I need to replace two receptacles in my kitchen with GFCI outlets. On each receptacle, the top and bottom outlet are on different breakers. I've replaced standard outlets before, but this seems a bit more complicated.


The A outlets are on one breaker, and B is on a different.

An electrician once told me (several months ago before i was ready to do this project) that I could just cap the red wire on the left and the black wire on the right. Not sure I quite remember what that means.

These load to other outlets as well. Any thoughts on how I can replace these with GFCI? Thanks!

2 Answers 2


You have what is known as a "multi-wire branch circuit", where two otherwise independent circuits share the same neutral return back to the electrical panel. Wiring the GFCIs in a naive manner won't help you here, because in a shared neutral situation, the GFCIs won't see the return currents coming back from the "other" hot wire, and will trip as they are designed to do as a result. However, there are two options to rectify this, depending on your situation:

1. Replace the breakers with a two-pole GFCI circuit breaker

Depending on the make and model of your electrical panel, you may be able to obtain a two-pole GFCI circuit breaker for it; in that case, and if your kitchen circuits come from adjacent breaker slots in the panel, you can replace the kitchen circuit breakers with a single two-pole GFCI breaker and get GFCI protection without rewiring the outlets.

2. Install GFCI receptacles so that each receptacle device is on a different leg.

Right now, you have what's called a "mixed leg" shared neutral circuit, where both legs are present at each receptacle device, instead of having half the receptacle devices attached to one leg and half to the other. However, you'd have to pull a 12/2/2 instead of your current 12/3 for all devices attached downstream of the first GFCI, or retrofit all outlets on this circuit to be GFCI outlets, which is undesirable.

Borrowing a diagram from this answer by Tester101:

GFCI wiring on a shared neutral

  • You could easily just have every outlet that needs to be GFCI protected be a GFCI outlet with no downstream outlets. Mar 27, 2015 at 0:38
  • @BradGilbert -- I mentioned that option already -- it's undesirable because then you have to buy a gajillion GFCIs. Mar 27, 2015 at 2:37

I had the same problem but since I didn’t need 2 curcuits at the outlet, which the GFCI was to be installed, I capped the wires feeding that side of the outlet. I did connect the GFCI so that half of the downstream outlet was also protected.


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