I want to feed a sub-panel that is right next to a new main panel I'm installing. I'm putting in a 42 space new main panel, but figured I might as well keep the existing 24 space QO sub-panel next to it. There is only one stud separating the two panels.

What is the best way to feed the sub-panel from this new main panel? Both panels are flush mounted in a 2x4 wood stud wall with drywall. I was thinking that I could go through the sides of both panels (see blue box in picture below)

I'm fine to feed the sub-panel with 50-70A (#8 or #6), whatever I can easily fit through the stud. I was considering a 3/4" by 2" rigid nipple, but I read that you need a locknut on both the inside and outside of each panel (4 total), I don't think I have enough space for a locknut between the panel and the stud. Is there a way to do this through the sides of the panel, or am I better off coming out of the bottom of one panel, go through the stud and in the bottom of the other one?

Thanks! I've learned so much from all the responses I've gotten on my other questions.

Panel layout

  • as well keep the existing 24 space QO sub-panel next to it That does more than the long-term benefit of giving you more total spaces. It also lets you transition a circuit at a time instead of having to do everything at once. Commented Jul 28, 2023 at 21:59
  • Best is subjective, I like threaded rigid couplings through the stud and short chase nipples through the cabinet walls into the coupling. Commented Jul 28, 2023 at 23:24

1 Answer 1


You don't need a locknut on the inside. However, if you don't have them, you can't rely on that conduit as a grounding path.

I would use RMC conduit nipples and conduit nuts.

I would actually do 3-4 passages, high and low, so you can maximize the chance of simply being able to pass wires through, when/if you want to move a branch circuit from one panel to another. To have the best bet of holes lining up, stay in the same manufacturer of panel.

Not a huge fan of that Leviton. I know "plug-on" is fashionable like Barbie, but it's a step downward in safety - plug-on is not as reliable as bolt-on, especially when 2 or more terminals must co-align... so having 4 plug-ons on every breaker is just adding trouble spots. It's not a huge problem (or UL wouldn't list it) but it does happen and we see the reports. Also, their "smart breaker" offerings are disappointing - you can trip a breaker from the app, but must reset by hand. You're also locked into Leviton - on other brands you can use Eaton CL or CHQ, and they do make their Remote Control Breakers in those.

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