In my bathroom, there is a cabinet against the wall where the original light switch would be. The previous owners ran some romex through the top of the cabinet to a 2 gang box on the outside where the switches now live.

When I went to open the junction inside the cabinet I found out they had just glued the blank plate to the cabinet with some construction adhesive. And behind it, in the 4" void between the original box and the cabinet, is a mess of pigtails.

Does anyone know of a way to extend the original box or put some kind of plate on the front with a knockout so I can run the romex properly and have it contained inside of a proper enclosure? I tried one of these deep-drawn exetension rings but I couldn't find a way to attach it to the original box.

Outside switches

Inside Cabinet

  • What is the actual depth from the old box face to the inner cabinet wall face? – isherwood Nov 7 '18 at 16:48
  • @isherwood the cavity between the wall and the cabinet is 4.5 inches. – Philter Nov 7 '18 at 17:17

You have the right idea but you need a 2 gang switch/outlet box extension. They come in 1/2 increments. I prefer metal but I did see a plastic one on home depot for 3$ the metal ones run 13 to 32$.

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  • Yeah, I had thought about that but the largest extensions I've seen are around 1.5 inches and the cavity between the wall is 4.5 inches so I'd have to buy a bunch of them and figure out a way to fasten them all down to the original box. – Philter Nov 7 '18 at 17:18
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    I'd consider stacking them up and riveting them together. #renegade – isherwood Nov 7 '18 at 17:31
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    Garvin has 2-1/2" 2 gang extensions they call them masonry box extension rings 32.21$ item number tbx-225. I don't see any deeper than that. Wow the photo is deceptive I was thinking it was about 1-1/2" – Ed Beal Nov 7 '18 at 17:48
  • @EdBeal Good find, but for that price, I think isherwood might be right. It may be better to just rivet a few together. – Philter Nov 7 '18 at 18:27
  • I would probably rivet some together also. – Ed Beal Nov 7 '18 at 18:32

I'd go renegade (in the name of good-intentioned improvement) and either:

  1. Install an old-work box in the interior opening. Cut the back of the box off at the appropriate depth to interface with the original box (or fit it inside if that works).

enter image description here

  1. Install a blank cover plate with one or two strain relief clamps in its face.

enter image description here

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  • Do they make blank cover plates with knockouts for plastic boxes? I've only seen the metal ones and they don't fit on the existing boxes. Or are you thinking just cut your own in a blank plastic plate? – Philter Nov 7 '18 at 17:00
  • Nope. Channel your inner carpenter. – isherwood Nov 7 '18 at 17:00

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