GFCI tripping of Warm Tile thermostat


Old 11-20-16, 06:17 PM
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GFCI tripping of Warm Tile thermostat

I have a 240V dedicated circuit installed in my bathroom for in-floor Warm Tile heating system in 2009 which ran perfectly until 2015 when the thermostat starting tripping about 30 minute when ever we turn on the unit.

The original thermostat was a GT-2. Electrician came to check it out and said that the wiring seem fine and then he reset the thermostat and it was fine. However, after he left about 30 mins, it would trip again. I can reset it but it would trip again. Electrician can back 2nd time and called the manufacturer who told him to do a reset by switching off the main circuit breaker for 30 mins. So he did that and then turn the unit on. Electrician then left and told me that it trips again, manufacturer recommends a new thermostat.

Given that I have already paid him about 2 visits of about 1 hr each for doing nothing to troubleshoot, I decided to order the new thermostat which is FGS 120/240V thermostat per the manufacturer. Instead of calling the electrician for the third time just to install the thermostat, I decided to install it myself.

I essentially moved the wires over to the new thermostat per instructions. Please see pictures attached. Now with the new thermostat, when I turned it on, the GFCI trips immediately and I cannot reset it. It would appear that the new thermostat might have done the job but guess not.

Any ideas would be much appreciated.
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Old 11-20-16, 09:06 PM
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Welcome to the forums.

I've been called in by several tiles guys as well as customers to troubleshoot their heated floors. To date... I've not had to change a defective control. The common problem was leakage thru the heating cable.

I use a very sensitive ohmmeter and I check from white to ground and black to ground on the heating cable with it disconnected from the control. Any continuity shown signifies a leaky (aka defective) heating cable.
Old 11-21-16, 06:20 AM
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I doubt it's the stat,just connect the line from the breaker to the line side of the stat,do not connect the heat wires to the stat, reset the breaker and see what happens,I would agree with Petes diagnosis.

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