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It is possible to install an electrical load center flush mounted (recessed) into a concrete wall? I've seen plenty of junction boxes (outlets) embedded into concrete or masonry but can't find any examples of load centers installed this way, only flush mount installations being between studs. I couldn't find anything regarding concrete or masonry installation in installation instructions or specs. Considering its larger volume I can see how it might cave in or deform in while concrete is poured.

I'd like to do this in a garage where the walls will be concrete but can't think of a reasonable way to connect conduit if the load center is surface mounted.

Edit: Located in WA state so currently NEC 2017 is in force, later this year going to be NEC 2020.

  • What kind of concrete wall are we talking about here? Conventional cast-in-place? Concrete block? ICF of some flavor? This is certainly possible, but does raise its fair share of issues, all the same...and those issues strongly depend on what system you're dealing with here – ThreePhaseEel Jun 8 at 0:48
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    Main issue is that it becomes (nearly) impossible to modify, so you'd want to run LOTS of spare/empty/extra conduits, or you are utterly screwed the first time you need something you didn't install before pouring concrete. This is NOT a minor issue, and probably the main reason it would be very unusual. Structurally, it should be possible with appropriate design of reinforcement steel and/or wall thickness. With a surface mount box, just use the back holes for the conduit you pre-plan and cast-in-place, and the side holes for the ones you need to surface-mount later. – Ecnerwal Jun 8 at 0:49
  • Other approach to connect conduit cast in the walls to a surface box (if your box lacks adequate or useful size back holes) is to stub up outside the box and elbow into it. – Ecnerwal Jun 8 at 0:55
  • Are you planning to cast conduits into the concrete walls? I'm wondering why you're having difficulty with the idea of connecting conduit to a surface mounted loadcenter... – ThreePhaseEel Jun 8 at 1:14
  • These would be conventional poured concrete walls (probably) 8" thick, so a 3/4" Sch40 elbow can fit across (~7") but I'm worried about it 'daylighting' or how to securing in place for the pour. Structurally it can be reinforced like a window - no problem. For future expansion (e.g. EV chargers) it'll be a 200A panel with multiple conduits stubbed out through the top into the ceiling joists. – Serguei Jun 8 at 6:27
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Oh heck no, don't do that.

Imagine you found the perfect house. You love it too, but your partner also made clear that you that you weren't "getting any" except in that house's bedroom. Except, somebody concreted a 12-space FPE Stablok into reinforced concrete, conduits going through it and all. Your insurance company is saying, "If you want insurance, that HAS to go". What sort of choice four-letter words would you have for whoever who thought it was bright idea to concrete that in there in 1983?

Of course there will be no choice. You'll have to stick a new service and panel in an awkward and unsightly place, bypass that panel altogether, and rewire the entire house. And it's made of concrete, so the only way that won't bust the budget is conspicuous Legrand Wiremold all over the walls and ceilings. Thanks loads there, Humphrey!

If there's anything experience teaches us here, it's that changes to service panels are often necessary. Far beyond ordinarily "adding circuits", people have serious problems that require panel replacement.

  • They find out they are dangerous Zinsco or FPE StabLok firestarters, that have to go.
  • They find themselves with a Crouse-Hinds or Pushmatic that is inherently obsolete and simply cannot meet today's standards.
  • It doesn't have those problems, but it's a dangerous "Split Bus/Rule of Six" panel (which, granted, can be solved by subpaneling if the service wires are in conduit).
  • They don't have enough spaces, because the same genius who set it in concrete also picked a 16-space panel. "But it's 32 circuits!" which buys you nothing in NEC 2020.

Of course, that's what we know today about 1980's panels. What will we know tomorrow about today's panels? Will we find out that Square D HOM's relatively young plug-on neutral scheme is as dangerous as FPE/Zinsco? Will GE drop all support for older panels (again) just as JFCI breakers become mandatory? We don't know. That's the point.

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  • Worst case the cast-in-place conduit/boxes can be abandoned, maybe grouted up, and building rewired with surface mount conduit/boxes? – Serguei Jun 8 at 6:06
  • Should mention: this is for a detached 20x30 garage. I plan to use a 40-60 space 200A panel (for a couple EV chargers in the future). If more than that is needed it's likely a demolition project at that point :) – Serguei Jun 8 at 7:09

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