My caravan has been in indoor storage all winter and is now on a seasonal pitch. When I plugged in the electricity and turned on the fridge the power tripped the site box. A caravan repair guy said it was the fridge, which needed a new heating element. I have brought the fridge home to repair. However, on Monday I returned to the caravan and all was well with the electric. Heating worked all afternoon, boiled kettle, used microwave (one at a time so not to overload system). Only other thing on was the coolbox. Then at midnight the power tripped again. Nothing additional had been turned on, just heater and coolbox running. Even after resetting trip electric did not return. Any ideas where to start searching for the problem?