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MWBC with line-neutral AND line-line loads

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  • kwired
    replied
    Originally posted by jap View Post
    There may not be the need to add subpanel.

    The OP was simply asking if he could do it.

    Heck, for all we know the panel may already be in the garage.

    JAP>
    Exactly, say this is an existing detached garage with just a MWBC supplying it, I'd probably do what OP is asking if the chance of too much load at once isn't very great.

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  • jap
    replied
    There may not be the need to add subpanel.

    The OP was simply asking if he could do it.

    Heck, for all we know the panel may already be in the garage.

    JAP>

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  • ptonsparky
    replied
    Originally posted by Cow View Post
    I would do everything in my power to talk them into a subpanel, rather than hooking a bunch of 120v and 240v receps to the same circuit.
    What will it add for a 4 circuit main lug panel? Maybe $100? Not worth the time thinking about it.

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  • Cow
    replied
    I would do everything in my power to talk them into a subpanel, rather than hooking a bunch of 120v and 240v receps to the same circuit.

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  • rszimm
    replied
    Yeah, so just a typical 2 pole breaker.

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  • LarryFine
    replied
    Originally posted by rszimm View Post
    Why do you say that? It would seem Exception 2 applies here.
    Read the exception again. Only line-to-neutral loads unless protected by a breaker that assures simultaneous opening of all lines.

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  • infinity
    replied
    Originally posted by rszimm View Post
    Why do you say that? It would seem Exception 2 applies here.
    It does when you use a mulit-pole circuit breaker.

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  • rszimm
    replied
    Originally posted by LarryFine View Post
    Now allowed.
    Why do you say that? It would seem Exception 2 applies here.

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  • LarryFine
    replied
    Originally posted by david luchini View Post
    Now allowed.

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  • david luchini
    replied
    Originally posted by dkidd View Post
    210.4(C) Line-to-Neutral Loads. Multiwire branch circuits
    shall supply only line-to-neutral loads.


    Originally posted by rszimm View Post
    2017 NEC. 210.4.C says "MWBC shall supply only line-neutral loads", but exception 2 says "When all ungrounded conductors of the MWBC are opened simultaneously by the branch-circuit overcurrent device".

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  • jap
    replied
    Originally posted by rszimm View Post
    Of course. Great point. OK, so is there anything else in the code that I'm not thinking of that would prevent a mixture of line-line and line-neutral loads on the same MWBC?
    A mixture of line-line and line -neutral loads occur all the time.

    Think of Range or Dryer circuits for example, or, even a 120/240v panel in itself.

    Just be careful what you call the circuit and be mindful of the OCPD installed ahead of the conductors.


    JAP>

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  • 480sparky
    replied
    Even if it's permitted, it sounds like a poor design IMHO.

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  • dkidd
    replied
    210.4(C) Line-to-Neutral Loads. Multiwire branch circuits
    shall supply only line-to-neutral loads.

    Leave a comment:


  • rszimm
    replied
    Of course. Great point. OK, so is there anything else in the code that I'm not thinking of that would prevent a mixture of line-line and line-neutral loads on the same MWBC?

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  • david luchini
    replied
    Originally posted by rszimm View Post
    Given that 210.4.B already requires that all ungrounded conductors be simultaneously disconnected, isn't 210.4.C completely moot/irrelevant?
    Being "disconnected" and being "opened simultaneously by the branch OCD" are different things, so 210.4(C) isn't moot.

    Two or three single pole circuit breakers with a handle tie would accomplish the first but not the second.

    A two pole or three pole circuit breaker would accomplish both.

    Edit: Or what Sierra said

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