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I have NM cable in metal conduit running along a wall. At a corner, the conduit enters wall space, and ends at a metal box in the wall. The line is continued by in-wall NM. How should I handle the point where the conduit enters the wall? Just a hole in the sheetrock?

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    You write as though all the conduit already exists. Are you just installing it now? – isherwood Jan 4 '16 at 18:25
  • Normally you'd use a j-box, which allows a fairly tight bend with a tidy hole. i.ebayimg.com/00/s/NzY4WDEwMjQ=/z/GFMAAOxyQj9RS1PL/… – isherwood Jan 4 '16 at 18:28
  • @isherwood -- there are LBs, LRs, and LLs, but no LF conduit bodies, sadly -- as a LF body with a volume marking would be perfect for this application. – ThreePhaseEel Jan 6 '16 at 2:38
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It sounds like you're sheetrocking over the existing wiring. If that's correct, I think this would work. The challenge is you want to make the transition from conduit to plain NM in a box, and you want the plain NM concealed inside a wall, not out in the open where it's exposed to damage.

  • remove the box from the end of the conduit
  • install two boxes in the face of the new wall, maybe one at switch or sconce height, one at receptacle height. (These boxes will be accessible through the new sheetrock.)
  • Cut the existing NM mid way between the new boxes
  • extend the conduit to the upper box (with the NM in it)
  • splice in a new piece of NM from the upper box to the lower box
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One option would be to use a 1-gang box in the wall getting sheetrocked with a matching faceplate that has a suitably sized conduit knockout in it. You can then connect to the box and faceplate normally, although getting it apart again can be a trifle tricky in such configurations, as such faceplates normally are used to fit MC, FMC, or LFMC whips as opposed to rigid conduit.

Example image (from the Home Depot catalog, although I can't find the product on their website any longer):

Metal 1-gang faceplate with a conduit knockout in it

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Yep, just pop a hole & compound, caulk or a snug rubber grommet. The conduit is just to protect the wire from being easily or accidentally nicked, the wall takes over that duty & the transition can be as pretty or ugly as you want...by Code.

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    But you can't bury the box behind the sheetrock... – batsplatsterson Jan 4 '16 at 20:13
  • Yeah, I'm hoping he's meaning it's correctly installed with a surface cover plate & not buried "in" the wall. Though, those are "fun" to find if you're looking for more work & pay. – Iggy Jan 4 '16 at 23:26
  • @batsplatsterson If there's no actual splicing of the cable happening (so just NM in conduit leaves the conduit), I don't think it needs to happen in a box. Unless there's explosion or water protection needed. – Someone Somewhere May 5 '16 at 8:16

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