Hi Rog
Sorry my mistake, 1 immersion heater with 2 thermostats, but only 1 thermostat has a cut out switch, and this obviously thinks the other thermostat is faulty and allowing the water to overheat, so the cut out comes into operation. This is no problem until connected to shore supply and using the hot water, then when no more hot water i need to access the imersion heater and reset the trip switch.
Ed Holmes