First off, I usually run all the wiring then hire an electrician to make the final connections simply because I have no confidence in my electrical abilities. One thing that seems suspect is the ground rod. The generator doesn't require one so maybe this is what is causing you trouble with the GFCI.

I've noticed that when I plug my worm wand into a GFCI outlet, it pops as soon as I touch the soil. Doesn't seem to bother a 15 amp breaker though.



"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking