I recently swapped out a 40 amp breaker (previously for an oven/range) to a 30 amp GFCI, on the other end will be a L6-30 receptacle (2 hots, 1 ground). My question is what to do with the neutral wire on either end of the line. In the panel, is it correct to connect both the neutral from the line and the neutral pigtail from the breaker to the neutral bar, leave the neutral terminal on the breaker empty, and then cap the neutral at the receptacle? Or should the neutral from the line be connected to the neutral terminal on the breaker?

Through some research I think I found that GFCI only needs the neutral for 120v loads, just not completely sure

  • I have a 20A, 240V GFCI breaker in my barn. It came with a neutral (white) pigtail, which I connected to the neutral bus in the breaker panel. I believe it needs that to power its internal circuitry. Otherwise there would be no reason to have the white wire pigtail at all. So my thinking is that if your breaker has a white pigtail, you should connect it to the neutral in the breaker box. What should you do with the white wire leading from breaker box to outlet? I think leave it connected in the breaker box and cap it off in the outlet box. That is what I would do, but I am not an electrician. – mkeith Feb 15 '19 at 3:19
  • I take it the cable is a 4-wire cable (hot/hot/neutral/ground)? – ThreePhaseEel Feb 15 '19 at 4:49

You connect the 2 hot wires to the breaker like you would on any other double-pole breaker. You also must connect the pigtail from the breaker to the load center neutral terminals. Connect the ground wire from the circuit to the load center ground terminals. The neutral terminal on the breaker is just unused in this case.

See for example this diagram from Square D instructions:

Wiring Diagram

But certainly make sure to check the instructions included with your specific breaker. If you don't have them, I've had good luck finding instructions on the home improvement store websites - seems like they are easier to navigate than the manufacturer websites.

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We recently had a very interesting discussion with a person applying North American GFCI breakers in the Philippines, where power and loads are 240V-only center ground. It turns out north American GFCIs require 120/240V for their own internal loads; capping off the neutral pigtail did not work at all.

There were good reasons not to rely on ground as a current return, so that person installed a tiny 240V/120V autotransformer to supply midpoint "neutral" for the GFCI's inner workings. After that, they powered right up and cheerfully served the 240V-only loads.

So yes, you need to attach the neutral pigtail on the LINE side of the GFCI, but you do not need to attach anything to the neutral LOAD side.

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