Unit Breaker Size

[chino]

Heater Amps = 15.6Amps
Motor Amps = 1Amp
How am I going to factor this unit with the right fuse/breaker size? And what is this called then? (i.e. demand factor, _____ factor)

Thanks,
Chino

 

[charlie]

Re: Unit Breaker Size

You first.

It is customary for the person asking an exam type question to come up with the answer first and then others will jump in and help with your calculations. You will get all the help you need but we will not generally do the work for you. :roll:

 

[chino]

Re: Unit Breaker Size

I'm sorry about that, it was my first time to inquire something like this. But anyway what throws me off to double check my doubt is that the VAV unit has the heating element amperage of 15.6 and motor at 1A at 277V. With a total load of 16.6 with a 125%(? Factor) my calculation is telling me to fuse this at 25A with a #10 gauge Cu wire. Am I right? Now if I'm not, is it right for this unit to have a factory installed in-line fuse at 30A?

 

[petersonra]

Re: Unit Breaker Size

Originally posted by chino:
I'm sorry about that, it was my first time to inquire something like this. But anyway what throws me off to double check my doubt is that the VAV unit has the heating element amperage of 15.6 and motor at 1A at 277V. With a total load of 16.6 with a 125%(? Factor) my calculation is telling me to fuse this at 25A with a #10 gauge Cu wire. Am I right? Now if I'm not, is it right for this unit to have a factory installed in-line fuse at 30A?

There are somewhat different rules UL uses for supplemetal fusing of such devices then what the NEC calls for. You may also find wire sizes somewhat smaller inside UL listed assemblies as opposed to premises wiring for the same amperage.