I just moved into a house. I have a 50 amp max tankless water heater. The circuit breaker is 50 amps. The water heater is connected to a NEMA 10-50 power receptacle. There a switch to turn on and off the water heater from inside the house. I am going to replace the switch. I noticed that it is a double pole 30 amp switch.
I haven't tested the water heater yet and I am going to replace the switch, but I would like to know if this is a safe setup, since the switch's amperage is lower than the water heater's max.