Conduit For Infloor Heating (from Floor / Plate Up To T-stat Box) - Electrical - DIY Chatroom Home Improvement Forum
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Old 12-01-2010, 11:03 AM   #1
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conduit for infloor heating (from floor / plate up to t-stat box)


Hi all - I have a small installation (bathroom) in-floor heating using a product from Thermosoft - the 120v option and also purchased programmable thermostat with built in GFCI. I have a dedicated circuit wired for this. Total wattage listed by the manufacture is @270 watts (less than 16 sq ft heating a small area).

The manufacturer recommends at least 3" of the lead wire (at the splice) be embedded - I buried about 12" (still have lots left to get to the box). The cable / mesh is embedded in SLC and I drilled the bottom plate to run the leads (heating wire and sensor) thru the bottom plate. All flooring work done with the help of others on these forums

The lead wire from the splice back to the box has a braided jacket and seems pretty durable. You can sort of see a couple pics of the splice for this product in their install page:
http://www.thermosoft.com/radiant-fl...nt-floor-heat/

The instructions mention using a conduit for the lead wire up to the box as optional - i.e. if required by code. I'm not sure if this is a code requirement in Canada / Ontario. if so, is this intended to protect the cable, or also the building materials (does the lead wire get too "warm"?). I'm wondering if I can tack on a few insulated staples to run the lead wire up the wall stud to the box, and maybe a plastic gasket / clamp at the box knockout to protect the wire there. Is this an option?

If conduit is required, can I use the flexible non-metallic (PVC) style conduit like the ones sold at the box stores (e.g. the blue stuff @ Home Depot)? That would make my job a bit easier.

Thanks in advance...
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Old 12-06-2010, 04:22 AM   #2
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Okay here is what I did. I drilled 2 1" holes on the bottom plate of the wall and then drilled about 1/2" holes through the side of the treated 2x4 basically where the floor trim attaches to. I then pushed 1" pvc conduit down into the hole and ran the thermostat lead and the line coming from the heated mat up to the actual thermostat. I wanted them in two separate pvc tubes so they would not interfere with each other. I did this and it has worked flawlessly.
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Old 12-06-2010, 11:20 AM   #3
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Quote:
Originally Posted by ryan5068 View Post
Okay here is what I did. I drilled 2 1" holes on the bottom plate of the wall and then drilled about 1/2" holes through the side of the treated 2x4 basically where the floor trim attaches to. I then pushed 1" pvc conduit down into the hole and ran the thermostat lead and the line coming from the heated mat up to the actual thermostat. I wanted them in two separate pvc tubes so they would not interfere with each other. I did this and it has worked flawlessly.
thanks Ryan - do the 2 sections of conduit run right into the thermostat box or does the PVC terminate somewhere short of the box with the leads then continuing into the box?
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Old 12-08-2010, 06:35 AM   #4
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Well I made my fit nice and tight right under the hole openings in the bottom of the box. I used the blue new construction box with 2 holes on the bottom and two on the top I ran all my electrical from the top and the bottom holes I dedicated to the power supply lead and the thermostat line. If you want make the fit pretty snug them use some hot glue or something to keep it from moving on you. That is what I did. I am sure you can do it anyway you want but I just liked the idea of them being seperate and it just looks clean which I am all for. Thanks and good luck!
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Old 12-08-2010, 07:53 AM   #5
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I used the non-rigid blue stuff from H.D. to do mine. Drilled holes in the top and side of the bottom-plate. It's funny that the low- and line-voltage wires both connect to the back of the thermostat, seems like they should be isolated in the box as well as on the way down to the floor, but the one I used (SunTouch) did not have a separator in the j-box. But, it's working fine.

Word of advice...run two temp sensors. Connect one to the thermostat, leave the other dangling in the j-box. The temp sensors can break, and you're pretty screwed once the tile is down. This way, you have a backup. For my installation, the backup temp sensor only costed $14.
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Old 12-08-2010, 12:00 PM   #6
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thanks guys - yes I do have a spare sensor in the floor (the vendor recommended it - figured it was a good idea - the add'l cost was somewhere @ $16). You're right it's a small price to pay in the big picture to get some peace of mind.

it sounds like the only difference in my install is that I notched the bottom plate (it's a 2x6 wall) in about 2" as opposed to drilling side and top (the manufacturer instructions said just cut a notch). I can easily fit the end of the blue flex stuff in the top of the notch. I got a chunk of the conduit from HD now - also grabbed a couple of the snap in blue box clamps to connect the conduit right to the box. But if I have to wrestle with it at all I might just attach the end of the conduit to the stud right under the box and run the last couple inches of wire out the end of the conduit in the air and then up into the box.
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Old 12-08-2010, 12:34 PM   #7
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I'd snap the blue conduit right to the box. The knockouts on a metal box can be sharp, you don't want to damage the insulation. The snap-in connectors work fine. You can get a snap-on male threaded end and a (metal) locknut to screw the conduit into the box.
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Old 12-08-2010, 12:56 PM   #8
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will try that - thanks all for the advice and feedback
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Old 12-09-2010, 12:25 AM   #9
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Great idea on running two sensors. I didn't even think of that. Hopefully mine does not fail or I have a large project on my hands that is for sure. I will know for next time that is for sure.
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