AWG needed for 68.5 amp 240 vac?

[Bill C]

Hello,

Can someone please tell me what AWG copper line is required to service a

68.5 amp 240vac tankless water heater? The manufacturer recommends an 80 amp breaker.

Thank you

Bill

[TURTLE]

there is all kinds of type wire to choose from as distance of run and as in conduit or not and you can run it in # 6 to a # 2 by just what type wire it is and the metal the wire is made out of.

So if run in Copper wire run # 2 and you can't go wrong. the wire can be smaller if you tell the conditions like length of run , type of wire you have to use , and in conduit or out.

TURTLE

[Doug Miller]

Anywhere between #6 and #2. Depends on the temperature ratings of the conductors, and how they're installed (cable, conduit, etc).

[RBM]

[Bill C]

Thanks everyone. I don't like my subpanel setup. It's a big mess to upgrade and a long run in an old house to try to pull new wire. I'll just replace this failing tank water heater with another tank water heater.

Regards Bill

[Stormin Mormon]

Also, copper versus aluminum makes a difference. I don't have a spec sheet, but alum takes a lower number. Which is a physically larger wire.

[zxcvbob]

He needs ampacity of 85A rather than 68.5 because it's a continuous resistive load. #3 Aluminum type SE cable will work if the breaker and terminals are rated for 90°C. Otherwise, he needs #4 copper rated for

75°C or better.

Best regards, Bob