What amperage breaker do I need

[Tugmaster]

After alot of research I finally decided on getting one of these to heat my garage.http://www.air-n-water.com/product/g73.html It's a 20x20 attached garage with r-13 in the walls and r-19 in the overhead.
The specs and the owners manual don't state what size breaker I should use.
It's 5kw. I would assume 30 amps would be right but I don't want it to big.
Any ideas??
Thanks, Todd

 

[Milton Shaw]

I would wire with 10 gauge and 30 amp breaker. The listing says it's got a single pole thermostat, which means that one side of the circuit is always going to be hot. That means that if the heating element shorts out, the thermostat would not cut power off to the unit. I would suggest using a disconnect close to the heater to make sure you can isolate the heater from the power circuit. Appliances such as stoves do this and if the calrod shorts out, even turned off the calrod willarc like a welding rod until the whole element is consumed. Only fix is unplugging or cutting of the breaker when they short. Even a fire extinguisher will not put out that arc until it's all burned up.

 

[Captain Sparky]

That is surprising they don't give the total amps, but from my calculations I believe you are correct with a 30 amp breaker.

 

[Tugmaster]

I would wire with 10 gauge and 30 amp breaker. The listing says it's got a single pole thermostat, which means that one side of the circuit is always going to be hot. That means that if the heating element shorts out, the thermostat would not cut power off to the unit. I would suggest using a disconnect close to the heater to make sure you can isolate the heater from the power circuit. Appliances such as stoves do this and if the calrod shorts out, even turned off the calrod willarc like a welding rod until the whole element is consumed. Only fix is unplugging or cutting of the breaker when they short. Even a fire extinguisher will not put out that arc until it's all burned up.

I have a sub-panel in my garage right by where I plan on mounting my heater. I will be able to secure it at the breaker if need be. Todd

 

[Gary S]

5000w divided by 240v = 20.83 amps. Add a bit for the fan, and you are still well under the 30 amp breaker rating.

 

[jvitez]

watts/volts= amps. NEC/CEC rules state continuous loads (that will be on for 3 hours or more at a time) need to be wired and therefore breaker-ed (is that a real verb?) at 25% higher than standard capacity, ie multiply x 1.25. So:

5000/240=20.8 amps. 20.8 x 1.25= 26 amps. Now round up to the nearest usual size of breaker.

10 gauge wire can have a max breaker size of 30 amps. Therefore install 10/2 NM wire protected by a 30 amp breaker.