We are installing 2 double pole 40 amp breakers for an electric tankless hot water heater, into our 200 amp panel. Is that going to use 80 amps or 160 amps?
2 Answers
Assuming you are in the USA, this will allow up to 80 amps @ 240 volts, out of the 200 amps available.
The draw will be less than 80 amps, code limits the breaker size to 60 amps with the current draw at a max of 48a NEC 424.22 so multiple breakers are used the wattage of the heater will provide the maximum demand that the heater will use.