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How do I install a GFCI receptacle with two hot wires and common neutral?

I have a pool to protect correctly. There is a 12/3 wire: red serves the receptacles at the bottom of the pole lights and the black serves the pole lights. Now they are on two separate breakers. I was going to put a single pole GFCI on the receptacle line but I know that I can't share the neutral.

I see 3 options:

  1. Can I put both the red and black on the same single pole? I think it is against code but would it work? I don't need the 20A for lights and the outlets.

  2. Is the double pole option with the single ground right?

  3. Wire the first outlet in the series with a GFCI .... but I'm not sure that works because the pole lights after it again share the same neutral.

I'm not pulling new wire ... It's underground.

  • See this question on GFCI challenges related to wiring in the home with a shared neutral.
    – BMitch
    Commented Aug 5, 2012 at 22:47
  • Can you explain #2? I'm not sure how to parse it.
    – Jay Bazuzi
    Commented Aug 6, 2012 at 2:15
  • You could put a subpanel at the pool. Always the best option!
    – Jay Bazuzi
    Commented Aug 6, 2012 at 2:17
  • Is a double pole GFCI breaker an option?
    – Tester101
    Commented Aug 6, 2012 at 11:53

1 Answer 1


If you are asking if you can double tap the breaker in the panel (#1), the answer is no.

GFCI Breaker

My first thought in this situation, would be to use a 20 Amp double pole GFCI breaker.

enter image description here

These tend to be quite expensive, but it will protect both legs of your circuit.

Single GFCI Receptacle

The next option would be to install a single GFCI receptacle to protect all the downstream receptacles, and leave the lights unprotected. Though you'd have to check your local codes to know if the lights need to be protected.

enter image description here

Just remember, you'll have to pigtail the neutral before the GFCI receptacle for this to work.

Two GFCI receptacles

The other option is to install a GFCI receptacle to protect downstream receptacles, then install another GFCI receptacle to protect the lights.

enter image description here

Again, you'll have to pigtail the neutral before the first GFCI receptacle. This also has the disadvantage of having a receptacle on the light circuit, which can lead to overloading the circuit and standing in the dark because of it. However, it does insure both legs of the circuit are protected. You could install the GFCI receptacle that protects the lights in an inconvenient location (while still keeping it accessible for resets/tests), to limit the temptation to use it.

Remember to check all local codes and regulations before doing any work, and never be afraid to call an Electrician if you feel uncomfortable at all during the installation.

  • Thanks, I appreciate the answers. I do not want to mess with more recepticals etc outside and I will error on the safe side and protect the lights. Luckily the two current breakers are beside each other in the box so I will go with the double pole 20A at $90 +/-.
    – RJH
    Commented Aug 10, 2012 at 1:17
  • 1
    To add to the "two GFCI outlet" option, they do make GFCI outlets that are "blank" with no actual outlet receptacle. This is useful in a case where you may want to protect a load (such as lights or a vent fan in a shower) but not connect it to a live receptacle.
    – Thomas
    Commented May 18, 2018 at 7:57

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