I added a GFI outlet to a dock panel that is wired for my boat lift. The boat lift motors are wired with a GFCI outlet located in a sub panel that is on the back of my house.

2 hot wires (for 220v) and a neutral wire come from a GFCI breaker in the house-mounted panel and are run in conduit to the dock panel. Also in the conduit is a ground wire and a third hot wire (to be used for the dock GFCI outlet) The third hot wire comes from a separate non GFCI breaker in the subpanel. . I mistakenly thought I could add a GFCI outlet to the dock after the fact by sharing the neutral hat is used for the motors. Now of course when both circuits are powered at the same time both GFCI’s fault. I get around it now by only using one circuit at a time which is not an issue for me but I would like to have it right.

It is not practical to run a separate neutral down to the dock since the existing 80’ of conduit is full and will not accept another wire. Is there a way to make this work maybe by isolating the neutral down in the dock mounted panel?

Any help would be appreciated.

1 Answer 1


If the boat lift motors are, or are replaced with (or rewired as, if convertible voltage) 240V motors, the 240V GFCI has no need of any neutral wire connected to it, and the neutral wire can be repurposed to (only) the 120V GFCI outlet.

There's no way to "share" a neutral between two GFCIs, and "sharing" a neutral between two circuits is a very clear code violation with the potential of overheating the wire.

Since you've given no details of the size of conduit or wiring, no comment is possible on the fullness of the conduit. Either you're correct that it is full, or not. In many cases a not-full conduit that you can't just pull an additional wire into can have the additional wire added if you pull all the other wires out, and add the additional wire and pull them all back in; but you can only do that if the actual resulting conduit fill will be less than or equal to 40%.

  • Thanks for the response Ecnerwal. I have come to the same conclusion. The motors can be rewired without the neutral according to the manuafacturer. Then use the neutral for the GFCI outlet.
    – Phil Niemi
    Jan 5 at 10:06

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