Amps needed for electric radiant heat

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  #1  
Old 08-03-07, 08:23 PM
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Amps needed for electric radiant heat

I'm in the process of finishing my basement and I'm installing a small bathroom where I will install in-floor electric radiant heat. The square footage to be covered will be 15 square feet.

The manufacturer recommends 0.1 A/square foot, so that means I only need 1.5 amps.

Prior to deciding to tackle this myself, I had an electrician give me a quote. He quoted the job using a 20 amp circuit. I know I need to run a dedicated circuit, but is there any reason to go with a 20A (I'm know he was going use different materials than me)? Seems like overkill to me, but I want to make sure I'm not missing something since I'm not a pro.

Thanks in advance.
 
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Old 08-03-07, 08:34 PM
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Wink

Id say he knows what he is doing and he is a pro.
 
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Old 08-03-07, 10:00 PM
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The only options are 15A or 20A circuit, and the price difference is very small. The labor is the same and all of the parts are the same (15A breaker is the same price as 20A). The only difference is #12 cable instead of #14 cable, which is a very small increase in cost. The 20A circuit would allow you the flexibility of installing a larger system someday when the bathroom is re-remodeled.
 
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Old 08-03-07, 10:45 PM
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Any kind of equipment fastened in place (with the exception of the vanity light fixture) located in bathrooms by code are to be on a 20 amp circuit regardless of amperage. You can tie into your Heat/Vent/light circuit if it is under 50% of the branch circuit ampere rating. 15 amp circuit would be a nec code violation and this is why the electrician quoted you for 20 amp circuit. In the same breath, the electrician also knows about what I mentioned above and may be trying to charge you for unnecessary work of installing a new circuit. I would get a few more estimates before choosing this guy.
 
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Old 08-04-07, 06:23 AM
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A 15 amp hardwired heater in a bathroom would NOT be a code violation. Code does not address hard wired equipment, code only addresses the receptacles.

That being said, put this heater on a 20 amp circuit.
 

Last edited by racraft; 08-04-07 at 12:37 PM.
  #6  
Old 08-04-07, 10:08 AM
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Originally Posted by jamead65 View Post
Any kind of equipment fastened in place (with the exception of the vanity light fixture) located in bathrooms by code are to be on a 20 amp circuit regardless of amperage.
Can you cite the code section that says this? As long as this circuit is not supplying the bathroom receptacles there is no code rule that would require the heat to be on a 20 amp circuit.
Don
 
  #7  
Old 08-05-07, 10:46 AM
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Thanks for all replies. The consensus is to use the 20 amp circuit, so that's what I'll do.
 
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Old 08-10-07, 03:52 PM
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As a follow-up to this post, I am wondering if I can run a multiwire circuit (12/3) to serve the radiant mat switch and also an outdoor receptacle that is about 9 linear feet away from the radiant switch? Can this be done and is it advisable. Or, should I just run 2 separate 12/2 wire, one for the mat and one for the outdoor receptacle?
 
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Old 08-10-07, 04:18 PM
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I am an advocate for multi-wire circuits, but I generally advocate against them in a residential setting unless absolutely necessary and unless people know what they are doing with them. My preference for them is to use a 240 volt breaker, even if not required by code, so as to avoid problems if the panel is reconfigured.

Yes, a multi-wire circuit could be used and it would work. I would run 12-3 to one location (probably the bathroom) and then run 12-2 to the second location (which would be the outside).
 
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Old 08-10-07, 05:22 PM
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Originally Posted by racraft View Post
My preference for them is to use a 240 volt breaker, even if not required by code, so as to avoid problems if the panel is reconfigured.
Thanks for the quick reply. Do you mean a single 240 volt breaker rather than two 120 volt breakers?
 
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Old 08-10-07, 07:00 PM
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Yes, I mean a double pole 240 volt breaker.
 
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