Wiring – Double-pole, 240-Volt, 15 Amp GFCI circuit breaker to create two 15amp 120 circuits for switched split receptacles

gfciwiring

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?

Best Answer

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.