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My Floor Heating System Keeps Tripping

Why the GFCI is Tripping

The GFCI in thermostats are Class A, which means below 5mA trip levels. As a result, UL requirements is a very sensitive this is a very sensitive trip level required by UL. Likewise, there are several instances that could cause “spurious tripping” or “nuisance tripping” due to electrical noise on the circuit.

Common instances include:

  1. GFCI on breaker and in thermostat: You should aim to only have one GFCI on the circuit.
  2. Dedicated Circuit: If the power supply is shared with other devices, and especially if these use a GFCI, the GFCI may trip due to issues on the line. In those instances, aim to isolate your floor heating system with a dedicated circuit breaker.
  3. 240V Nuisance Tripping: On 240V circuits, electrical panels have a single physical area where it is common for the breakers to be merged. In the case of GFCI breakers, all neutral wires connect together to the same neutral bus bar. To resolve nuisance tripping issue, you can relocate your 240V breaker on the panel in a more isolated location, or you can tie the neutral wire (for GFCI breakers) to the other neutral bus bar (alone).


Note: Outside of bathrooms, floor heating systems do not require GFCIs.


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