I have a 2-pole 30amp breaker which feeds a multi-branch circuit consisting of 2x L5-30R's. I was wondering if there are any issues with running a 120v 30amp UPS on one of the L5-30R's? The other L5-30R would be feeding a standard 30amp PDU.

I just want to make sure the smarts in the UPS won't flipout because of the multi-branch circuit.

UPS: https://www.cyberpowersystems.com/product/ups/new-smart-app-sinewave/pr3000rt2un/

1 Answer 1


The UPS has no way of knowing if it's on a MWBC or not. Once you get down to a 120V feed, it looks the same from the receptacle.

Therefore, the UPS can't see anything to flip out about.

  • Thanks! I was worried about the shared neutral and any issues the could arise there.
    – umhelp
    May 1, 2021 at 19:15
  • 1
    That'll only be a problem if the neutral breaks. In that case, the UPS may be helpful, because it'll see (its) voltage deviate significantly from 120V, and it will disconnect, protecting whatever is on the other leg. May 1, 2021 at 20:25

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