commercial garage load calc?

[journeyman0217]

hey guys, was trying to figure out my load calculation for a commercial garage. according to table 220.12 it says to use .5 va per sq ft for general lighting loads. the building is 50'x90' so I am coming in at 2250va. my question is, if I know my exact lighting load is 2760w (12 fixtures @ 230w ea.), do I add that to the general 2250va or do I just use the 2760w?

 

[Ingenieur]

You should use the higher/actual value
repair workshop or parking/storage?

does not seem like enough fc
a little over 1/2 W/sq ft

guidelines http://www.bristolite.com/interfaces/media/Footcandle Recommendations by Guth.pdf
50-75-100 fc

general rule of thumb avg clg ht 1 W/sq ft ~40 fc
you are 1/2 that

 

[Fitzdrew516]

You should use the higher/actual value
repair workshop or parking/storage?

does not seem like enough fc
a little over 1/2 W/sq ft

guidelines http://www.bristolite.com/interfaces/media/Footcandle Recommendations by Guth.pdf
50-75-100 fc

general rule of thumb avg clg ht 1 W/sq ft ~40 fc
you are 1/2 that

You can't use wattage per square foot as a way to determine light levels, especially with LED's now. If you use (12) of Cree's 240W CXB fixture in a 50x90 garage assuming lights are at 15 feet A.F.F. and deck is @ 18 feet - the average fc level is 53.2 with a max of 86.4 fc.

 

[Ingenieur]

You can't use wattage per square foot as a way to determine light levels, especially with LED's now. If you use (12) of Cree's 240W CXB fixture in a 50x90 garage assuming lights are at 15 feet A.F.F. and deck is @ 18 feet - the average fc level is 53.2 with a max of 86.4 fc.

obviously not with leds
run it with a 20x20 room 10 ft clg
med reflec
6 x 2 tube x 4' flour fixtures drop in

I'll try later after class

 

[Ingenieur]

CU 0.60
LL factor 0.90
ballast factor 0.90
lamp 2850 lumens
I get 0.96 w/sq ft
20x20 room
6 x 2 lamp x 32w fixtures
40 fc desired avg

no class!
spring break!

 

[Ingenieur]

Using the cree leds
rough numbers adjusting for 40 fc
(40/53) x (12 x 240) / (90 x 50) ~ 0.5 w/sq ft
Led basically twice as efficient

 

[topgone]

hey guys, was trying to figure out my load calculation for a commercial garage. according to table 220.12 it says to use .5 va per sq ft for general lighting loads. the building is 50'x90' so I am coming in at 2250va. my question is, if I know my exact lighting load is 2760w (12 fixtures @ 230w ea.), do I add that to the general 2250va or do I just use the 2760w?

Use the 2760W. 1/2VA per square foot is for garage lighting only. All other loads will have to be added to the lighting load so you'll get your service size.

 

[Sahib]

1/2VA per square foot is for garage lighting only. All other loads will have to be added to the lighting load so you'll get your service size.

In that case using 1/2W/sq.ft instead of actual load would also not matter.

 

[journeyman0217]

thanks guys for the response, the lighting company recommended the luminaire. it is a high bay lamp putting out 4400 lumens and 230w. that will fill the 50' x 70' space and have 34fc. the other 20' of the building will be office and bathroom which will require different lighting. the 50' x 70' section is for truck and equipment storage and maintenance work for a landscaper.