Commercial lighting loads

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ryan_618

ryan_618

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Salt Lake City, Utah
I did a plan review some time ago where the engineer had specified 2.3VA per square foot for lighting in a store tyoe occupancy. I wrote on my plan review that he needed to calculate the load at 3VA per sqaure foot, in accordance with table 220.3. He replied by stating the 2.3 was adaquete.

Before I talk with him tommorrow, I want to be 100% certain that I am correct on this. There are no demand factors that can applied to the lighting load in a store, correct? Or am I losing my mind?

I want to be certain of this, as the building in question is a 95,000 square foot store, and the difference on the service/feeder load would be about 80 amps. Thanks in advance.
 
Re: Commercial lighting loads

Hi Ryan,

As far as I can tell and from past experiences, you are correct.

HandBook:
General lighting loads determined by 220.3(A) are in fact minimum lighting loads, and there are no exceptions to these requirements.
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Also check Annex D. Example D3 Store Building
 
Re: Commercial lighting loads

This is just a guess, the engineer put the wrong number in by mistake. Example yes 3va per square foot was figured correctly by you and the electrician will have to do it that way, the engineer probably figured lumens per square foot then into watts per square foot and came up to a rounded off number of 2.3va. So if that is the case be kind to him and show him the way to figure from the code and he will save a lot of time figuring the load. Again this is just a guess.
 
Re: Commercial lighting loads

If your engineer designed the lighting layout for the place he may have been giving you the actual lighting connected load instead of the std 3va/ft^2 for demand calculations. When he said 2.3 was adequate, he may have thought you wanted him to add more lights?

Just a guess....
 
Re: Commercial lighting loads

Yes, he was giving me the connected load for the lights. I think there are a lot of misunderstandings about this, since the energy codes will not allow you to use that much power for lighting. A freind of mine named Noel Williams submitted a change to 220.3 to address this, but the response from the CMP was that the NEC is more concerned about the capacity of the system for future expansion. This seems to go against the scope of the code discussed in 90.1(B).

The ROC is #2-164
 
Re: Commercial lighting loads

And don't let him forget to add for any track lights, show windows, and the sign outlet required by 600.


Steve
 
Re: Commercial lighting loads

Originally posted by ryan_618:. . . the engineer had specified 2.3VA per square foot for lighting . . .
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I suggest taking an extra moment during the conversation with the engineer to agree of your respective use of terms. For example, in the sentence quoted above, what do you mean by ?specified?? As william and sceepe have indicated, the 2.3 might be a design choice that the engineer made. That would be acceptable. However, you are quite correct in asserting that the load calculations for the service and feeders must use the 3 VA/ft2, even if the initial installation uses less lighting.

In Washington State, we have an energy code that limits the VA/ft2 that certain types of buildings can use for lighting. We also have an exception to the NEC, as published in the WA Admin Code, that says that a load calculation may use the lower values of the energy code, in place of the higher values given in the NEC.
 
Re: Commercial lighting loads

Ryan, I remember Noel Williams (if this is the same person). He used to write electrical articles for Electrical Construction & Maintenance. Whatever happened to Noel?
 
Re: Commercial lighting loads

Hi Jerry. Noel lives out here in Utah, and as far as I know he is doing quite well. I don't want to say too much, in case I say something wrong, but I notice that all of his code proposals claim that he is with "Noel Williams Consulting". He teaches classes for our IAEI chapter on occassion, and what a rare pleasure it is to attend...the guy can take any curve ball you throw at him and knock it out of the park, ya know? It has been nice serving on the board of directors with him.
 
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