How do I intall GFCI breaker if wire for outlets is 12/3 using two breakers?

Question

I have kitchen outlets that have one breaker powering the top outlets, and a separate breaker powering the bottom outlets with the tab broke off on each outlet. There are a total of 7 different outlets wired up the same way.

I wanted to have the outlet GFCI protected but did not know how I could use GFCI outlets and have the top of bottom of the outlets be powered but two different breakers. I bought two 20 amp GFCI breakers to change out the original breakers.

That is when I found out that I had one 12/3 wire with black, red, white, and ground wires. I tried to use two different GFCI breakers by trying to wire nut two wires off of the white wire so that I had a white for each GFCI breaker. When I turned on one of the breakers it was fine, but when I turned on the second breaker it tripped both breakers.

I thought that I might have to buy a double pole 20 amp GFCI breaker in my situation to make this work. I am not positive how double pole breakers work.

• Will I then have 240 volts instead of 120?
• Do I have to check every outlet to make sure they did not have black and red on same top or bottom circuit?
• Will I have 20 amps off of each side?

Answer 1

I wanted to have the outlet GFCI protected but did not know how I could use GFCI outlets and have the top of bottom of the outlets be powered but two different breakers.

You can’t make a GFCI receptacle work that way. It can only protect one 120V half-circuit; you have two.

To do this with GFCI receps, you would need seven of them, and each one would be on a different circuit (i.e. both sockets on the same subcircuit).

That is when I found out that I had one 12/3 wire with black, red, white, and ground wires. I tried to use two different GFCI breakers by trying to wire nut two wires off of the white wire so that I had a white for each GFCI breaker. When I turned on one of the breakers it was fine, but when I turned on the second breaker it tripped both breakers.

Yup, that can never possibly work. That is not how GFCIs function. They are comparing the current on the hot to the current on the neutral. If they are different, current is leaking somewhere. So from each individual GFCI’s perspective, current via the other GFCI is a ground fault, and they must trip.

I thought that I might have to buy a double pole 20 amp GFCI breaker in my situation to make this work. I am not positive how double pole breakers work.

Yeah, and I bet you’re getting real sick of spending $100 over and over on things that don’t work. Good reason to ask!

However the 2-pole GFCI is the right solution for this.

A 2-pole GFCI monitors all three wires, assuring the currents are equal (or to be more precise, net out to zero... counting outbound current as equal and opposite to returning current, on whichever wires it may occur). Now, neutral is not bypassing the GFCI so all neutral current is being correctly counted.

By the way, if working with and replacing outlets, never splice the neutral wire on the outlet. Neutral must always be pigtailed.

Answer 2

This sounds like a multi wire branch circuit and putting a GFCI receptacle on one side or even the other tends to have problems unless only the line side s used. Using only the line side and having each receptacle protected by the its own circuitry then alternating from black line to red line is the best way to not have unwanted trips but will be more expensive because of the extra GFCI receptacles required. In most cases it will take 4-6 extra gfi receptacles under 100$ to retro fit many kitchens with no false trips. I have tried to use double pole GFCI breakers and found the best method for GFCI protection on a multi wire with the least trips was each receptacle fed from the line side ether 2 wire or 3 wire both will be protected with maximum protection.