Thanks for the tip Lefty, you still got the touch! Old Man???
Yep, one day older than water...two days older than dirt. Looks like all that $$$ that the Army spent on training me might have been worth it.
My old Airstream taught me the one jack on the ground trick. I can't count on the grounds on the pedestal to be good. Having the jack on the ground just provides another path to earth. Better the trailer frame/jack provide a return rather than this old body.
GFI's are leakage based and are supposed to trip long before the current reaches lethal levels. Because the ground is no good, your body or whatever was providing a better return to ground. Your trailer is really the first place that I've seen the GFI be anything other than a source of problem. I'd say yours works.
Electricity is a funny thing. Ground loops, high resistance shorts...At Ft Huachuca, the grounds are terrible. Because of the dirt and dryness. I could take a voltmeter, put one end on a grounded frame rack and the other end on the metal mesh security screens....and during a lightening storm the old voltmeter would read 12 volts!
They don't call voltage "potential" for nothing.
Just TRY to wash an Airstream while it's plugged in and have the ground at the pedestal be bad. You'll find out that electron flow is MORE than a theory!
The language used was not for women and young children!!! Knocked me down..smoke rolled from my pacemaker!!
Thanks heavens for fiberglass siding.