I would post your problem in the electrical posting: Electrical, Charging Systems & Solar - Forest River Forums
Do you have a multimeter, it sounds like you have a short and you should start looking at the outlets the heaters were plugged into. Could the heaters have been plugged into a GFI circuit that needs to be reset and/or went bad.
I do find it weird that 2 outlets on 2 separate circuits would have issues at the same time. Could you have had some kind of electrical surge from outside, do you have an EMS system to protect you from shore power issues.
Sorry more questions than answers, I would start at wall outlets looking for a short