? for a Master Electrician

I wired my father’s dock a few weeks ago and I’m having problems with the 30amp 2 pole gfci breaker. the gfci is in the main panel in the garage. the panel is 4 wire, the pre wire from the panel to the back of the house is 4 wire to a bell box. i ran a 10-3 uf to the dock for a 6/12 square d rain tight panel. from there i ran 2 snook lights (halogen spots) on a photo cell and a quad receptacle. also pre wired was a switch leg from the house to the bell box. i ran a 12/2 uf for the switch leg for the post light and made a junction in the dock panel for the switch leg landing the neutrals on the neutral bus. i put a 1 pole 20 in the dock panel for the snook lights and the quad receptacles. the gfci breaker will hold if the 1/20 at the dock panel is off but when i turn the 1/20 at the dock on the gfci will trip. the instructions say not to have a load run over 250ft. it’s not. instructions also say not to use the gfci for electronics. it also gives instructions for a 3 wire application that i followed.
i un hooked the photo cell and the problem still exsists. the only thing i havent tried was to remove the neutral from the switch leg light from the house off the neutral bus and junction it with wire nuts instead.
i know there are a few brilliant electricians on this forum who may shed some light on this problem of mine.
thanks for any and all responces and help!

I’m not an electro-guru but my guess is a simple short somewhere. Something sufficient to blow a 30A breaker sounds to me like a dead short, either hot to neutral or hot to grnd.

John Kogel

Maybe the GFCI is doing its job. . .

Does the switch leg from the house get its power from the house or does it back feed from the dock panel? If the switch leg gets its power from the house the neutral with the house circuit needs to be isolated from the dock panel neutral. I don’t think you need a gfci breaker for the dock panel, just a gfci breaker for receptacles feed from the dock panel or the receptacle can be gfci type.

LOL too funny Jeff :wink:

Jason do you have any pics of the panels, I’m having trouble visualizing it?



I’m thinking a neutral issues somewhere causing the GFI to trip.
Gary might be one to something.

Does not the load on a two pole GFCI breaker have to be balanced from pole to pole?
Can a two pole GFCI be used to feed two separate 120 volt loads?

See pages 136-7 of Commercial Electrical Wiring at:


it’s not a dead short because a standard 2 pole 30 will do the job fine but when replaced with the gfcc it will not hold.

the reason for the dock panel to be gfci was a request from my dad, he said there have been a few electricutions of people on thier boat lifts in his area.

i hope it’s just that the neutral from the switch leg needs to be removed from the bus and just junctioned by a wire nut.

Let us know if it works after removing the neutral. I think that’s the answer.