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So I'm planning on wiring in three 240v cove heaters in my master bedroom and bathroom (on two separate thermostats). I've read through the manufacturer installation instructions, as well as information regarding the NEC standards for installation, and I just want to make sure I have everything correct.

Here's my diagram of what I'm planning on doing. Diagram of Wiring

I had a couple questions in addition to this. I haven't found anything saying that 240v heater circuits need AFCI/GFCI breakers, is there a requirement for these in this circumstance? If not, would it be a good idea, or is it completely unnecessary?

Second, the cove heaters stick out about 1" from the wall, meaning the cable has an air gap to cross. I know there's a requirement to protect the cable from physical damage, but the manufacturer says not to use plastic conduit. Would this limit me to rigid/semi-rigid metallic conduit? Is there a way to clean this up to look a little nicer?

Thank you all for your assistance.

Edit1: More pictures Wiring Compartment

Picture of wall standoff

  • Many heaters have a self-contained junction box and can be fed with metallic clad cable. For accurate answers you should really give us the model number of the heaters you’ve chosen, so that we may google the installation manual. – Tyson Oct 28 '17 at 20:31
  • Sure thing, it's a radiantsystemsinc.com Comfort Cove C-9024 and C-6024. – tearman Oct 28 '17 at 20:35
  • Wow, they don’t have good online documentation or photos! If you already have the units, you might edit into your questions photo’s of the unit and any wiring compartment they may have. – Tyson Oct 28 '17 at 20:46
  • Yeah they don't, at least someone else agrees with me that's its a little unclear hahah. I edited some pics in. – tearman Oct 28 '17 at 20:50
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There is no need for arc fault on 240-volt circuits anywhere. The circuit that feeds the bath heater will have to be GFCI protected. I see no need for a junction box behind the heater. Just sleeve the wires with a short rigid nipple (my preference) or a nipple made of EMT. A rigid nipple entering the wall will need to be bushed to protect the wires entering. I would calk the hole entering the wall with latex calk and swipe it with a wet finger for a finished look.

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You bring your NM wall run into a junction box installed in the wall. Then either you continue the NM down the conduit into the heater proper (ugh, NM in conduit!) or you terminate the NM there and continue in THHN or a high-temp wire. Wire gage stays the same transitioning amongst NM, THHN, AC etc. I mean, you're always allowed to bigger than required.

I hope they provide a way to make that splice and button up the junction box without having to dangle the heater in the air while you do it.

They are recommending steel e.g. EMT conduit from there, I would certainly use EMT, or a nipple may suffice. Rigid is not worth fooling with, except in rare instances where the facts just work in its favor.

You could also put the junction box past the end of the heater, come out of it with an LB elbow and into the heater, or surface mount the junction box past the end of the heater and have a short bit of conduit or nipple coming over.

This thing has to touch the wall somewhere, part of that physical mounting may include a raceway for electrical power.

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  • Thanks for the info. I guess I should've drawn that on there, but I was indeed planning on putting junction boxes and faceplates on the egress point of the wall. With THHN, do I go like-for-like with cable gauge (i.e. use 12 gauge)? Or is there a conversion? Also dumb question, I have 600v armored cable, could I use it in this instance if it were 12-gauge as well? I double checked and the mounting bracket is literally just stamped sheet-metal with no conduit. Only other thing in the kit is a couple end-plates. – tearman Oct 28 '17 at 19:12

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