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Thread: Help with a 120V circuit

  1. #1
    Join Date
    Nov 2007
    Posts
    591

    Help with a 120V circuit

    I got a call late in the day to a residence that lost power to several receptacles and lighting. I checked a recep in ??? and found 120V from hot to ground, 120V from neutral to ground, and 0 V from hot to neutral.Could a broken neutral cause this scenario? Owner says that lights blinked several times before everything in that room went out. Breaker that supplies power to this room is part of a MWBC, the other breaker is supplying power to another room adjacent to this one and all is working fine. I can't seem to find the box though where the MWBC splits. Any thoughts appreciated.

  2. #2
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    8,754
    Quote Originally Posted by nizak View Post
    I got a call late in the day to a residence that lost power to several receptacles and lighting. I checked a recep in ??? and found 120V from hot to ground, 120V from neutral to ground, and 0 V from hot to neutral.Could a broken neutral cause this scenario? Owner says that lights blinked several times before everything in that room went out. Breaker that supplies power to this room is part of a MWBC, the other breaker is supplying power to another room adjacent to this one and all is working fine. I can't seem to find the box though where the MWBC splits. Any thoughts appreciated.
    Sounds completely consistent with an open neutral and no loads on that stretch of neutral from the other side of the MWBC. If you find where they split, that is the most likely place for the bad connection. Try a live circuit wire tracer on the neutral from an outlet in the room back toward the panel or open the breakers on both sides of the MWBC and use a dead-circuit tracer.

  3. #3
    Join Date
    Sep 2006
    Location
    Memphis, TN
    Posts
    1,217
    Quote Originally Posted by nizak View Post
    I got a call late in the day to a residence that lost power to several receptacles and lighting.
    I checked a recep in ??? and found 120V from hot to ground, 120V from neutral to ground,
    and 0 V from hot to neutral.
    Could a broken neutral cause this scenario?
    Owner says that lights blinked several times before everything in that room went out.
    Breaker that supplies power to this room is part of a MWBC,
    the other breaker is supplying power to another room adjacent to this one and all is working fine.
    I can't seem to find the box though where the MWBC splits.
    Any thoughts appreciated.
    Dangerous !!!

    Think about what you are doing.

    Sounds like a dangerous MWBC in a Kitchen that I found.
    Had a call on one which had an Open Neutral return to a Electric Panel.

    The MWBC fed directly to the first Kitchen CounterTop Rec, with joints sending the phase A to the D/D.
    The phase A went to the Disposal/Dishwasher.
    The phase B went to the counter-top Rec.
    The Neutral feed from the Elc. Panel was broken at the first "Push-In" Rec on the Countertop.
    The Voltage reading at this First Rec was 120V hot to ground, 120V neutral to ground.
    The Voltage reading at this First Rec was 240V hot to neutral.

    The Mixer on the Kitchen CounterTop was throwing showers of sparks everytime it was plugged in.
    The Dishwasher had already stopped functioning.
    The Disposal Wall Switch was in the "ON" position.

    The phase A was feeding through the Disposal to the neutral, back to the CounterTop Rec.
    That is where phase A and phase B met each other, for the 240V reading.
    When the Feeder Neutral from the CounterTop Rec to the Electric Panel
    was connected properly to the CounterTop Rec,
    Then the 240V went away, down the neutral properly.

    Dangerous !!!

    Think about what you are doing.

    The fix was to replace the CounterTop Rec with a screw/clamp type.
    The rest of the house has the same problem, just not on MWBC.
    All the recepticals in the house require replacement with screw/clamp type devices.
    Glene77is, Memphis, TN. .....Electricity.is.Shocking.....·×º°”˜`” °º×_

  4. #4
    Join Date
    Jul 2013
    Location
    augusta,GA
    Posts
    1
    stabbed outlets

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