Unit heater

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Standard KW

Standard KW

Just out of curiosity. Where do these numbers come from? Many heaters are 4K 5K etc. creating problems with sizing the conductors. For example, if the heater were 3.8 kw that would make life easier for everyone?
 
Mgraw said:
Most 5kw heaters are not 5kw. Usually 4.8kw. Make and model of the OP's heater would help.
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Seems to be common for heat strips installed in an air handler to be called 5kw nominal though actual rating is 4.8kW , but a 5000 watt "unit heater" is usually 5000 watts.
 
I am pretty much convinced you would never have any problem using a 6000 watt heater on 10 AWG on a 30 amp breaker, but do agree if you want to comply with NEC that this should be on 8 AWG on a 35 amp breaker. The deal changer may be that the instructions state 10 AWG and 30 amps - would like to know why they state that though, unless actual watts is only 5750 or something like that.
 
LarryFine said:
Clamp-on ammeter, anyone?
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Well if actual rating is 6000 watts @ 240 volts, then if your input voltage were only 230 (still within 10% of nominal 240) you would measure about 24 amps.

But if your actual input were 250 (also within 10% of nominal) you would measure about 26 amps.

NEC wants us to use nominal ratings for such calculations.
 
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