[davidloi]

Hi, I want to hook up a 9.2kw stiebel eltron dhc 10-2 tankless water heater to a Square D QO electrical panel and it requires a 50A circuit breaker and 8-gauge electrical cable (3 conductors?), should I buy a 1-pole or 2-pole plug in circuit breaker? Why? What is the difference between a 1-pole and 2-pole even though both are 50A? Thank you!

[hkstroud]

You will need a double pole 50 amp breaker and 8-2 with ground cable. Granted that is three wires, two conductors and the ground wire, but the ground wire is not a conductor.
You need a double pole breaker because the heater requires 240 volts. You get 240 volts (in USA) by connecting to the two 120V lines coming into the breaker box.

You must use a double pole breaker, not two single pole breakers because the two 120V lines must be disconnected at the same time.

Note 8-2 w/ground cable is not the same as 8-3 cable.

[stanfortyman]

I have to say, even though I know this will be an unpopular opinion, if you do not know the difference between a 1-pole and a 2-pole breaker, and you are considering #8 cable for a 50A circuit, you will be best served hiring an electrician to do this job.

[ma0641]

Amen.

[hfcarson]

Amen x2

[davidloi]

Thanks HKSTROUD for confirming for me which breaker and wire to buy and everyone else for your input. I do intend to hire a licensed electrician to hook everything up so it doesn't go poof! Amen (x2) indeed if I don't *LOL*

[hkstroud]

Let electrician purchase cable and breaker. Specifications of water heater calls for #8 cable but there are different types of cable. If distance is very much it may be best to use aluminum cable.