I recent purchased a heater that is rated 42.2 amps @ 240 volts. I was told by a licensed electrician that 8 awg would be fine for the heater. I have read some forums and now am questioning that also. I am wiring it in @ 220v So my questions are. Will it pull more amps @ 220v and if so how much? And will 8awg wire be good for the install?

#8 will likely be fine unless the distance is excessive.

Most services in the US is 120/240. 220 has gone by the wayside.

To answer your question though, the heater will draw less amps at 220 V.

#8 will likely be fine unless the distance is excessive.

Most services in the US is 120/240. 220 has gone by the wayside.

To answer your question though, the heater will draw less amps at 220 V.

Ty for your reply... So are you saying a 40 amp breaker will hold?

Guess that was my next question... olol will a 40 amp breaker hold or should I step up to a 50.. and If I go 50 will I have to drop to 6awg?

Usually when you step up in volts on a multi-volt unit... the amps drop. So I figured goind from 240 to 220 would pull a few more amps.

That's a disagree. Can't change it.

It's not correct to use a 50 A breaker and #8.

EDIT: #6 and 60 A breaker because on more than 3 hrs/day and breaker has to be rated > 125% of load, rounded up to nearest breaker size. Thanks, stan

WHOA guys!

First off forget the 220-240v thing. "220" is an old term that we just can't seem to shake. It's 230 or 240 volt. Commercial and industrial setting will also have 208v, but 99.999% of the time in a home it is 120/240v and nothing else.

NOW... this heater draws OVER 40 amps. You can completely rule out #8 NM cable. In fact, you can also rule out a 50A circuit. You cannot even use #8THHN in conduit as that is only rated for a 50A circuit. If an electrician told you #8 he needs to brush up on his code.

You need a minimum of #6 on a 60A breaker. Electric heat MUST be figured at 125%. 42.2x125%=52.75A minimum circuit. This get rounded up to a 60 since there is no 55A breaker.

If you are running NM cable you can run 6/2NM for this "straight 240v" circuit.

Oops. It's on more than 3 hrs/day. Stan's right.

Ty very much for your replys... you guys have given me more info tonight than Ive gotten anywhere in the last week. Stan you said a minimum on 60 amp and #6 awg wire. Would you see it safer with a 70 amp breaker? If so would 6awg still be good for the install. My main concern if overheating and fire of course. I want to be as safe as possible. Thanks again guys... GREAT HELP!!

Oops. It's on more than 3 hrs/day. Stan's right.


Has nothing to do with being on more than 3 hours per day.

Branch circuits for electric heat is always rated 125% of the load, period.

I saw this earlier, but had problems getting back online, glad that Stan picked up on this.

The electrician that said #8 was fine scares me.

Stan you said a minimum on 60 amp and #6 awg wire. Would you see it safer with a 70 amp breaker?
No, 60 is more than enough "cushion".

Thanks again guys great help!!