I'm assisting a friend in adding a solarium using a partially existing room. The room formally housed a hot tub so rather than run new wiring, we decided to use the 50 amp breaker and line that was in place and we added a 6 breaker sub panel. By the way, for the record, I'm not a novice when it comes to residential wiring. Here's my problem. I want to run a string of recepticles off of one GFCI so I ran the #12 wire using a 20 amp breaker to the first box. Simple, right? Wrong. The recepticle is only about 2 feet from the sub-panel and when I put the GFCI in and turn on the power the reset on the GFCI immediately pops and won't reset. From the sub-panel to the recepticle, everything is right. Any ideas? I know the GFCI will trip with a neutral short so is it possible that another recepticle in the house has the common and "hot reversed backfeeding through the box. Help, I'm stumped.