Multiwire branch circuit

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  • guycox
    Established Member
    • Dec 2003
    • 360
    • Romulak, VA, USA.

    Multiwire branch circuit

    I had some extra circuits run -- the fellow who did the work ran three circuits for me over one piece of Romex -- with a single neutral. He said that it met code but I think he is mistaken. I can see 3 circuits over with a single neutral if it were three phase or two circuits if each of the hots where off different legs of the 220V. Did I get ripped off and should I have the bubba come back and run two more separate pieces of 12/3 romex?
    Guy Cox

    Life isn\'t like a box of chocolates...it\'s more like a jar of jalapenos.
    What you do today, might burn your butt tomorrow.
  • JR
    The Full Monte
    • Feb 2004
    • 5633
    • Eugene, OR
    • BT3000

    #2
    Sounds like one circuit to me. How does one connect a single piece of romex to three circuit breakers?

    JR
    JR

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    • LCHIEN
      Internet Fact Checker
      • Dec 2002
      • 21031
      • Katy, TX, USA.
      • BT3000 vintage 1999

      #3
      whoa, just a minute, sounds like confusion over terms.

      dO YOU HAVE ONE NEW CIRCUIT BREAKER, with one piece of 12/2 Romex (12/2 has a white wire, a black wire and a bare ground wire - really three wires but they don't count the ground) leaving the breaker box, running to three duplex (that's one over-under pair of receptacles) outlets? THis would be quite normal. It would be one circuit. Do you think because it has three duplex outlets that it's three circuits?

      Three circuits would be three breakers, each connected to one piece of Romex (three total), each Romex going to one or more outlets.
      Last edited by LCHIEN; 04-12-2012, 08:39 PM.
      Loring in Katy, TX USA
      If your only tool is a hammer, you tend to treat all problems as if they were nails.
      BT3 FAQ - https://www.sawdustzone.org/forum/di...sked-questions

      Comment

      • BigguyZ
        Veteran Member
        • Jul 2006
        • 1818
        • Minneapolis, MN
        • Craftsman, older type w/ cast iron top

        #4
        If you're running 12/3, you can have two circuits (two separate breakers: Red wire is one circuit, Black wire is another circuit, White is shared neutral, and bare copper is shared ground). But you can't have 3 circuits. If you have 3 new breakers, I'm wondering if he ran red, black, and the white as the hot for them, and then used the bare copper as a shared ground. Then that would leave all 3 circuits as ungrounded, which is a safety hazzard.

        I'm not a fan of having shared anything on circuits. The only time I run 12/3 or 14/3 would be for 220V or when doing 3 or 4-way stiches for lighting.

        Comment

        • mineengineer
          Established Member
          • Feb 2005
          • 113
          • Pittsburgh, PA, USA.
          • BT3000 and BT3100 Frankensaw

          #5
          Exactly what did he do?

          How many breakers were installed? What kind of wire did he use hopefully romex NMB? What shape (flat or round) and or color(white, yellow, orange, gray) is it ? Can you read/see if it says 12/2 wg(which has two insulated and one bare ground wire)or 12/3 wg(which has three insulated and one bare ground) or 12/4 wg (has 4 insulated and a bare ground). What brand of breaker box did he install the breakers in and are they adjacent or beside each other in the box(depending on where they are at makes them on the same or different legs and determines whether the neutral is carrying the difference in amperages or the total of amps running through each hot)
          Link

          Comment

          • chopnhack
            Veteran Member
            • Oct 2006
            • 3779
            • Florida
            • Ryobi BT3100

            #6
            Wow.... can't wait to hear back from Guy on this one!
            I think in straight lines, but dream in curves

            Comment

            • jseklund
              Established Member
              • Aug 2006
              • 428

              #7
              I have never seen 12/4, but if it exist then I guess you could run 3 circuits on it. As stated before, he could have run a 12/3 wire and used the ground as the neutral, which I actually saw a licensed electrition do recently in the 1880 remodel I'm doing. He ran 12/2 for a dryer, and was going to use the ground for the neutral. Luckily I caught it and I ran my own wire. 12/3 would be the same setup - but with an additional circuit. Not safe.

              Another way that this could be done - did he run a sub-panel? He could have run 10/3 or 12/3 out to a sub-panel, and then installed 3 breakers on that sub-panel (or 4, or 5, or whatever).

              It sounds fishy...
              F#$@ no good piece of S#$% piece of #$@#% #@$#% #$@#$ wood! Dang. - Me woodworking

              Comment

              • Tom Slick
                Veteran Member
                • May 2005
                • 2913
                • Paso Robles, Calif, USA.
                • sears BT3 clone

                #8
                Originally posted by jseklund
                I have never seen 12/4, but if it exist then I guess you could run 3 circuits on it. As stated before, he could have run a 12/3 wire and used the ground as the neutral, which I actually saw a licensed electrition do recently in the 1880 remodel I'm doing. He ran 12/2 for a dryer, and was going to use the ground for the neutral. Luckily I caught it and I ran my own wire. 12/3 would be the same setup - but with an additional circuit. Not safe.

                Another way that this could be done - did he run a sub-panel? He could have run 10/3 or 12/3 out to a sub-panel, and then installed 3 breakers on that sub-panel (or 4, or 5, or whatever).

                It sounds fishy...
                12/4 would function but not be code compliant circuit like a shared neutral 12/3 is.

                Until recently, 12/2 was the standard way to wire a 220v drier or range circuit because there is no neutral in a 220v single phase circuit. The code changed to add a neutral so appliances could operate on both 220v and 120v concurrently.
                Last edited by Tom Slick; 04-17-2012, 07:29 PM.
                Opportunity is missed by most people because it is dressed in overalls and looks like work. - Thomas Edison

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