Lighting demand factor of 125%

[MTG]

I'm having a debate with a colleague about the need to multiply the actual lighting load of a circuit by 125% when calculating the demand kVA of a panel. For example, if there are (10) 293W LED fixture on a circuit, the actual load of that circuit is 2,930VA (assume pf=1). My friend is saying that total needs to be multiplied by a load factor of 1.25 for lighting being a continuous load when calculating the load on the panel. My understanding is the 125% factor is only for determining the overcurrent protection and branch wiring size of THAT circuit, but the actual connected load (demand factor =1) is what is used to determine the load on the panel.

So who is correct? is the panel load = 2,930VA or =3,663VA?

 

[david luchini]

Technically the load would be 2930VA, as the 125% is not a demand factor.

However, the 125% factor for continuous load applies to the feeder as well as the branch circuits, so most people apply it when calculating load.

 

[MTG]

Technically the load would be 2930VA, as the 125% is not a demand factor.

However, the 125% factor for continuous load applies to the feeder as well as the branch circuits, so most people apply it when calculating load.

Thanks for the quick reply. In our situation, we are working from a existing 400A panel so the feeder is already in place. The question is if we are overloading the panel. If the loads are added with a demand factor of 1 (or 2930VA for one circuit in my example), we are below 400A on the panel. But if we use the 125% factor, we go over. Want to make sure we are being code compliant.

 

[charlie b]

I am having difficulty believing that the panel is that close to being overloaded. The extra 25% of 2,930 VA amounts to only 733 watts. That equates to about 2 amps on a 208V system and less than 1 amp on a 480V system. Are you really saying that the load on the 400 amp panel, not including the 125% factor, is as high as 398 or 399 amps?

With regard to the debate, I side with your colleague.

 

[MTG]

I am having difficulty believing that the panel is that close to being overloaded. The extra 25% of 2,930 VA amounts to only 733 watts. That equates to about 2 amps on a 208V system and less than 1 amp on a 480V system. Are you really saying that the load on the 400 amp panel, not including the 125% factor, is as high as 398 or 399 amps?

With regard to the debate, I side with your colleague.

There area actually 4 lighting panels powering about 800 hi bay fixtures in a warehouse. I was only using the one circuit as an example. These four panels (none of which are overloaded) are fed from a main distribution panel (600A) that also feeds an office power panel. Together, the lighting panels and office panels, using the 125% load factor for lighting, equal about 580 amps. If we didn't factor the lighting loads, the total load on the panel drops to just over 500A.

 

[charlie b]

As long as you account for all continuous loads (e.g., lights, largest motor, certain types of water heaters and space heaters, etc.) at 125%, and all non-continuous loads at 100%, you can take the load on the 600 amp panel all the way to 600 amps. So you have a small amount of spare capacity at present. Are you planning to add new load?