[donf]

Why are most receptacle outlets rated at 1 amp when calculating loads?

"Pf" (Power Factor) Why do need to know that when planing the calculated load on some branch circuits?

[tkrussell]

Where is it are these values stated, I assume in the Code?

[donf]

Tk,

No, not the NEC. I came across these references and in an electrical, "How to". The section I was reading had to do with planning of branch circuits. The author said that if you set the ampere rate at 1 Amp, then you can apply a 120 VA to each receptacle outlet. Then you can figure out the number of receptacles you can put on the branch circuit.

What did not make sense to me was the ampere rating of 1. The given is that you have no idea what will actually be plugged in.

The Power Factor was brought up during a discussion of fluorescent ballasts. It was stated that in order to get the correct VA, when given the Watts, you have divide the Watts by the PF to get the VA.

FYI - This not related to the class on the NEC that starts tomorrow. So it is not a test or homework question.

[tkrussell]

Some "How to" books are not so good. In my opinion, I have no idea where they get some of the info. I suppose if you were to ask then they could come up with some sort of reasonable answer.

Code states that non-residential receptacles use 180 VA (1.5 Amps @ 120 Volts) when calculating load of a circuit. The 120 VA could be the authors method of being conservative.

Pf is lost energy, but increases the amperage of a circuit, feeder, service.

If you have the VA, why is the watts important? Yes, VA= P/PF, but you need to know the PF. A ballast label will list the line amps and the line voltage, say 2 amps at 120 volts, which is 240 VA. This is what is needed to do circuit and service calculations, not watts.

Either I need the nameplate amps or the VA, watts is irrelevant.

[donf]

Thanks for the clarifications.