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I am installing one of these infrared heating panels hardwired on my ceiling.

My plan is to put a junction box into the ceiling (same size as a ceiling light), located underneath the panel. The wire to the panel will need to exit from the box somehow.

Can this box be left open behind the panel? In contrast to a light fixture, the panel is not fixed to then junction box but attached with separate screws.

If it should be closed, how?

Here is how this would look from the side:

enter image description here

Note that the (metal) junction box will not be flush with the ceiling because I need to fix it to the beam (there will be 1-2 drywell thickness in between). Also the cable that connects to the heating panel is not Romex. It will be a flexible cable, similar as the ones for lighting fixutures.

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2 Answers 2

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You've got two options:

Cord/plug

I don't recommend this. But the linked unit comes with a cord/plug. You can install a junction box flush to the ceiling and put a standard receptacle in it. The receptacle and matching faceplate form a cover for the box. I did not originally recommend this method, but now that I know the hardwiring method is not by replacing the cord/plug with appropriate cable (NM cable or a wire whip) but rather by chopping the plug off and wiring the end of the cord into a box, I would recommend cord/plug installation.

Plug in the heater and attach it to the ceiling. as long as the cord is not pinched, looped (too many loops will cause heating in the cord) or otherwise messed up you should be fine.

Hardwired

The factory installed cord connects to some sort of junction box on the back on the unit. I suspect (but couldn't easily find instructions) that hardwiring is done by:

  • Open the integral junction box
  • Disconnect the cord
  • Connect a piece of NM cable (could be wire nuts or screw connections)
  • Close the junction box
  • Install a junction box on the ceiling
  • Connect this NM cable to the wires in the junction box using standard methods
  • The NM cable should be installed through an appropriate clamp in each junction box
  • Install a blank cover on the ceiling box
  • Install the device on the ceiling
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  • Yes, I want to hardwire it and it is officially supported. I could not yet find a way to open then integrated junction box so I think I may need to cut the cord but I asked. Regardless, my question is about the OTHER junction box. If this box is in the ceiling, how would I attach a clamp? How would I route the wire out if there is a cover on it? Note, the jbox would look same as for a ceiling light. I hope my question is clear
    – divB
    Commented Dec 10, 2023 at 17:16
  • It depends on the type of box. For example, with a metal box you can use one of these covers which has a 1/2" knockout and you put a clamp in the knockout. You are not allowed to cut the cord for a permanent installation because cords can't be used where NM is supposed to be used, and vice versa. You need to get instructions from the manufacturer about how to properly hardwire.
    – manassehkatz-Moving 2 Codidact
    Commented Dec 10, 2023 at 17:20
  • Oh I see. Ok I’ll get a metal box and this cover then. Good to know. But why not? I thought, the proper way is to cut the cord, strip it (=use as a pigtail) and then use wire nuts in the external junction box.
    – divB
    Commented Dec 10, 2023 at 18:09
  • Is there likely to be a problem by cutting the cord and stripping it, etc.? No. But it is not to code. Code recognizes different types of cables for different situations. Cordage is designed to be flexible and also to be used in open air (which dissipates heat). Non-metallic cable (a.k.a., Romex) is not designed to be very flexible (bend it and it keeps its shape) but is designed to be run inside walls. One critical example is that cordage can, depending on the product, use thinner wire than standard for cables run inside walls. For a temporary fix cut cord/etc. would be fine. Not permanent.
    – manassehkatz-Moving 2 Codidact
    Commented Dec 10, 2023 at 18:14
  • 1
    Yes, a switched receptacle is perfectly fine. The usual concern is that the receptacle might get used for other things that shouldn't be switched, but not an issue at all with a ceiling receptacle.
    – manassehkatz-Moving 2 Codidact
    Commented Dec 12, 2023 at 0:37
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It looks from your diagram that the panel will be spaced away from the ceiling surface. There's no reason in the world to attach the junction box to the joists, or to have it buried inside the ceiling cavity. The only reason you need a junction box is to provide protection for the wire connections, which can be done with a surface-mounted metal pancake box, 1/2" or so deep. It can be mounted by using screw anchors in the ceiling drywall. The feed cable can emerge from a small hole in the ceiling and connect to the knockout hole which the pancake box will have in its back. It does not need a cover if the panel surface under it is non-combustible, which would astonish me if it was not. Light fixtures are installed all the time with no covers (other than the fixture itself) over the box.

FYI, it is not code-compliant to cut the plug off a flexible cord and use it to hard-wire a device.

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  • Ok, I can use a surface mounted pancake box. However, I was thinking a larger and more rigid metal box gives me more flexibility and it makes me feel better if it's solidly attached to the beam rather than drywall. Further: There will actually be multiple of these heating panels and a larger and robust metal box would give me the option to splice them flexibly at multiple locations or install a relay for remote control. Is there a big reason not to "bury" the box (and attach to beam)? "Ceiling" on the picture is just normal drywall thickness.
    – divB
    Commented Dec 11, 2023 at 7:58
  • "The feed cable can emerge from a small hole in the ceiling". Do I understand correctly that you'd drill a hole next to the junction box to feed the cable to the panel out?
    – divB
    Commented Dec 11, 2023 at 8:00
  • I got the following answer from vendor: “ To hardwire the units your electrician will cut the plug and will hardwire the heater by using the cable, but not the connection box. The connection box is not to be opened. Please note the hardwiring must be done by a certified electrician.”. As I expected they want to cut the cord. Do you have a reference why cutting the cord would not be code compliant?
    – divB
    Commented Dec 11, 2023 at 20:48

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