Is it unsafe to use a 40amp breaker and 8 AWG wire with a 6000watt 240v (25 amp) water heater?

Question

The old water heater needed the 40amp breaker but the new one will only need a 30amp breaker as we are getting a slightly smaller one. Can I use the old wiring and old 40amp breaker or do I have to get a 30amp breaker. I would rather not spend the extra money on a new one.

Answer 1

If the 40 amp breaker is good,you should be able to use it,it just won't trip as fast as the smaller 30 amp breaker.

If the wire is rated for 240V and in good condition,it should be ok.

The amp rating on the circuit breaker means that it will trip if amperage draw exceeds 40 amps. This means that you should be able to connect a 15 amp 240V device to the same line as the heater without tripping the breaker. 40 amp minus 25 amp for the heater.

Circuit breakers are a safety device and if you don't plan to add on to the circuit,I'd recommend that you change to the lower amp breaker.

You can put the 40 amp back for later if you need it.

Answer 2

You should be OK. If you multiply the voltage by the amperage you get the max. load in watts. 40 x 240 = 9600 watts. SO your new water heater will certainly not overload the existing circuit.