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Thread: Neutrals, connecting all branch circuits neutrals together

  1. #1
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    Neutrals, connecting all branch circuits neutrals together

    I have an electrician in my dept. working on another shift that does some work that I feel is un acceptable. On a multiple wire 120 volt branch circuit, he ties all of the neutrals together under one nut. And he never grounds the box. I have a problem with tieing all of the neutrals together. If you lock out the circuit you are working on downstream from the first junction box and the other circuit in the run is still live. Is there not potential for injury if a fan or other device is plugged into the circuit that is live and carrying voltage back to the neutral on the circuit you are working on. I can't find a code that says in black and white not to do this. He is a person that has to be proven wrong to get him to do things differently. Need some help.

    Allen

  2. #2
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    What he has done is put all of the neutrals in parallel creating parallel conductors. The minimum size parallel conductors permitted is #1/0. Look at 310.4.
    Rob

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    All responses based on the 2011 NEC unless otherwise noted

  3. #3
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    I don’t quite understand the question. A multi-wire branch circuit uses a single neutral conductor from the panel, run with the two (or three) phase conductors, to supply a number of loads. At some point at or near each load, the load’s neutral wire will have to connect to the branch circuit’s one and only neutral wire. That is not a parallel connection, since there is only one wire going all the way back to the panel.

    Can you clarify your description? At what point are these neutrals being tied together? Or are you talking about tying neutral conductors to equipment grounding conductors?
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  4. #4
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    Quote Originally Posted by OldYeller
    I have an electrician in my dept. working on another shift that does some work that I feel is un acceptable. On a multiple wire 120 volt branch circuit, he ties all of the neutrals together under one nut. And he never grounds the box. I have a problem with tieing all of the neutrals together. If you lock out the circuit you are working on downstream from the first junction box and the other circuit in the run is still live. Is there not potential for injury if a fan or other device is plugged into the circuit that is live and carrying voltage back to the neutral on the circuit you are working on. I can't find a code that says in black and white not to do this. He is a person that has to be proven wrong to get him to do things differently. Need some help.

    Allen
    I don't have a problem with tying multiple neutrals together in a junction box and running back a single, properly sized neutral, if that is what you are describing.

    Normally when you lockout a 120V circuit the neutral is not disconnected anyway. it is not required that a grounded conductor be disconnected by the disconnecting means.
    Bob

  5. #5
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    I think maybe he's talking about more than one circuit.

    2 multi wire circuits run in the same conduit would have two neutrals.
    I don't think those two should be tied together. I think they should be identified some how to keep them with their respective circuits.

  6. #6
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    Quote Originally Posted by realolman
    I think maybe he's talking about more than one circuit.

    2 multi wire circuits run in the same conduit would have two neutrals.
    I don't think those two should be tied together. I think they should be identified some how to keep them with their respective circuits.

    That is what I assumed, maybe a conduit with several MWBC's. I have seen an electrician take a bunch of neutrals from MWBC's and splice them all together in a homerun box.
    Rob

    Chief Moderator

    All responses based on the 2011 NEC unless otherwise noted

  7. #7
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    Quote Originally Posted by realolman
    I think maybe he's talking about more than one circuit.

    2 multi wire circuits run in the same conduit would have two neutrals.
    I don't think those two should be tied together. I think they should be identified some how to keep them with their respective circuits.
    Why? It is the same point electrically back at the neutral bar.
    Bob

  8. #8
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    actually, I'm not sure why. Maybe it's not necessary. It just seems like something you ought to do.

    Are you saying it would be ok to run 3 or 4 20 a. multiwire circuits in the same conduit and only have one #12 neutral wire? I suppose the wire could handle it allright, it just seems to me if you de-energize the phase you should de energize the neutral also.

    I have run separate neutrals to motor starters in a cabinet if they are fed from different control power fuses, just so you can change them ( the starters ) without interfering with the other starters.

    maybe you don't have to ...I don't know.

    Old Yeller also mentioned grounding the box. If you were to run an EGC in conduit, are you supposed to connect it to every junction box as well?
    Last edited by realolman; 11-10-06 at 06:08 PM.

  9. #9
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    Bob,

    If you are thinking about a "common neutral" conductor, then I agree, there is no problem.

    However my hunch is that the original poster is describing a situation in which multiple circuits, with multiple separate neutrals, have all the neutrals tied together in a junction box. In this case the electrician would have created 'conductors in parallel', connected electrically at the same point in the panel and at the wire nut. 310.4 makes this perfectly reasonable.... if the conductors are size 1/0 or larger

    (Aside: common neutral circuits have been debated to great length in other threads, and I don't intend to re-open this debate here. As a summary: common neutral circuits have a grounded conductor that is sized for the maximum unbalanced load of all the associated ungrounded conductors. They are explicitly described in 225.7(B) for _outside_ branch circuits and feeders for lighting, and common neutral feeders are described and limited in 215.4. Common neutral circuits are _not_ mentioned in article 210, either to permit or to prohibit them. Multiwire circuits could be considered a special case of common neutral circuits. Some would argue that since multiwire circuits are permitted, this is an implicit prohibition against other common neutral circuits, others would argue that since common neutral circuits are not prohibited, then they are allowed. Search for the other thread for more details.)

    -Jon

  10. #10
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    Quote Originally Posted by petersonra
    Why? It is the same point electrically back at the neutral bar.
    Other than being a violation of 310.4 I can't think of any real issues that will become of it.

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