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  • Shared neutral

    I am not a fan of shared neutrals. My house has a few that use the same neutral between two opposite poles. Even so, I try to rewire the shared neutrals out when I get an excuse.

    My question involves a newfangled combination overhead light fixture/vent fan that I'm putting in my current renovation project, the laundry room. I want to wire this so that the fan and the light are controlled by separate wall switches. That way, I can leave the fan running and turn the lights off. My plan is to run 14-3w/g to the fan/light, sharing the neutral between fan and light but hooking red and black wires to different single pole switches, and remarking the red wire to black. The same hot will feed both switches. I don't see any safety issue with this (enlighten me if I'm wrong) since the fixture can also be wired to have both functions controlled by a one single pole switch. My question is, is this ok per NEC, since the feed to each switch is on the same pole? In this case I like using the 14-3 since I end up with one less neutral and one less ground at both the switch and the fixture compared to running two 14-2's.

  • #2
    Re: Shared neutral

    That's how it's done.

    Shared neutrals as most speak about them is when you are using a neutral for 2 different circuits. In your case both the fan and the light are on the same circuit.

    Shared neutrals in the normal context are still acceptable but are becoming increasingly unpractical in residential wiring as more stringent AFCI requirements are put in place. AFCI's don't work with shared neutrals.

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    • #3
      Re: Shared neutral

      Originally posted by Andy_M View Post
      I am not a fan of shared neutrals. My house has a few that use the same neutral between two opposite poles. Even so, I try to rewire the shared neutrals out when I get an excuse.
      OK, this is your prerogative. I personally think it is silly though. Boy is right though, the few two-pole AFCI's that were available are now not. This sucks as there are many valid and good reasons to run shared neutral circuits as home runs.





      Your plan sounds pretty typical to me. One thought though....
      Originally posted by Andy_M View Post
      My plan is to run 14-3w/g to the fan/light, sharing the neutral between fan and light but hooking red and black wires to different single pole switches, and remarking the red wire to black
      Now WHY in the world would you do that????

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      • #4
        Re: Shared neutral

        Thanks for your comments!

        Originally posted by Speedy Petey View Post
        OK, this is your prerogative. I personally think it is silly though. Boy is right though, the few two-pole AFCI's that were available are now not. This sucks as there are many valid and good reasons to run shared neutral circuits as home runs.
        There are two reasons why I don't like shared neutrals. The first is the AFCI issue. I can't use AFCIs in my house where required under current code because of the shared neutral wiring. I understand that I am not required to update for AFCI on an older home, but prefer to do so when I'm working on the wiring for other reasons.

        The second reason I am not a shared neutral fan is that I think it invites a problem. Someone reshuffling breakers to open up a slot in the main panel may well end up wrongly placing both hot legs of the shared circuit on the same pole. This potentially overloads the single neutral. Now, that's not a problem if only a pro touches the panel but we all know that such is not always the case.

        Originally posted by Speedy Petey View Post
        Your plan sounds pretty typical to me. One thought though....
        Now WHY in the world would you do that????
        The only reason is so that someone looking at that 14-3 in the future would see very clearly that both were on the same pole. It takes about ten seconds to do. But yes it is probably not really necessary.
        Last edited by Andy_M; 11-06-2010, 01:48 PM.

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        • #5
          Re: Shared neutral

          your really not sharing a neutral . your light/ fan will be on the same circuit. sharing a neutral would be when you use one neutral for two circuits (one neural for two different breakers). for example when you wire a new house you run a 14-3 to a bedroom ceiling fan that has two switches one for the fan and one for the light. your 14-3 would be your switch legs. do you already have power in a switch you are going to use. and what do you mean you are going to remark the red to black??? sounds to me like what you want to do is normal

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