AC dead short?

[John Ely]

I have just developed a dead short in two circuits of my AC system.
The front receptacles and the vacuum cleaner circuits appear to be
dead shorted. If they are on, the park circuit breaker (30 amps)
trips. If they are off, I get normal service from the park. The
thing these two circuits have in common is the AC meters on the
dinette control panel. The front receptacles circuit provides power
to one of the dinette AC meters while the vacuum cleaner circuit
provides power to the other. I have removed all loads from both of
these circuits with no change. I've pulled the cover from the breaker
box and these breakers have only one 12ga. wire going to them, so the
meters must be wired in downstream somewhere, but I have no idea where
or even where to look. As a possibly related matter, about two weeks
ago, after a lightning storm near Montreal, I noted that the polarity
indicators in my service box (the place where shore power is
connected) are no longer working. As there are also polarity
indicators on the dinette panel, there is a possible likage here.
However, there was a two + week span of normality between the loss of
polarity lights in the service box and the short circuits in the AC
panel. No incident occurred prior to the AC loss; it worked fine in
one park, we took a long (15 hour ferry ride) with the DC systems shut
down, and had the shorts as soon as I plugged in at the next park.
If anyone has any ideas as to what this might be, I'd be glad to hear
them.
John Ely, 86PT40, Rapid City, SD On the road in Clarke's Beach,
Newfoundland