Is this safe????


Old 04-27-11, 08:33 AM
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Is this safe????

I want to connect an underfloor electric radiant floor heater mat under proposed new tile in small bathroom.
No open slots on 150wat panel for a new (dedicated) circuit. Don't want to upgrade panel/service just for small floor heater.
Can I tie into existing circuit (if not overloaded) with a pre-existing GFCI wall outlet?
I'm sure there may be something that I'm missing, but my logic says if there is a surge or overheat or overload, the GFCI protected outlet (upstream from heater mat) will trip and cut power to floor mat and/or may trip breaker in the panel.

Is this safe? Manufacturer says it should be dedicated circuit.

BTW it is a Laticrete 3'x5' floor warming mat 225 watts 120 volts
with digital thermostat 1500 watts 120 volts
Old 04-27-11, 09:55 AM
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What is the make and model of your electric panel? It may be possible to gain some extra spaces with tandem breakers. You can usually find this information from the label on the panel cover.

Is there space adjacent to the main panel to add a small subpanel?

The floor heating mat cannot share with the bathroom receptacle, but there are some other circuits it may be able to share with if the tandem breaker or subpanel options don't work out.
Old 04-27-11, 10:42 AM
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With 225 watts I'm sure you can find a lightly loaded circuit in your panel that you could tie the floor heat to. Worse case you could do a Ben suggested and install tandem breakers if your panel accepts them or just add a small sub panel for more circuits.

All electric in floor heat in bathrooms are required to be GFCI protected. However, the GFCI does not provide any surge, overheat or overload protection. It only protects you in case of a ground fault. Some electric floor thermostats provide GFCI protection but you need to make sure it is for personal protection (4-6mA) and not for equipment protection (30mA). If it is the latter you will have to add some other GFCI protection.

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