Double-pole, 240-Volt, 15 Amp GFCI circuit breaker to create two 15amp 120 circuits for switched split receptacles. Im trying to figure if i can share a neutral after GFCI dual pole breaker so i can create switched legs for split receptacles down the line. I have red black, green and white in a conduit to an outside box. Can i use a gfci 240 breaker? Will it trip when one leg is switched on or off?
Yes, that's totally fine. What you are proposing is called a multi-wire branch circuit in 120/240 split-phase. They are falling out of favor because protecting them with GFCI or AFCI is a challenge. You must either
- fork the circuit and place AFCI/GFCI after the split; or
- use an expensive 2-pole GFCI device. This is the option you are proposing. And that is fine.
A 2-pole GFCI is built the same as a 1-pole GFCI, it just has 3 wires going around its magnetic sensing core instead of two. All current heading out on L1 must return via either L2 or N. Current flowing out on N must return via L2. Since all 3 wires are wrapped around the magnetic core, each combination causes equal and opposite magnetic flux, which cancel each other out.
After working with 1-pole GFCIs for awhile, ones armchair kneejerk may be to say "that can't work". Take the time to diagram it out and think it through. It works fine.
You cannot share a neutral with individual GFCI circuits. The problem is that a GFCI device measures the flow between the source (hot) conductor and the neutral. If the neutral is shared between two sources, it creates an imbalance in the neutral and trips the GFCI killing the circuits. This is from experience we could never get it to work without running separate neutrals from the GFCI device.