When you have disconnect boxes (60 amp non-fused disconnect) that surface mount after the drywall is installed for a water heater, an air handler, or similar large appliances that connect to the disconnect panel via whips, what do you do at the electrical rough in stage?

Do you need to have an electrical box installed in the wall behind the disconnect? Do you rough in a mud ring? Or do you just let the Romex stick out where you want it and install the disconnect over the hole in the drywall?

This is electrical rough in for new construction.

2 Answers 2


I would leave sticking out and fixed rigidly sticking straight out a section of MC, for the sheet rocker to know that it needs to stick through the rock. Leave a couple of feet in a tight coil to give you something to work with on trim. On trim I would take a beefy screw driver, stick it into the hole in the wall and pry the straps loose. Then once you connect to the disconnect you can shove the slack back into the wall.

Second method, more difficult. Do the work to get your EMT connector just in the right position sticking through the rock to come. Put a rigid coupling on it for protection and a short nipple of EMT just so the sheet rocker won't miss it. Leave a coil of wire hanging there for the trim. On trim pull off the pipe you don't need and slap on the disconnect.

  • You mentioned EMT and MC in your reply, but I didn't think any conduit or tubing would be required, is that correct? It's just to flag the spot for the sheet rocker, and gets removed? It's just one of these romex clamps that I need to screw into the back of the disconnect in the knock out hole? bexarsupply.com/doc/product_images/detail_623505_usn_tif.jpg
    – Nick
    Nov 2, 2017 at 13:42

It just sticks out. If you want it to look better, you could probably get a flange used for plumbing to cover up the rough in. Make sure to cover the wires though or kill the circuit if it’s on it’s own line.

  • I think you are stating the wire sticks out of the hole, the hole needs large enough for a feed through bushing to protect the wires from the sharp edges of the disconnect box when installed.
    – Ed Beal
    Nov 1, 2017 at 22:48
  • 1
    I understand the question to be, how does the wire terminate through the drywall before going to a disconnect box. Maybe I’m missing something but he’s not specifically concerned with the disconnect installation. Just the correct manner of feeding wire through a hole that will go to a disconnect box. There shouldn’t be a junction box or anything prior to the disconnect. The wiring should go straight to the disconnect.
    – Uggymunkey
    Nov 2, 2017 at 0:37
  • And that is what I said there needs to be a bushing in the back of the box to protect and secure the cable no box is required. Same as running a wire into a service panel. I like Raco brand insider(s) but on larger cables like water heaters will usually use metal 2 screw.
    – Ed Beal
    Nov 2, 2017 at 13:02

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