TxGearhead wrote:
Ok. Earth ground through the jack makes good sense.
Yep. If you have the camper 7pin plugged into your truck then the truck will have a ground via that jack being down...
If the jack is not down and you were plugged into shore power and something happened that the shore power ground in the camper had a "leak" then the truck would become "Hot with the leak". Touch the truck and get a "BITE", shock.
I have encountered this situation on some folks metal trailers and other RV's. Touch the door handle and get a "BITE".... Fixed a few for folks.
Jim