A whirlpool bathtub requires two 20A circuits. Can I use a two-pole GFI breaker and a 12/3 cable to power this?

I know there can be problems with GFI and MWBC but I don't think I would have those problems here. Single hard wired device on each branch. If either pops so will the other ... that's fine.

I know a duplex GFI breaker is expensive, but it's a long and torturous cable run so it make sense for me to use a /3 if I can.

  • 12/2/2 cables exist that can take 2 separate circuits in a single cable. So you aren't limited to MWBC on a 12/3. May 5, 2022 at 16:41
  • 12/2/2 is extremely hard to find right now, and in retail (single-project) quantities is crazy expensive. It's a good comment and worth considering, but having considered it I'll keep the scope of the question as is.
    – jay613
    May 5, 2022 at 16:57
  • They also sell two to four 12/2 cables lashed together with tape. "Some assembly required" May 5, 2022 at 18:49

1 Answer 1


You can do that. Most "problems with GFCI & MWBC" are from not using a two-pole GFCI breaker to feed an MWBC.

You can also use a regular double-pole breaker and 12/3 to the point where you split to two receptacles, and put the GFCIs there. Then the GFCI's don't see the MWBC as they are beyond it. The only thing the GFCI breaker buys you is the ability to put them both on one 20A duplex outlet with the hot tab broken.

Ah, hard-wired. Yeah, perhaps the GFCI breaker is better, then.

  • Thanks for the added suggestion. I'll see if the tub has a plug-in option and could save some money if it does.
    – jay613
    May 5, 2022 at 16:25
  • I envision potential issues with having them accessible for resetting if what's being powered is "stuff underneath the bathtub."
    – Ecnerwal
    May 5, 2022 at 16:28
  • I was going to say that myself ... just go with the GFI breaker .... but then I thought if the breaker pops I'll almost certainly want to look under the tub anyway. I suppose a future owner less technically inclined than me might like the ability to reset the breaker, if that happens to work, without climbing under. Ya, that actually decides it for me. For an extra $50 now, the next guy doesn't have to call someone for a nuisance trip.
    – jay613
    May 5, 2022 at 16:37
  • I installed the breaker, and getting frequent nuisance pops in a test configuration with a few lights. Follow up question here
    – jay613
    May 12, 2022 at 14:49

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