lighting load

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You don?t. That is, you don?t start there. You start in NEC Article 220, if you are doing calculations.

But I really don?t understand your question. Is this an existing circuit? Are you planning to install a new circuit? What type of facility are you talking about (dwelling unit, bank, church, hotel, office, etc.)?
 
Planning a new (temporary ) circuit in a correctional facility .Just looking for a simple formula to get in the ballpark for the load...
 
are the light incandescents or flourescents lights, r u talking about stringers of temp lights, those r incandescents. for incandescents u count up the wattage for each bulb roughly its 75watts a bulb, u r basically allowed 1400w per 120v circuit on a 15a breaker, if they r flourescents u go by amperage on the ballast which mostly r .25 to .50 amps a ballast.
 
A circuit does not have a "lighting load". Are you looking for the number of fixtures that may be put on a circuit? If so, that is entirely dependant on the type of fixtures that you are installing. If you are looking for a minimum lighting load for an area, go to articke 220 and look for the type of occupancy on which you are working? We need more information before giving you any kind of sensible answer.
 
I believe you said temporary lighting in a jail. I assume this is for a construction site since you used the word temporary. We usually figure 3 watts per square foot. Lets say you have 6,000 sq. ft., that would be 18,000 watts (6,000 X 3). Perhaps use #10 wire with 30 amp breakers. 30A X 120V X .8 (80%) = 2,880W. That would be 2,880 watts maximum per circuit. Now take 18,000 / 2,880 = 6.25. Rounding up, 6.25 would be a minimum of 7 circuits. Okay, now take 18,000 and divide by 7 and you get 2,571 watts per circuit. Using 100 watt incandescent bulbs, you take 2,571 and divide by 100 and you get 25.71 bulbs per circuit. That would be 25 or 26 bulbs per circuit or 180 bulbs all together. Also 18,000 / 100 = 180. If you are coming off 3-phase panel you can use #10/3 romex from panel to first light fixture and then branch off in 3 directions from there with #10/2 romex. Do that twice and you have 6 of your 7 circuits. Then just run one circuit by itself with #10/2. Of course this is all just hypothetical since we don't know exactly what your situation is.
 
adrian33773 said:
Perhaps use #10 wire with 30 amp breakers.
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Adrian, that is a violation, check 210.23(B) (2002 NEC)

Only fixed lighting outlets with heavy duty lamp holders may be supplied by a 30 amp circuit.


I am not trying to bust your chops, I agree with your post as long as you readjust your figures for 20 amp circuits.
 
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