Hartwell and others:

I have more than once been in a park, hooked up and either had no power or a reading on my little gizmo that I had a faulty ground.

It seemed that in most cases, the box outlet had been overheated by sustained maximum (or more) draw on the 30 amp supply -- or that it was the fault of the male plug from the RV. I do know that I got scolded for having dirty contacts, corrosion around the wirng, etc. (I then bought a new male plug, replacing the offender which I had noticed got very hot but afterward stayed cool.) I was accused of causing the outlet problem--I had been there for a long time. That was at Top of Georgia, and the problem was somewhat widespread because "no one keeps the pins on their plugs clean."

Donald