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I'm framing up an office inside a warehouse using 2x4 lumber. There is a framed wall against an existing side wall of the warehouse. Along the existing wall is conduit and two boxes with receptacles. I was going to remove the entire thing, but one of these boxes is also a junction box that leads to the lighting. I need to remove at least one of the boxes (because it's in the way of a stud), and so I'd like to run new wire through the new framed wall (NM).

However, I'm not sure how to transition (any of) the wiring from the panel at the back wall (which will not have a new framed wall around it) to the new framed walls.

The run to the lighting connects here:

Conduit to lights

Here you can see where the conduit continues to the panel, and the box that needs to be removed. I need to build a last framed wall section in that corner, but the conduit is in the way (I don't want to notch the studs, particularly the last stud).

How can I run NM through the studs and properly transition to connect to the panel?

Conduit to panel

Note: as I understand it, I can't have receptacles in the wall like that, so I'll be removing it and replacing the junction box with a cover. But it's still not accessible once drywalled, so I'm not sure if that's to code or not.

  • What construction type is the building, and are you OK with some sort of armored or metal-clad cable instead of NM? – ThreePhaseEel Nov 26 '17 at 5:52
  • No, you can't drywall over any junction box, even if the cover is blank. So either do what Victorians do with tub valves and put a little cabinet door there... Or remove the box entirely and straight-pipe through that conduit location. If something is exiting out the back of that box into the wall, you're in trouble! You can't even cover up a conduit body. Find a way to do it with curved pipe. – Harper Nov 26 '17 at 6:15
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    Also does your local code allow NM in commercial? NM isn't legal in homes because of wood construction, it's legal because they're residential. – Harper Nov 26 '17 at 6:19
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    I would just reiterate others' comments. In most commercial locations, NM cable is not allowed unless it is in a raceway and that would be redundant. Another option is ENT. You should check with your local electrical inspector for options that are allowed in your location. – ArchonOSX Nov 26 '17 at 11:36
  • Commercial projects are off topic – mmathis Nov 26 '17 at 21:19
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"In the way of a stud" implies a heck of a lot more stud consistency than is actually required in a (pretty clearly) non-load-bearing wall, for one thing. But if you feel you must, if there's no wire into the wall from that box, you can reposition the box by pulling out the wire, cutting the conduit and using a conduit coupling to shift the position of the box along the conduit by the amount you cut off. Of course, at that point you need new wires on whichever side got longer in that event, since you would otherwise need an accessible junction box where the box you want to move was.

NM cable is generally not allowed in commercial, for another.

And junction boxes cannot be covered up, period. They can, however, be extended to the face of the wall (look at box extension rings, they clip to the box like a cover at one end, and take the box cover at the other end. Alternatively, there are standard access panels to install in drywall and give more working room (if the wires won't come out to the face of an extended box, you once again need new longer wires that will. A panel makes the original non-extended box accessible.)

Personally, I'd suggest getting comfortable with bending EMT - it's not hard, and it's got some advantages over MC in my opinion (you can pull wires as needed, for the most obvious point.) MC may be an easier concept if you think like NM but need to work commercial, but in many cases EMT will also come out cheaper all told.

  • I never planned to cover the junction box. I ended up removing the conduit entirely, mounting a junction box to the stud by the end box, pulling the MC that went into that box from behind the existing wall into it, and then running MC on the existing wall up and over the new construction, and into the panel. I'm not sure if there's a length limit to how far MC can be run. Pity about NM in commercial; didn't know that, thank you. How does one get conduit into studs? Short sections? Notching? – Rick Nov 27 '17 at 7:26
  • And yeah, I hate it when studs are off. I plan to mount a lot of cabinets and shelving inside the office when it's finished (part of the reason I went with wood and not metal studs). – Rick Nov 27 '17 at 7:28
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    As I think about this more, it occurs to me I can run EMT from my outlets and switches vertically up past the top of the new construction, and into junction boxes. Then I can run EMT horizontally above all the new construction, and avoid running it through the stud wall. Is there a recommended product for the horizontal run (like a Wiremold wall-mount raceway, but that would be overkill)? I suppose 1" EMT horizontally to regular junction boxes will probably be fine. – Rick Nov 27 '17 at 9:05
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Remove some of the conduit or all the conduit and replace it with MC cable. Replace the boxes where you can easily. On the box or boxes that must stay, install extension rings and mud rings to bring flush with outer surface of finished sheet rock. After wall is painted trim as normal. At the panel to start the run, if need be, install a piece of 1/2" EMT from the panel and bend it to enter the open stud wall and terminate in the middle, both ways, of the stud bay. Finish the termination with a 1/2" SS connector and a 1/2" GRC coupling. Put an MC connector into the GRC coupling. Strip sufficient extra jacket off the MC to allow the conductors to reach well into the panel. Use 12-3 if necessary. Still short on conductors, make two runs from the panel.

  • I ended up doing basically this, although I mounted a new box on the new construction instead of just bringing it forward with a mud ring. – Rick Nov 27 '17 at 18:28
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You can do as @Paul Logan suggested or you can cut your EMT back, mount the 4 sq box flush with the stud and add a plaster ring for the thickness of your drywall and finish. You can make a transition with a EMT to Flex adapter or build one out of an EMT connector, A threaded coupling and a flex connector. Then make a transition from EMT to flex and connect it to the box. Keep the flex under 3 feet.

If you want to run more devices than just the one shown then I would continue with MC just as @Paul Logan suggested.

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