You didn't mention it in the OP, but it seems this is a Fifth Wheel with 50-Amp (A) service. My clues were "fireplace" and "vacuum."
Everybody suspects that the problem is that 240-Volts AC Power (VAC) got applied to the 120VAC circuits within the RV. This is probably what happened, but the problem usually happens to 30A RV's, not the 50A ones. The 30A RV plug (which has three prongs) looks so heavy duty that people confuse it with plugs for things like clothes dryers which are 240VAC with three prongs.
50A RV's run on TWO 120VAC circuits, 50A each.
30A has Neutral, Safety Ground, and HOT (three prongs) for one 120VAC/30A circuit
50A has Neutral, Safety Ground, and TWO HOT (FOUR prongs) for TWO 120VAC/50A circuits
If the 50A is miswired, one or both of those 50A circuits could become 240VAC
Same problem (120VAC appliances get damaged). Just a little harder to visualize.
EDIT - RCMAN posted while I was writing and explained parts of what I said but better. Take a look at
This Wiring Thread particularly RoyB's excellent illustrations. Black is one 120VAC Hot leg and Red is the other. You can see Neutral in White and Neutral is ESSENTIAL to be just that, as the incoming 240VAC gets divided into TWO 120VC circuits within the RV. PLEASE NOTE that the GROUND is in fact wired, the diagrams just show a little green "tail" to simplify the illustration.
