In floor heat is roughed in. What do I need now?

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Posted by: from Calgary
1/29/2014 at 12:27:35 PM

In floor electric heat is roughed in for the main and master bathrooms. There are just blank plates on the wall where the controllers would be.

Do I need anything specific to get this operating or can I just purchase and wire up timer/controllers for these?


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Robert from Electrilight Ltd. in Oakville
Date/Time1/29/2014 at 4:59:41 PM

Did you do a resistance test on the floor heating and test for grounds or shorts PRIOR to laying the floor?

Very common mistake that can make you break it all up again..

The T-stat needs to be compatible with the floor heating, some are 120, 240 line voltage only, some are low voltage and they all must be GFCI protected and if each mat is more than 300 watts, should be wired newly to a new circuit breaker.

Ontario regulates electrical contractors to ensure all work is to code, and home owners can get permits so the work is checked and known to be safe from fire or shock hazard.

If you can get an inspector in or have an electrical contractor come by, best to get the advise they offer for $100 or so, since you already saved by doing some of the work yourself, this small amount is well spent on hooking it up.

Good luck!

Kind regards,

Robert McKinnon (Master Electrician/Owner)

Electrilight Ltd.

Professional Electrical Services, contracting and inspections. ESA member

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Darrel in Calgary
Date/Time1/29/2014 at 6:57:47 PM

Thanks for the responses.

I have not done any tests yet. This is an infill house that was built in 2009. The rough in was done by the building contractor. I have a reasonably good multi-meter. What resistance should I be looking for?

Thanks again.

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Robert from Electrilight Ltd. in Oakville
Date/Time1/29/2014 at 7:42:23 PM

You need to find out the mat details from online or the retailer for that info. All mats are a bit different, so make, model and length are crucial.

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Darrel in Calgary
Date/Time1/30/2014 at 8:19:06 AM

Thanks again Robert.

The builder is no longer in business so it will indeed be tricky to find out what mat is installed.

Wish me luck.

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Robert from Electrilight Ltd. in Oakville
Date/Time1/30/2014 at 1:52:41 PM

Biggest issue is whether it is 120 volt or 240v.

You can apply 120 volt to the leads and leave it for 2-3 hours and see if the floor heats. Just make sure you wear rubber sole shoes while testing it. If it does not heat it may be a 240 volt mat.

If it has 2 sets of wires, a smaller thinner set and a larger solid copper set, the larger pair will be the power lines and the thinner may be the thermistor (thermocouple) to tell the T-stat what temp the floor is and adjust as needed. If there are the smaller wires, DO NOT apply voltage to them or you will burn the thermistor out.

Attach a photo or 2 here maybe and we'll try and figure it out.

Any labels on the wires???

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Darrel in Calgary
Date/Time1/31/2014 at 8:12:58 AM

Hi Robert.

I will pull the plate off the wall again and see if there are any labels or markings on the wires. There are also two breakers labelled for the two bathrooms. Pretty sure they were 15 or 20 amp. 110V but I'll have another look when I get home tonight.

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