I know similar questions to this have been asked before, but I haven't been able to figure out the answers to some of these questions.

First an explanation of the situation, the main 200 amp panel is in the two car garage (house built in mid to late 90s in the eastern US). The panel is immediately to the left when you enter the main garage door from outside. This wall is also unfinished. The back wall of the garage leads to the house and is one edge of the also unfinished basement:

Layout of garage and basement

The estimated run is about 45 feet or so, and the purpose of the panel is to have a small wood/maker shop in the basement. I would like to run the cable through the unfinished wall and then add rock wool insulation and close up the wall later.

The equipment I am expecting to run:

  1. dust collector (harbor freight)
  2. shop vac
  3. CNC router (shapeoko 3)
  4. miter saw
  5. some LED lighting
  6. wall outlets (4x 20amp probably)
  7. air cleaner
  8. 3D printers (4~5)
  9. Laser cutter (future)
  10. plasma cutter (future)

I think around 60 amp should be enough for my usage as not everything will run all at the same time, especially not the things that draw the most current will be in use in parallel usually. I think a 12 spaces 125 amp panel should be more than enough for my usage well into the future.

Now based on the research that I have done so far, here are my questions:

  1. Is 2-2-2-4 SER cable the correct cable for this? I am hoping to protect this panel off a 60 amp breaker but would like to leave some room for growth without requiring a complete rewire.
  2. I am not sure if its permissible to run SER cable through the wall as even though I could add nail strips on the interior of the garage to protect it. The outside already have vinyl siding installed and I have no way to protect that side for future.
  3. What is the max size hole that I can put in 2x4 on the exterior wall for running such a cable? I have seen posts saying up to 40% of the width which on a 2x4 is about 1 3/8?

Eventually I would like to finish off the garage and the basement after this install, the only other thing is to run an airline for the compressor from the garage to the basement.

Please let me know your thoughts and what you would recommend or any gotchas that I should watch out for?

I plan on having this work inspected and permitted, but my county requires all electrical work to be done by a master electrician or for the home owners to pass a test on NFPA 70 before even applying for a permit. They give you the NFPA 70 code during the test, so hopefully it shouldn't be too hard.

Anyway, thanks in advance for your help and reading this whole post.

  • Check with your county for the hole sizes in studs, if they are that hard on electrical work, building work might be as hard. Reading the code and answering questions on the code can be different, some of it will be comprehension of what the code means. A nice electrician will allow you to do the dirty/hard work as they watch, hopefully with a reduction of their costs.
    – crip659
    May 10, 2023 at 23:31
  • I would start with getting a Quote for the job. Now you know and can compare to getting NFPA 70e, which is not free and time consuming.
    – Traveler
    May 10, 2023 at 23:43

1 Answer 1


I'd recommend conduit and wires, not cable.

If you choose non-flexible metallic conduit, and assemble it correctly, you have your required ground without a separate grounding wire.

Given it's a garage, not a living room, I'd simplify life and run the metallic conduit (probably EMT) on the surface of the wall, not through the studs. Garages can be functional, even if they get some drywall eventually. You can run it up near the ceiling if you have appearance concerns and slap some crown molding on there if you're overly concerned with appearances. Or put it down next to the foundation if the foundation wall juts out from the 2x4 wall there.

The typical "cut and paste" code language for boring holes in studs in bearing walls is 40%, no closer than 5/8" to the edge, not where the stud is also notched or bored with another hole - which does come out 1-3/8" for 2x4 studs. If running cable through holes, 2-2-2-4 SER should just fit through a 1" hole, perhaps 1-1/8 to make it easier. Don't knee-jerk to the largest hole you are allowed to make. Keep the holes properly centered in the stud and you don't need protective plates, because you're supposed to know not to use huge screws or nails into walls. SER should be OK in your walls if you choose to use it.

I would strongly recommend not limiting yourself with a 12 space panel. The price differential to bump up to 20+ spaces is trivial. The hassle when you run out of spaces due to things you didn't think of when is huge.

As for the homeowner code test, they will be trying to trip you up with things that are hard to find if you don't know where in the (rather large) code book to look, and things that calculate out just over the limits, commonly. 40.01A is not "basically 40A" in NEC land, it's 50 (for wire, breaker sizing - derating, etc.)

  • Thanks for your answer, what size wire would I use with EMT or is the 2-2-2-4 SER cable good to run through the EMT conduit?
    – xero
    May 11, 2023 at 12:15
  • AWG 2 AL (3 wires, not cable - cable is a #$@!%&! to pull through conduit, compared to individual wires, and you don't need a ground, but AWG 4 AL or AWG 8 Cu (because you might go to 90A someday) if you are one of those people that doesn't trust code on conduit being ground. 1-1/4" EMT should fit. 1" will JUST fit (39.9% fill) if you use conduit as ground & get XHHW rather than THHN wires (40.31%.) THHN requires 1-1/4 and would be a much easier pull at 23.15% fill (22.92% for XHHW, also a much easier pull than 39.9%)
    – Ecnerwal
    May 11, 2023 at 12:48

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