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  • Lost neutral leg

    Hi to all,
    Last night the power went out in one bedroom. A "recepticle tester" revealed that the neutral leg was missing. 125vac hot to ground, 90vac across legs and 25vac from neutral to ground. No recent work done and old work checks ok. Bedroom is out but the rest of the circuit is ok. Can't find any broken white wires and all the blacks are to brass. How do I trace out the neutral or find where it might be broken?? I don't have a reflectometer. (great for finding open splices on aircraft wiring). Any help would be greatly appreciated...Thanks...Tom..

  • #2
    Re: Lost neutral leg

    There are a couple of ways to attack this. I am assuming there is no power at all in the bedroom, no lights and no power to any of the receptacles. Shut the breaker off that controls power to that circuit. Pull all of the receptacles and switches out of their boxes leaving the wires attached. Make sure the wires or terminals are not contacting the boxes or ground wires. Turn the breaker that controls that circuit back on. If you have a wiggy or volt meter, go from hot to neutral with your tester and see if you have 120V at any of the receptacles. If that circuit terminates in that bedroom one of the receptacles will probably have only one cable coming into the wall box and that will be the end of the run. You want to find the beginning of the run to see if you have an operating neutral. Depending on how the house was wired, the circuit may start in a light switch box. You may find a couple of neutrals pig-tailed together with a wire nut there. With the power turned back off, pull on the neutral wires that are 'tailed together. If you find a loose one, retwist them back together with a pair of linesman's pliers and reinstall the wire nut. Turn the breaker back on and test your connections. If you are good to go, turn the power back off and reassemble everything. The other way, if you have a tone generator and are comfortable working inside a live load center (panel box), pull the breaker that controls the circuit you are working on, remove the hot wire from the breaker and isolate (remove) the neutral wire from the neutral buss bar. You're going to have to trace it back along the hot wire you removed from the breaker and see through which knockout the wire that feeds that circuit enters from. If the wire is good to the first device on that circuit you will have tone. Follow the tone to each device on that circuit until you lose the tone. The problem will be at the last device with tone or the wire between the last one with tone and the first device without it. Are the wires backstabbed into the devices (receptacles, switches)? If you lose tone at a device that is the first thing I would check. I never use the backstab orifice and always loop the wire around the side screw terminals. Hope that helps.
    Last edited by killavolt; 03-16-2009, 08:37 PM.

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    • #3
      Re: Lost neutral leg

      Thanks KILLAVOLT, the end of the line is in another bed room. That leaves 4 outlets and a switch. What I didn't like about the switch was it's wired with a white leg as the hot wire and black is the switch return. (I would have done the oposite and blackened the white with a magic marker.) Tonight I'am going away for a few days, will be back on the 26th. Hope one of the guys at the firehouse (volunteers) has a "tone Generator". You use it with the power off? (unenergized)??

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      • #4
        Re: Lost neutral leg

        Yes, the power must be off when you use a tone generator. By pulling the breaker and disconnecting the black wire that feeds the circuit in question you will have shut the power off to that circuit. What you have with the hot white wire is a switch leg, a pretty common way to control a light. The white wire should have been taped with black tape or black magic marker to identify it properly. From your description it sounds like that circuit is being fed from the ceiling box for the light. Pull the light and see if maybe you have a loose neutral like I described in my earlier post. Or you could start there with the tone generator.

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        • #5
          Re: Lost neutral leg

          The switch is fed from the box the recepticle is in and back again. The builders should permanently post a diagram of the house wiring before they cal sell it. You must know of many jack-*** shortcuts taken when orig builders did the work. Anyway, this morning I was putting the end recepticle back when I tryed it first with a tester and it was good. Checked the other room and everything was ok. Plugged a lamp into the circuit and out it went again. This is the recepticle with the switch and I think that the circuit starts there. Got to start packing or Bonnie will have a fit. I'll check back in a week unless I can get e-mail somewhere..Thanks again..Tom..

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          • #6
            Re: Lost neutral leg

            Before you go away be sure any suspect circuits are off and tape the breakers in the off position. Put a note on the door that no one is to turn them back on.

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            • #7
              Re: Lost neutral leg

              Check every device on that circuit. There is one loose connection that opens when a load is applied. If any of the devices are wired by means of push in connections that is the most suspect for a bad connection. Removed any pushed in wires and reconnect them with the switch screw terminals.
              info for all: http://www.hoistman.com http://www.freeyabb.com/phpbb/index....wwtoolinfoforu --- "I like long walks, especially when they are taken by people who annoy me."

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