How do you install electric outlets on both sides of a 2"x4" interior wall to meet code? The back of each box (and wires entering box) is very close (less than 1/2") to the front of the other side of the wall. Is there code on how to do this?

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    Hello, and welcome to Stack Exchange. Where are you located? Commented Nov 25, 2018 at 0:00

1 Answer 1


I'd use 4x4 boxes that are 1-1/2" deep with single gang raised mud rings. These will give you plenty of room inside.

Feeding through the backs of the boxes with a nipple sounds easy but will turn out to be a pain. Better to just feed bottom to bottom with a short romex jumper.

  • Any reason you don't use 120mm boxes instead of 100mm for this? Commented Nov 25, 2018 at 4:25
  • @ThreePhaseEel - no, no reason, 4x4 is just my default box, do you prefer the 411? Commented Nov 25, 2018 at 9:33
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    I'd use a 5" or larger even if you could get them in such a shallow depth -- you can never have enough box space ;) Commented Nov 25, 2018 at 15:13
  • @ThreePhaseEel it's fine to do, but I don't generally stock 120mm boxes (4-11/16") that are shallow enough. When I use them I am all about the cubic inches, so I buy deep 120s. Commented Nov 25, 2018 at 16:27
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    Got it! 2 x 1.5" deep boxes = 3" which leaves a small gap between them when back-to-back in the wall. The mud rings get them to the surface and give a smidge more room for wiring.
    – FreeMan
    Commented Nov 27, 2018 at 18:49

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