Qty. 20A Ckts. Based On Watts

[mstrlucky74]

I'd like to determine how many 120v single phase 20a circuits I would need for the attached and would like to make sure I'm calculating correctly.


Total connected load is 3431 Watts. Don't I need to divide the watts by the result of the power factor x voltage? How do I determine power factor? Thanks.

 

[ptonsparky]

You would need to see the fixture specs to find the power factor.

For 3431 watts, they would get three circuits from me, maybe.

Add: Two if if I wanted to be low bid.

 

[mstrlucky74]

You would need to see the fixture specs to find the power factor.

For 3431 watts, they would get three circuits from me, maybe.

Add: Two if if I wanted to be low bid.

What PF are you assuming?

 

[Unbridled]

What PF are you assuming?

Continuous or non- continuous loads?

 

[GoldDigger]

Continuous or non- continuous loads?

Lighting is usually continuous (more than 3 hours at full power).
Except maybe in lights out datacenters and infrequently visited warehouse aisles.

 

[ptonsparky]

What PF are you assuming?

I didn't. 3431/120=28.5. 28.5/2 = 14.25 amps which is well within the capabilities of a 20 branch circuit for lighting, even for continuous duty.

 

[kwired]

Can you find specs on the luminaires?

Even if they don't tell you PF, you probably can find line amps pretty easily, then multiply by voltage to get VA.

Some LED's and electronic fluorescent ballasts have a pretty low power factor and draw more current then you would expect just looking at rated watts.

 

[mstrlucky74]

Continuous or non- continuous loads?

Continuous