only need 1 neutral.

    http://www.ecmweb.com/sites/ecmweb.c...5ecmCQfig2.gif

    Thanks
    A branch circuit is a portion of a wiring system that extends beyond the final, automatic overcurrent protective device (i.e., fuse or breaker) which qualifies for use as branch-circuit protection, and terminates at the utilization device or outlet (such as a lighting fixture, motor, or heater).

  4. #14
    Join Date
    Dec 2010
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    Tennessee NEC:2008
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    4,224
    Quote Originally Posted by mstrlucky74 View Post
    A branch circuit is a portion of a wiring system that extends beyond the final, automatic overcurrent protective device (i.e., fuse or breaker) which qualifies for use as branch-circuit protection, and terminates at the utilization device or outlet (such as a lighting fixture, motor, or heater).
    What does this have to do with the OP's question?
    If you aim at nothing, you will hit it every time!

  5. #15
    Join Date
    Oct 2013
    Location
    newburgh,ny
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    416

    Split voltage

    One thing to remember, if you share your neutral and it opens then your voltage will divide the 240 Volts between the loads depending on their resistance. In other words magic smoke time, something you don't want.
    A cowboy may get thrown , but they always get up and walk forward.

  6. #16
    Join Date
    Apr 2016
    Location
    Tampa, Fl
    Posts
    140
    Quote Originally Posted by Fly-Guy5 View Post
    Repeate question I'm sure.
    I'm installing 2 30a 120v circuits for a small Network closet in our office. It will be used for our 2 UPS's in the data rack.
    My question is:
    Can I run 1 #10 neutral along with my 2 #10 hots to feed the circuits or do I need 2 neutrals?
    If I read it correctly I only need 1 neutral.

    http://www.ecmweb.com/sites/ecmweb.c...5ecmCQfig2.gif

    Thanks
    Don't forget the current on the shared neutral of 2 phases of a 3 phase 208/120V Y system does not cancel each other. In fact the current is the sum of the current draw on each of the two phases.
    Last edited by GoldDigger; 10-23-17 at 09:33 PM. Reason: Fixed QUOTE tag

  7. #17
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
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    18,374
    Quote Originally Posted by Unbridled View Post
    Don't forget the current on the shared neutral of 2 phases of a 3 phase 208/120V Y system does not cancel each other. In fact the current is the sum of the current draw on each of the two phases.
    Not really.
    It is still the phasor (~vector) sum of the two currents. If current of magnitude I flows in both hots with identical power factor, the magnitude of the neutral current is also I, not 2I

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