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AC power circuit tracing

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    AC power circuit tracing

    I'm sure many people have had the problem of figuring out which circuit breaker supplies an outlet or light switch. When a home is new the breaker panel may be well labeled; after a few years that may no longer be true. After a few decades, it's almost certain not to be true.

    Of course, you can always turn off circuit breakers until the outlet / light in question goes dead. That usually results in resetting clocks, a lot of trips back and forth, etc. Necessity forced me to discover how to use a common piece of test equipment to make the process much easier.

    The long story is Sunday afternoon I was using a power saw in the garage when suddenly the light went out and the saw stopped. "Darn, I tripped the breaker" (or something more pungent) was my first thought. Go out to the breaker box, no circuit breaker has been tripped. Not good, definitely not good. A few years ago I upgraded the wiring in the garage, maybe one of those junctions is bad? Definitely not good, the junction point is up on the ceiling.

    On my way through the kitchen I discover the utility room, kitchen and dining room lights are not working either. OK, that moves the likely problem area back to the kitchen, which was remodeled nearly 8 years ago. As part of this remodel some wiring was torn out, and the kitchen lighting and outlets completely rewired. New circuits were run for the outlets, but the kitchen lights tapped into the old circuit. Clearly, the garage is on the same circuit. Now, where did I tie the new to the old??? After a quick phone call, I discover my son won't let me use his Tone 'n Probe. It looks like I'll have to do this the hard way.

    After removing half a dozen cover plates and outlets I locate the box that has both old and new wiring. And sure enough, one of the wires has escaped a wire nut. Removing the wire nut and gingerly trying to group the wires together isn't working. Eventually I get the dining room and kitchen lights working, but the wire to the garage won't cooperate.

    Well, now I can at least start flipping off breakers until the dining room lights go out. There are only about a dozen candidates (UGH!!!). Then inspiration strikes. I've got a clamp on ammeter. And if I pull the covers off the breaker box, I can reach the individual wires to each circuit breaker.

    So I induce my wire to sit at the light switch for the dining room, switching it on and off every two seconds while I check the current flow through each breaker. On the 8th try, I find one that the current changes by about 1 amps every two seconds. Eureka!!

    A few minutes later with the power off I can get all wires to cooperate, and once again everything is working. Well, until I put the outlet back into the box and one wire popped out again (sigh). Time to use a new wire nut.

    PlainBill
    For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

    Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

    #2
    Re: AC power circuit tracing

    I have the previous generation of the circuit tracer in the attachment. Works great on live circuits. Connect into circuit, scan breaker panel twice. Steady tone on circuit breaker to be turned off.

    It has two problems. First is you can't use the transmitter on circuits protected by arc fault breakers. The transmitter trips the arc fault, can be a good thing if you're trying to turn off that circuit. Second, all dimmers in the house must be turned completely off. They generate noise that is similar to the signal the transmitter generates.

    I've modded an extension cord so the transmitter can be connected to a light switch or tied into a junction box to trace circuits.

    Your local Lowe's and Home Depot have the Ideal 61-532 tracer for about $35USD.
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    Stupidity should be a crime, especially for drivers. I have NO patience for them.

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      #3
      Re: AC power circuit tracing

      Great idea using the clamp on ammeter!
      As for wires falling apart, ouch. I always twist the wires together solidly with pliers, so they stay together even before the wire nut goes on.
      36 Monitors, 3 TVs, 4 Laptops, 1 motherboard, 1 Printer, 1 iMac, 2 hard drive docks and one IP Phone repaired so far....

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        #4
        Re: AC power circuit tracing

        Originally posted by delaware74b View Post
        I have the previous generation of the circuit tracer in the attachment. Works great on live circuits. Connect into circuit, scan breaker panel twice. Steady tone on circuit breaker to be turned off.

        It has two problems. First is you can't use the transmitter on circuits protected by arc fault breakers. The transmitter trips the arc fault, can be a good thing if you're trying to turn off that circuit. Second, all dimmers in the house must be turned completely off. They generate noise that is similar to the signal the transmitter generates.

        I've modded an extension cord so the transmitter can be connected to a light switch or tied into a junction box to trace circuits.

        Your local Lowe's and Home Depot have the Ideal 61-532 tracer for about $35USD.
        Thanks for the information. That probably would have helped locate bot the bad junction and the breaker. The price is reasonable, too.

        PlainBill
        For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

        Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

        Comment

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