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hewaschuk · Feb 14, 2008, 07:48 AM

I want to put in under-the-tile floor heating in my bathroom, which is being renovated. The instructions that come with the heating cable say that the circuit for the heating wire must be separate. This is impossible to do!
The heating wire that would go in is rated at only 300 watts. Is there really a danger in hooking this up to my bathroom/bedroom circuit. Or does the impedance of a 300 watt resistive heating circuit have some effect on the circuit breaker operating properly on overload?

KISS · Feb 14, 2008, 09:34 AM

If it's IMPOSSIBLE because of spaces in the breaker box, then use a breaker that takes up one slot, but has two poles where the poles aren't connected mechanically. My brain can't think right now for the name of the breaker.

You might be better off using tubing that's heated with water (radiant heating), because electric elements can burn out and you'll have to rip out the floor to replace it.

hewaschuk · Feb 14, 2008, 09:59 AM

The problem is not the service panel, it is getting a cable from the second story bathroom to the panel in the basement. All walls and ceilings are finished, so it would be a huge job.
Hot water doesn't sound like a solution to me since I have hot air heating in the house, not hot water. Also, it seems to me that the chance of getting a water leak is about the same as the electrical heating cable burning out.

KISS · Feb 14, 2008, 10:31 AM

I'd say 300 W should not be a problem, but I would not put it on any critical circuit like a fridge and I would protect it with a combo AFCI/GFCI breaker. AFCI's are required for bedrooms.

steven62 · Jun 17, 2008, 02:18 PM

If you share a circuit with an electric floor heating system, follow these rules:
NO GFI's allowed on the same circuit.
Make sure the breaker is 25% greater capacity than the maximum draw.
Maximum 20 amp non GFI breaker
Then you should be O.K.
The reason for this is that the controls that come with these have GFI's (Actually Arc fault detectors) built in, and they will "trip" over any other GFIs' on the circuit.

hewaschuk · Jun 17, 2008, 02:37 PM

Originally Posted by steven62

If you share a circuit with an electric floor heating system, follow these rules:
NO GFI's allowed on the same circuit.
Make sure the breaker is 25% greater capacity than the maximum draw.
Maximum 20 amp non GFI breaker
Then you should be O.K.
The reason for this is that the controls that come with these have GFI's (Actually Arc fault detectors) built in, and they will "trip" over any other GFIs' on the circuit.

Thanks, seems like good advice. Could a GFCI be used in parallel, i.e. I will also be feeding an outlet close to the sink in the bathroom from this circuit, and would like to provide GFCI protection there.

steven62 · Jun 17, 2008, 03:59 PM

Just so you know where I am coming from, I am tech support for Watts Radiant Suntouch, so my advise is general for all systems, particular for Suntouch!
You can sometimes get away with a GFI outlet, if it is "downstream" of the thermostat (drawing power after) This is "iffy" but usually works as long as they are not too close together. I really don't understand why, maybe an electrician can chime in here?

robomaniac · Jun 19, 2008, 04:32 AM

Originally Posted by KeepItSimpleStupid

If it's IMPOSSIBLE because of spaces in the breaker box, then use a breaker that takes up one slot, but has two poles where the poles aren't connected mechanically. My brain can't think right now for the name of the breaker.

Square D make those twin breaker. There are few compagnie that makes them.

You need a Square D breaker box to install them!

hewaschuk · Jun 19, 2008, 08:11 AM

The problem is not the service panel, it is getting a cable from the second story bathroom to the panel in the basement. All walls and ceilings are finished, so it would be a huge job.