[jimcol]

I had that happen once when I touched the hub of one of the wheels. The source was a burnt up electric heat element in the water heater. Lesson learned, "Never have the element on with the tank empty." The dealer had just gone over that with us about two hours before during the PDI. It's been 16 years ago but if memory serves me correct I was powering the trailer via a non-grounded extension cord.