1500 watt heater. Enough?
I'm thinking of installing a 1500 watt, 120 volt, electric, wall mount heater in my 30 foot, 30 amp, class A. I know this thing isn't going to keep us warm when it's 20 degrees out but do you think it...
Forum Discussion
Chris Bryant wrote:afidel wrote:Chris Bryant wrote:
Fwiw, if you are hard wiring it, you can go up to 1800 watts on that 20 amp circuit.
Actually, I believe you can go even higher, like 1920 watts.
1800W is correct for a heater as it falls under continuous load so the circuit needs to be derated by 20%.
I thought 1920 was 20% down- 20 amps times 120 volts equals 2400 watts, less 480 watts (20% of 2400) equals 1920 watts.
Or is there an additional derating due to constant load? My NEC is still packed :)
Interestingly, in Canada we can run wire on fixed space heaters at 100% of it's rating while breakers must be derated to 80%. Heaters are considered non-continuous loads in buildings. Nothing burns up here, including our house which is part electric heat. AFAIK, the NEC still considers heaters to be continuous and requires derating of wire and breakers by 80% for fixed space heating. Fixed heaters in an RV are going to be a different thing because they won't cycle on/off like in a building (which will have good insulation and properly sized heaters) and I would def. not exceed 1440 watts on 15 amp wire and breaker or 1920 watts on 20 amp wire and breaker. Plug-in portable heaters are a different matter and can be rated at 1500 watts and have 16 ga. cord wire and be plugged into a 15 amp recept.
