Question

Hi Tom, When I plug in 240v from house to campervan & switch on fridge, the RCB trips on supply to fridge, battery charger & water heater. I have removed the 2 fuses from the water heater. The circuit does not trip when the fridge is switched off. Your help would be greatly appreciated. Kind regards, Hugh

Answer

The 230 volt heating element is almost certainly the problem and will need replacing.