Hi,
If you tripped a 30 amp breaker in the house, probably what happened is the 12.5 amp electric heater, refrigerator and perhaps the water heater where all on at once, and that might have caused it to go over 30 amps.
Even the battery charger (if it was low might have been drawing as much as 7 amps) and the electric heater along with something like the microwave or a hair dryer, it will exceed 30 amps.
I would try re-setting it, and then run the heater on low setting. THis will probably keep it below 30 amps.
If you are on a 20 amp circuit with the adapter from the RV, you might not be able to use any electric heaters, or make sure the refrigerator is on gas, the water heater is not on electric, and you should be OK on the heater if it stays on low output.
Also if you are at a friend's house, they might be running a TV or computer inside the house, also using part of the 15 or 20 amps that can trip a home circuit breaker, if you are plugged into the garage or other outside receptacle. And any Christmas lights might also be on the same breaker - they would have gone off at the same time as the RV lost power if so.
The best places to plug into while visiting friends are the washing machine receptacle, it is dedicated 20 amp PER NEC requirements. Or if they have a 4 wire 30 amp dryer, you can adapt that to feed your 50 amp RV with a home made adapter.
Fred.