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I am in the process of installing a subpanel to replace a fuse box in an apartment. My problem is that all the walls are very shallow such that subpanel protrudes about 1 1/2”. It seems all the studs in the wall are framed side way. Can I just install it as is and frame around the panel with molding?

  • Extend the studs on either side of the box to create a chase for the wiring then mount the box with margin beyond stud equal to the finish wall material ie Sheetrock, paneling, plywood etc – Kris Jun 2 at 17:49
  • No problem. Thanks anyway! – Falomany Jun 2 at 18:39
  • Can you post photos of the existing configuration? Also, is breaking the cables out of the wall to feed them into the new panel an option, presuming all the homeruns are in BX/armored cable? – ThreePhaseEel Jun 2 at 21:55
  • Thanks for your interest but I have not started the install yet. I just asked if a panel sticking out of a finished wall is okay. I saw that the wall was quite shallow after opening it up and was concerned about the mismatch in depth of the panel and wall. I can still get by with the number of knockouts that are in the wall cavity. – Falomany Jun 3 at 1:49
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Given the difficulties, you may be better off selecting a panel appropriate for surface mounting.

That would also allow you to get a sufficiently large panel. Panels have been made much larger of late, since wire bending space is now required for large feeders like 2/0. I have 12-space FPE panels barely 8x11, and an 8-space Pushmatic that's 10x12. Those are impossible now. If you are choosing a subpanel that will fit where your fuse box was, forget it. It will force you into an excruciatingly small panel, and you will have to double up circuits. There are several big problems with that.

Multi-wire branch circuits

A MWBC is when two hots share a neutral. They must be configured correctly with each hot on opposite poles, and common shutoff on all the hots. It's probably correct in your old fuse box, but the desperation to cram many circuits into few spaces is sure to cause dangerous mistakes in this area.

You need to pause to identify MWBCs (which share the same neutral). There are two ways to go with these.

  • Merge both hots with a pigtail, and put that on a single breaker screw. (not the 2 lugs of a double-stuff; that would be BAD!) The breaker must be sized for the smallest wire (e.g. 15A for #14 wire). The two hots together can't carry more than 15A, so the neutral can't, making both safe. However, this invites an idiot to see this setup and decide to "upgrade" you by putting both hots on separate breakers.
  • Put both hots on a 2-pole (never a double-stuff) breaker so there is 240V between the hots. This is how MWBCs are intended to work, and it assures the neutral will not overload. It is also clear to installers. A "common maintenance shutoff" is required, but a 2-pole breaker is cheap and readily available.

Statutory requirements

You are now required to have separate circuits for bathroom receptacles, for instance, kitchen countertops, washing machine and several other circuits. Your setup is grandfathered as long as you don't change it. As long as 1 circuit maps to 1 circuit, you are fine. However, let's suppose you combine a bathroom receptacle circuit with a bedroom circuit for lack of breakers. That's a downgrade... you're not allowed to make things worse than they were before.


You might be better off building a "false wall" on top of the thin/narrow wall, and mounting the panel in the false wall. Have it go beyond the panel enough to allow you to get to the knockouts and route wires. You could also mount junction boxes on the false walls, and bring the old wires into the junction boxes, then extend into the new subpanel via attached conduits. You are allowed to splice inside junction boxes.

Even better, you could drywall out the false wall, cut hatches in the drywall, and then cover the hatches with wood trim. Remove the screws to get to the hatches. Mind you, you can't splice in such wall space (fit a junction box for that), but you can access the top and bottom of panel to add circuits.

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You can mount it extending out of the finished wall and trim it out but this will limit the amount of space available for the feeder and branch circuits to enter the panel. As long as you have enough room for the cables and or conduit you could mount it this way.

  • Thanks for your input. And yes, the amount of availabile spaces will be limited. I think I can use y-cable connectors for my bx cables if necessary. – Falomany Jun 2 at 18:23
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    @Falomany Why on earth are you buying a panel with limited spaces? Everyone who does that regrets that, and we warn people loudly and repeatedly here. Get at least a 30 space. The cost differential is quite small and it assures never running out of spaces. Yes, it will take more room than your old fuse box, but that will be true of any modern panel because of Code changes requiring wire bending space inside panels. – Harper Jun 2 at 19:37
  • Harper, Sorry for the misunderstanding. I do have a panel that is much larger than I need. The spaces available that I am talking about are the knockouts for branch circuits that are lined up to the wall cavity. Since about 1/2 of my box is in the wall, I am limited to a certain number of knockouts that are in the wall. A surface box and false wall is out of the question due to the panel location. Thanks for your suggestion anyway. – Falomany Jun 3 at 1:36

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