On a recent week away, on the sixth night we started to hear a buzzing noise coming from the fusebox and trip switches. After 10 minutes of isolating different fuses and switches, the buzzing stopped if we switched off the water heater. I left it off overnight and when i switched it on the morning after the buzzing had stopped. We are new to caravanning and unsure if this is a major problem or not, caravan is an 8 month old bailey ranger.