ECN Forum Forums General Topics of the Trade General Discussion Area Lighting Load

I've got a question on my continuing education test that I can't seem to come up with any of the answers they have to choose from. They're asking for the lighting load on a particular circuit in one of the panels. I go to the circuit directory and it gives me the room numbers. All the rooms have florescent fixtures. I count up the wattage from the lighting fixture schedule, and nothing matches. I then find out in the code that you're not suppose to count the wattage of the lamps to come up with the load, but you're to take the ampere ratings of the lights. I take it that this is the rating on the ballast? Problem is in this test it does not specify the amperage of the ballast. If I just take 20 amp circuit X 120 volts that doesn't come up either. Any suggesions here or is it possible there is not a right answer, and this is just a "trick" question? I'm sure I'm missing something somewhere. Thanks for your input. Steve..

Hmmm I thought lights were considered a continuous load...hint hint nudge nudge.

ITO, I wasn't very good in algebra

I found my mistake. I was missing a hall way that was included in my question. I talked to the one who made up the test and it seems that my understanding of 220-4b ( 99 code) is wrong or his is wrong. The correct answer for this questions was determined by adding total wattage of the lamps.

The question states:
What is the load on circuit 5 in panel LP-1? You then have to go to LP-1 to see what is on the circuit, which is flourescent lighting. Then go to the different fixture schedule to see what the bulb wattage in each of the fixtures is. Is this question and answer according to the code??


( 1999 code )
220-4b: For circuits supplying lighting units that have ballasts, transformers, or autotransformers, the computed load shall be based on the total ampere ratings of such units and not on the total watts of the lamps.

I think in this situation you have to give an answer based on the available information.