I guess there are standards which say how much light a shop should have. I don
t know what they are. However, I just finished putting up my lights and I now
have some numbers which could be used as a point of real world reference.
I have built a large shop with ten-foot ceilings. Since I had about thirty
fixtures (dual, 40 watt shop lights) I used them. (Hindsight would suggest that
running continuous dual eight-footers would have been a better choice.) They
are hanging about seven inches from the ceiling. The drywall walls and ceiling
are painted white. (Actually, white base with 5/96 of an ounce of magenta per
five gallons just to make it a bit warmer than pure white. If I had it to do
over I would go with 5/48 of an ounce of magenta.)
I have a smooth, bare, gray concrete floor which will have a light almond epoxy
I installed 27 fixtures in an area just under 1400 sq. ft. When I turn them on
I find it is almost too bright, and will be even more so when the floor is
The numbers are:
27 x 2 = 54 four-foot, 40-watt fluorescent bulbs.
1387 / 54 = ~one 40 watt bulb per 25 sq. ft. or 1.6 watts per sq. ft.
I would now say that 1.5 watts per sq. ft. is more than enough light for my
type of building. Probably 1 watt per sq. ft. would be adequate. YMMV.
-Doug in Utah