Long time reader first time post.

I recently installed a 100 amp sub-panel from my 200 amp service to a barn on my property. It’s been a few months and now I’m finding that I actually should have installed the sub-panel in my detached garage that is near the barn. So, I’m wondering how would I go about adding a sub-panel with power coming from the sub-panel in the barn. I'm thinking 50 amps is plenty for this second sub-panel and would never run anything heavy on amps in both the barn and garage at the same time.

Can this be done? If so is the drawing correct with regards to wiring? I used a main panel in the barn so that I could have a main disconnect which would allow me shut off power in the barn. I believe it's required in a detached building.

enter image description here Thanks

  • The sun panels should not be bonded past the main breaker…am I wrong. That would make the sketch incorrect.
    – Ryan
    Nov 27, 2022 at 5:17
  • @Ryan What are you talking about specifically? The diagram shows the neutral bars in the sub-panels isolated, and the ground bars attached to the metal panel boxes - everything exactly as it should be.
    – nobody
    Nov 27, 2022 at 22:44

1 Answer 1


looks like you have it correct 125% of 50 is 62.5 so you should use #6 wire

  • What's the 125% for?
    – Tester101
    Nov 10, 2015 at 20:46
  • 125% of your breaker is the wire size for the feed to the 2nd sub.
    – Ed Beal
    Nov 10, 2015 at 21:30
  • Says who? Where are you getting that from?
    – Tester101
    Nov 10, 2015 at 21:31
  • this is a feeder 215-2.-1 ,210-20A, 215.3 the over current protection device is the maximum load then add 125% to protect the wires
    – Ed Beal
    Nov 10, 2015 at 21:46
  • 1
    OP may not be in Oregon, so Oregon amendments may not be applicable. It's best to stick to what NEC says, and let the OP worry about local amendments.
    – Tester101
    Nov 11, 2015 at 15:18

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