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    donf's Avatar
    donf Posts: 5,679, Reputation: 582
    Printers & Electronics Expert
     
    #1

    Nov 8, 2011, 11:12 AM
    Problem Branch Circuit
    Greetings,

    My Niece has a problem with a branch circuit that is intermittently cutting out and dropping circuits in two bedrooms.

    The branch circuit, originates at position 14 on the panel. It is a 20 amp circuit.

    I tested the output of the breaker at the panelboard and it was reading 120 VAC.

    The home run goes from the panelboard to the first of two lights in the upstairs hallway. At the second light, the circuit splits and feeds several circuits in the master bedroom and all of the circuits in the 2nd. Bedroom.

    Both lights in the hallway are on. Apparently they wired from the first light to the second light using 12/3. At the second light, the red conductor feed the bulb on the second light.

    The black conductor then connects to a bundle of blacks, which at this point I am guessing is the junction for the other two bedrooms.

    There is 120 VAC between the neutral at the second light and the bundle of black conductors.

    Neither of the bedrooms show any voltage. The first device in the circuit in the second bedroom is a fan/light. The switch loop to and from the light circuit has been verified using an Ohm meter.

    There is no voltage present in any of the rooms outlets.

    The original failure was that at intermittent times, the circuit would just drop dead and both bedrooms would lose power for several hours and then the circuit would just reactivate.

    I checked the entire circuit for loose Neutrals, but I did not find any.

    I'm open for more suggestions, please.
    smoothy's Avatar
    smoothy Posts: 25,492, Reputation: 2853
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    #2

    Nov 8, 2011, 11:19 AM
    Is there any possibility there is a junction point that you missed, possibly because someone illegally covered it up with a Sheetrock repair in the past, or that it hits a junction box in the attic?
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #3

    Nov 8, 2011, 04:43 PM
    Smoothy,

    The answer is a rousing, "Could be". I have lung problems that prevent me for clambering around in blown insulation, so I am prohibited for going up to the attic.

    I suppose I could take a length of Cat 5 cable and wring out the wiring to make sure there is continuity on each cable, but I hoped to avoid that.

    Initially, I thought is was a heat related problem causing the conductors to separate until they cooled off. Almost like a defective meter base. But I saw no heat marks on the meter base pins, nor is it an entire phase bar that is out. It's just this one circuit.

    There were no repairs done to this home. Also, the problems seemed to have started after the 2nd. Bedroom fan/light was replaced.
    smoothy's Avatar
    smoothy Posts: 25,492, Reputation: 2853
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    #4

    Nov 8, 2011, 08:27 PM
    Do you have a fox and Hound tester like used on phone circuits. Isolate that branch at the breaker... and have a helper see if they can track it down in the attic for you... Set it for a warble tone and you just have to get near the line to identify it... through a wall is likely too much distance. Just tossing out an idea there how one MIGHT find it. Without a guess factor. I have some others but the likelihood you would have access to some of the equipment would be very remote... because you would use it to create a very low power transmitter using that line as an antenna and that would let you track it through Sheetrock.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #5

    Nov 9, 2011, 07:32 AM
    Update:

    This morning at 2:00 AM, the lights and receptacles became energized again.

    What this means to me is that the wiring is contiguous and operational to the entire circuit.

    Why does this look like a heat problem or an open neutral and why is the failure so intermittent and solid a failure at the end of the circuit?
    smoothy's Avatar
    smoothy Posts: 25,492, Reputation: 2853
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    #6

    Nov 9, 2011, 08:20 AM
    I'm thinking attic connection, the one you don't know about... that area of the house has big temprature swings over the course of a day... framing shifts ever so slightly, and wiring will expand and contract ever so slightly... if there is a loose connection or say a wire nut that wasn't properly installed, you have an opening for that sort of thing to happen. It may take a long time to manifest itself... and will get worse over time.

    Exterior walls will be effected as well to a lesser degree.
    tkrussell's Avatar
    tkrussell Posts: 9,659, Reputation: 725
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    #7

    Nov 9, 2011, 12:08 PM
    Load on the circuit also heats up poor connections, causing the connection to open until it cools off.
    donf's Avatar
    donf Posts: 5,679, Reputation: 582
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    #8

    Nov 9, 2011, 03:28 PM
    But would heat generated by the load knock out the two bedrooms and stay hot for more than 24 hours?

    Usually, the problem will happen at odd times. The receptacle in one bedroom only supplies an alarm clock, the same run feed a fan/light combo. The failure shows up when the clock goes out.

    The other bedroom has a light and a receptacle in the bathroom. Neither have to be on when the circuit dies.
    smoothy's Avatar
    smoothy Posts: 25,492, Reputation: 2853
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    #9

    Nov 9, 2011, 07:16 PM
    Not necessarily... but it needs any combination out of balance to break... but also for them to reconnect suitable conditions need to return... and its likely explained by more than one variable at play in this case.

    Basically beyond the fact its happening... and the fact it could become a fire hazard... no need to over analyze it beyond the fact you know it's there someplace.

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