I am replacing a dimmer with an LED compatible dimmer. I have two problems.

1) I can't find an LED dimmer narrow enough. The Lutron dimmer that I bought is 1 3/4" wide. The box is a little less than 2 inches wide and the box tabs are very close to the screws on the dimmer.

2) Whoever installed this old work box didn't secure the romex.

I see two possible solutions:

1) Find a narrower dimmer. Use a press-on plastic clamp to secure the romex.

2) Replace the box with a slightly wider non-conductive box with a built-in clamp.

My primary question: how difficult is it to remove this box? I think that it is held in by the tabs, so if I bend them out the box should come out. What about the tabs, will they come out easily? I don't want this simple project to spiral out of control.

Any other suggestions?

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This is the box I am considering:

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Edit: Resolution: Reused the metal box. Used a dimmer with wires instead of screws. Still a tight fit. Added a clamp to secure the romex (had to take the box out to add the clamp, thx to Jack for the tips). Labeled the wires (white was line, black was load/lamp :( ). Used a clip to ground the box (wasn't grounded before).

  • 2
    Find a narrower dimmer. One that doesn't require a neutral, because I'd assume that white wire isn't one, and should also be re identified as not being one, with black electrical tape along its entire length.
    – Mazura
    Commented May 31, 2020 at 0:20
  • LED dimmers are significantly larger. I ran into the some problem with old steel boxes. I had to open up the wall a little and put in a larger box.
    – mreff555
    Commented May 31, 2020 at 0:29
  • 2
    To elaborate, the black and white wires in this cable are being used as a "switch loop". One of the wires is an always hot and the other is a switched hot to take power to the hot side of the light fixture. The required neutral for the fixture is in the box holding the fixture. This was perfectly acceptable wiring decades ago, but modern wiring practice is to have a neutral in the switch box. You must use a dimmer that does not require a neutral. Commented May 31, 2020 at 19:05

2 Answers 2


The box is very easy to remove. Just straighten the four tabs and the box will come out, the taps will fall to the floor behind the drywall unless you hold on to them and slide them out from behind the wall in the event you want to reuse the box.

You could use the existing box once you attach the NM cable to it. Just remember to hold on to those tabs. After making your connections to the switch, wrap two or three wraps of electrical tape around the switch and secure it into the box.

You can also replace the existing box with a plastic old work box. The box you pictured won't work unless there's a stud right there to drive those screws into.

  • Yup, came here to say that :) Commented May 31, 2020 at 13:48
  • @Harper-ReinstateMonica Stay safe wherever you are..
    – JACK
    Commented May 31, 2020 at 13:54

Novices sometimes think that metal boxes are a curse because of the chance of shorting against screws. I much disagree: It's easy to insulate the screws as Jack discusses. But if the switch or your splices have a problem, and start making lots of heat due to a poor connection, the metal box will contain a great deal of heat since it's thermally conductive - it'll use the wholebox to dissipate heat. Whereas a plastic box is likely to melt a hole into its side, and leak hot dripping plastic, and even burn if fed sufficiently from arcing heat (it has additives to resist catching/staying on fire on its own).

  • The next installment in Harper's ongoing campaign to restore the honor of the metal box! :D You are 100% correct on what amateurs like me think. Your campaign is working, on me, at least. You've got me rethinking what I may use on my next project.
    – FreeMan
    Commented Jun 4, 2020 at 18:05

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