I just moved to a new house and discovered an outlet on the deck that was not GFCI. The box containing the outlet is waterproof (cover with gasket) but is not deep enough for a GFCI outlet. The box has one 3/4" PVC conduit entering and one 3/4" conduit leaving to another outlet downstream. That makes if difficult but not impossible to change the box, so I decided to go with a GFCI breaker. This circuit only has the two outlets on the deck. I changed the 20 amp breaker to a 20 amp GFCI breaker. I removed the white neutral from the grounding bus and connected it to the breaker along with the black hot wire. I connected the white wire that came with the breaker to the bonding bus. When I try to turn on the GFCI breaker it trips immediately. That means either the breaker is bad or there is a neutral ground fault. While I do not know code, I understand electricity. Nothing is plugged into either outlet. The outlets are cheap 15 amp outlets. I pulled both to make sure they where not back stabbed and they weren't. Is it possible the cheap outlets have a leakage? The conduit also has 6 ga. wires running to a hot tub. The conduit is 1" leaving the panel, and at a junction box, the 6 Ga wires go to the hot tub and the 12 ga. wires (black, white and green) go to the outlets.

When making up plugs on off lengths of wire---I have el-cheapo Chinese, and no marking of any kind. As long as you green ground wire is really on ground---it doesn't matter which wire goes where, does it? With 120v, I don't think you can have reverse polarity. If I need to, I can go back and ohm them out, and make sure which wire goes where.