X2.... the trailer has an issue somewhere in the wiring where the neutral is touching the ground somewhere. Basically, a ground is only a "safety" circuit and should not be "seeing" anything if things are OK (that's why
GFI's works). The likely reason the poster seemed to indicated that the problen "went away" when moved to another pedestal was that pedestal probably had a good ground going to it so it didn't mind "absorbing" things and thus the "shocking feeling" went away. It didn't solve the likely actual problem... which reversing the wiring will potentially not solve either depending on what actually was rewired.