1. Junior Member
Join Date
May 2018
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United States
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1

## 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. gar
Senior Member
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Apr 2008
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Ann Arbor, Michigan
Posts
6,981
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. Senior Member
Join Date
Sep 2011
Location
woodbridge, ct. USA
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1,117
Originally Posted by gar
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. 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. Senior Member
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Jun 2003
Location
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.

6. Originally Posted by Tony Ledford
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.

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