I am trying to put a motion sensor switch in a surface mounted box as shown: front

However, the switch has a "plate" (where the "tabs" would be on a normal switch) that does not fit inside the faceplate as shown below: back


The only thing I can thing to do is cut that "plate" on the switch (with a hacksaw?)? It seems like even though I don't have to cut much, it'd be awwwfuly close to the hole where the nut is to hold the switch onto the faceplate (actually using a nut here seemed odd, but perhaps this is normal for these steel boxes?).

What am I supposed to do here?

------------- EDIT ------------ Here is how it turned out: With the mud ring, before the faceplate: enter image description here

Final result (using a nylon decora faceplate, because I haven't gotten a chance to go to a proper electrical supply house to get a metal faceplate: enter image description here

enter image description here

enter image description here

It does seem "less than fitting/flush", but it's better than it was!

  • have tried to reverse the faceplate? – jsotola Aug 3 at 1:37
  • what hapens if you mount the switch in front of the faceplate instad of behind? does the black part fit through that opening? – Jasen Aug 3 at 11:04
  • The switch does not fit through the decora opening (it didn’t even fit through the mud plate opening) – David Doria Aug 3 at 16:13

You can't use that kind of faceplate with that kind of device. (Unless you're willing to hacksaw off the wings, but that will mean it can only be used in this type of faceplate, and will never be mountable elsewhere because you will have destroyed the screw threads that mount the Decora faceplate).

You need this

enter image description here src

  • You install this cover ("mud ring").
  • Then, you install the Decora outlet (or any device) in the normal way. Those two nubs give you mounting holes in the normal location. Remember to remove the paper squares if you're grounding via the yoke.
  • Then install a common/normal (e.g. Decora) cover plate.
  • This works with anything that will bolt into a normal box. The only downside is the cover plate may overhang a bit, but a careful choice of cover plate will help that.

Technically these things are called "mud rings", because it's intended that you install the mud ring, then lay drywall over it. They are made in different depths for that purpose. They also make flat (0 depth) plates, do not use those because the Decora cover plate screws will bottom out if you do.

The large opening meets the requirement for accessibility without tools. Wires must stick out at least 3" beyond the surface.

What it's doing is emulating a common 1-gang "handy-box". Except with a many more cubic inches available to you. You need the cubes practically for bulky devices like these, and you need the cubes statutorially for box fill.

  • Do you need another faceplate on top of that? The opening seems too wide to fit the switch, no? – David Doria Aug 2 at 23:54
  • Yes, this works just like most other junction boxes. You install the cover. Then, you install the Decora outlet (or any device) in the normal way with the stock mounting screws. Remember to remove the paper squares if you're grounding via the yoke. Then finally you top it up with the normal cover plate appropriate for that device - Decora, switch, outlet, whatevs. – Harper - Reinstate Monica Aug 2 at 23:56
  • I was reading that it may not be a good idea to put a "normal" coverplate (like this homedepot.com/p/…-pipsem--NA--100356918--N) on a raised box like that because the corners aren't sitting flush with the surface (like they would be if there was drywall) so something (a broom handle, for instance) could get caught on them and break them. Seems like a nonsense concern to me, but since I'm new I'm just trying to learn the right way to do things! – David Doria Aug 3 at 0:21
  • @DavidDoria A competent electrical supply (meaning not you-know-who) will stock narrow/small metal face plates that are pretty good for this, with very little overhang. Since you work in EMT, you should buy from real electrical supply, because they have all this weird stuff, and also they are significantly cheaper on anything not a massive commodity. For instance 4-11/16" boxes for $3 instead of $6. – Harper - Reinstate Monica Aug 3 at 0:30

You could try cutting the top and bottom switch plate but there's a good chance you'll damage the motion sensor in the process. If I were you, I'd go to an electric supply store and get the proper switch cover and face plate.

  • 1
    That's a 4x4x2.125 steel box. It's difficult to find a switch box that's more proper than that one, given that he's using the EMT wiring method. I suppose he could switch to a 1-gang handy-box, which would mount more logically, but he probably won't have the practical cubic inches. – Harper - Reinstate Monica Aug 3 at 0:02
  • I didn't realize the box was so deep. Thanks. – JACK Aug 3 at 0:10

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