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Thread: GFCI nuisance tripping

  1. #1
    Join Date
    May 2018
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    GFCI nuisance tripping

    I have an electric floor warmingsystem. The thermostat has a 5mA GFCI and every other day the GFCI trips.
    I have run every test known to man; even a mA test and the readings are wellbelow the 5 mA. Does anyone have some words of wisdom that would help me lookat something I might have missed?


  2. #2
    Join Date
    Apr 2008
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    Ann Arbor, Michigan
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    18051035 EDT

    Tony Ledford:

    Get two identical models of brand new Leviton GFCIs. The only reason for Leviton is that in the past I have run some experiments on their units.

    Replace your present GFCI with one of these. The second GFCI is connected in parallel on the input side with the first. Possibly with leads as short as 1 ft. The second GFCI has no load. Then wait for one or both to trip.

    Assume just the first one trips, call it #1. Interchange the two GFCIs. Now #2 has the heater load.

    Wait for a trip again. If the tripping is still associated with the heater load, then the probability is high that the problem is from the heater load circuit.

    Is there some sort of inductive kick, or is there really an intermittent leakage path? To sort this out may be difficult.

    If you run this experiment, then tell us what happens.

    .

  3. #3
    Join Date
    Sep 2011
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    woodbridge, ct. USA
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    Quote Originally Posted by gar View Post
    18051035 EDT

    Tony Ledford:

    Get two identical models of brand new Leviton GFCIs. The only reason for Leviton is that in the past I have run some experiments on their units.

    Replace your present GFCI with one of these. The second GFCI is connected in parallel on the input side with the first. Possibly with leads as short as 1 ft. The second GFCI has no load. Then wait for one or both to trip.

    Assume just the first one trips, call it #1. Interchange the two GFCIs. Now #2 has the heater load.

    Wait for a trip again. If the tripping is still associated with the heater load, then the probability is high that the problem is from the heater load circuit.

    Is there some sort of inductive kick, or is there really an intermittent leakage path? To sort this out may be difficult.

    If you run this experiment, then tell us what happens.

    .
    Not really following you experiment here but isn't the OP talking about the t-stat itself that has it's own gfi protection?

  4. #4
    Join Date
    Feb 2007
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    USA
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    5,544
    I way to make sure no issue with wiring or the heat mat is to use a insulation test meter Megohmmeter or Megger. Set using the max test voltage recommended by the manufacture of the heat cable/mat usually 1k or 2.5k.


    If you install a lot of this you should have one. They can be pricey.

  5. #5
    Join Date
    Jun 2003
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    NE (9.1 miles @5.07 Degrees from Winged Horses)
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    I’ve had a different mfgs GFCI work where a Leviton would not. Not why, because IDK, it just did. I wouldn’t bet the farm on it working for you. Other than that, meg it.
    Tom
    TBLO

  6. #6
    Join Date
    Feb 2003
    Location
    Minnesota
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    6,772
    Quote Originally Posted by Tony Ledford View Post
    I have an electric floor warmingsystem. The thermostat has a 5mA GFCI and every other day the GFCI trips.
    Welcome to the Forum, Tony.

    This is an INTEGRAL GFCI in the thermostat. It's not a Leviton. Forget the Leviton.

    I agree that the resistance of the heating element needs to be tested according to the manufacturer's instructions. Google for the document.
    Another Al in Minnesota

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