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Thread: 225.30 - is it ok if running 3 branch circuits to a detached garage

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  1. #1
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    225.30 - is it ok if running 3 branch circuits to a detached garage

    Hello All,
    Per 225.30, multiwire branch circuit shall be considered a single circuit. And per Art 100, Definitions, multiwire is a branch circuit that consists of 2 or more hot conductors. So I can run (3) 120V circuits (for example #1, #5, #9) to a garage without having to install a sub-panel?
    Thanks.

  2. #2
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    Do you have three phase power?
    If you go and decide to dance with a gorilla the dance ain't over till the gorilla decides it's over.

  3. #3
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    Not unless you have 3 phase at your house, use a shared noodle for the 3 hots, each hot is on a different phase, and you use a 3P breaker or handle tie 3 SP together.

    Prolly not I assume.

    What you may do is run a single MWBC to a detached structure, which for resi is 2 hots, one from each leg, and a shared neutral. 2P breaker or handle tie needed.
    "Electricity is really just organized lightning." George Carlin


    Derek

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    Quote Originally Posted by fandi View Post
    Hello All,
    Per 225.30, multiwire branch circuit shall be considered a single circuit. And per Art 100, Definitions, multiwire is a branch circuit that consists of 2 or more hot conductors. So I can run (3) 120V circuits (for example #1, #5, #9) to a garage without having to install a sub-panel?
    Thanks.
    You left out the sharing a neutral part. For 1Ø, 120/240 circuits #1-#5-#9 would all require separate neutrals so the answer is no.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  5. #5
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    Quote Originally Posted by infinity View Post
    You left out the sharing a neutral part. For 1Ø, 120/240 circuits #1-#5-#9 would all require separate neutrals so the answer is no.
    1 5 and 9 in a three phase panel will use all three phases - good luck finding appropriate handle tie though.

  6. #6
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    Quote Originally Posted by kwired View Post
    1 5 and 9 in a three phase panel will use all three phases - good luck finding appropriate handle tie though.
    That's true and the reason that I specified single phase.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  7. #7
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    Quote Originally Posted by infinity View Post
    You left out the sharing a neutral part. For 1Ø, 120/240 circuits #1-#5-#9 would all require separate neutrals so the answer is no.
    Thanks Mod. I just install a sub-panel at the garage and then for ground: drive a new rod or tie to the cold water pipe. Is there any separate disconnect required between the main panel and the sub-panel or the main breaker at the sub-panel would suffice?

  8. #8
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    You need a building disconnecting means at the remote building. A main breaker in its sub panel will satisfy that requirement.
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

  9. #9
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    Quote Originally Posted by charlie b View Post
    You need a building disconnecting means at the remote building. A main breaker in its sub panel will satisfy that requirement.
    Thanks, Charlie.

  10. #10
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    Quote Originally Posted by fandi View Post
    . . . per Art 100, Definitions, multiwire is a branch circuit that consists of 2 or more hot conductors.
    I suggest you go back and read that definition more carefully (i.e., I am invoking "Charlie's Rule"). It requires each hot conductor to be on a different phase. In a 120/240V single phase panel, circuits 1, 5, and 9 are all on the same phase (i.e., have zero voltage between them). So no, you can't do that.

    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.

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