# How much light does a shop need?

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• posted on September 28, 2003, 4:03 am
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 applied soon.
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 painted.
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

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• posted on September 28, 2003, 4:35 am
The book I have says you want 50 foot candles measured 30" from the floor. That will be more on the order of 1.5 - 4 w/ft flourecent. I suppose if OSHA isn't inspecting your shop you can go with less.

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• posted on September 28, 2003, 8:43 am
Greg Fretwell responds:

What book, Greg?
Charlie Self
"Don't hit at all if it is honorably possible to avoid hitting; but never hit soft." Theodore Roosevelt

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• posted on September 29, 2003, 3:48 am

IBM Physical Planning Guide

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• posted on October 6, 2003, 11:32 pm
: The book I have says you want 50 foot candles measured 30" from the floor. That : will be more on the order of 1.5 - 4 w/ft flourecent. I suppose if OSHA isn't : inspecting your shop you can go with less.
I have eight 4-foot bulbs on the ceiling of my shop, which is about 260 sf. They're either 32 or 40 watt, and they seem about right -- lots of light, but not too bright (floor is a medium brown color). That's about 1 watt per sf (ceilings are 10 feet) (assuming 32 watts).

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• posted on October 7, 2003, 12:26 am

Flourescent lights have a problem with color accuracy. I don't like them in places where color is important, like kitchens (food color matters !) and anywhere I might be trying to match a color (we take color samples out of the store into the sunlight to check them).
So, my shop (about 600 sq.ft., 9' walls, vaulted ceiling, white walls) has 20 in-ceiling "cans" for light, about 1/3rd of which have halogen floods and the rest have 75W incandescent floods. For daytime work, it has three skylights, two medium windows, and three small ones.
It's enough.
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Dennis M. O'Connor snipped-for-privacy@primenet.com

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• posted on September 28, 2003, 11:16 am
Doug in Utah wrote:

I'll say. My set up has 20 four foot fixtures (40 tubes) at about 7'. My walls are white though I didn't fret over the additives making up the color (colour David) and my floor is green, OK, it's sea foam green. I don't have a finished ceiling. The shop is a wee bit over 600 sq. ft.
Conclusion, it's too dark. Don't get me wrong. It's more than adequate to get around, see everything and read by but I could stand for it to be a little brighter. Of course my eyes will also be celebrating a half century birthday in a couple/few years.
UA100

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• posted on September 28, 2003, 11:46 am
Unisaw A100 writes:

Yes. My VA shop has 1200 sf. The ceiling at 9' is white, with 16 two tube fluors, for a total of 32. The light is ample, and evenly spread: big difference is simply a semi-gloss white ceiling. Walls are unpainted OSB, floor is gray.
And I've had cataract surgery since I got to use the shop much, so it should be even closer to correct.
But that's not to say that close up work doesn't require task lighting. It does.
When I get back--anyone wanna buy a small house in WV?--I have 2 more two tube fixtures to place around, plus a couple four tubers. They may get set directly over the base cabinet area, with maybe one over the main workbench.
Charlie Self
"Don't hit at all if it is honorably possible to avoid hitting; but never hit soft." Theodore Roosevelt

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• posted on September 28, 2003, 1:51 pm
My shop has 600sq ft with only 4 such fixtures. . .I suspect I am dangerously under illuminated. . .<s> I have 2 3x5 and 2 4x3 windows tho. I am thinking tho that my tubes are 35w but I could be wrong. . .there is this old saying about old age and memory, but I forget how it goes. . .<s>
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SwampBug
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• posted on September 28, 2003, 5:41 pm
wrote:

My shop is only 252 sq feet, ten foot ceiling but I have 75 sq ft of windows. Three 30x48 windows are high on one wall, the other 3 are placed directly in front of the tool workstations I use most. I have a 5x5 window for my scroll saw and a beautiful view to boot!

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• posted on September 29, 2003, 3:17 am
so how many light fixtures do you have. . .<s>
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SwampBug
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• posted on September 29, 2003, 4:08 am
wrote:

4 four foot double fluorescents with daylight tubes. Two tri-light ceiling fans, and 6 lamps on the individual tools. I've tried to light the room so no shadows fall on my work. I'm also considering putting in 3 more 30x48 windows.<g>

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• posted on September 29, 2003, 2:11 pm
Goodness!, I guess I must be tragically under illuminated. . .<s>
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SwampBug
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• posted on September 29, 2003, 3:30 pm
wrote:

hehe. I'm planning for the future. I find as I get older more light keeps my fingers safe. If I could I would work outside. I love natural light, but dislike cold, wind, and mosquitoes. My girlfriend even hauls her sewing machine into my shop to do fine work, sawdust and all.

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• posted on September 28, 2003, 12:50 pm
<snip>

i can't stand the light or noise of fluorescent fixtures. i used ten 150W Halogen bulbs in my two car shop. light tan painted plywood walls. open ceiling, bare fixtures, no reflectors, new concrete floor. i call it my stadium lighting. i have it on three switches, 2 switches with 2 fixtures and one switch of 6 fixtures. i do use task lights as needed. yes, i'm creeping up on the half century mark too.
just my two cents, Myx

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• posted on September 28, 2003, 3:25 pm
Mixlepixle wrote:

Ahhh, but that only means you've bought the cheap ass models. I didn't spend entirely too much more (one, maybe two price jumps over *shop lights*) and mine have nary a humlette after 3 years.
'Sides, once you have machines running, the hum goes away.
UA100

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• posted on September 28, 2003, 3:57 pm

If you also up the price you pay on the lights themselves, you can get the full spectrum lights. Colour balance is closer to that of sunlight.
Mike

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• posted on September 28, 2003, 4:30 pm
Michael Daly wrote:

The good ones don't have the florescent flicker that drives some people nuts either.

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• posted on September 28, 2003, 4:37 pm
wrote:

Both Mr Bohn and Mr Daily made valid points, however, they still don't apply. I bought the best fixtures recommended to me buy a lighting consultant and the sunlight balanced tubes and installed them in my basement craft area. (Flytying, tackle craft, rod building, wife's sewing) This is a 20 x 25 additional basement space under an addition I put on 4 years ago. I can still hear the fixtures. My wife cannot. I still see the light as blue and don't like it. I guess i just dislike fluorescent light. as a significant downside, tube storage is a pain. Now i hang them between floor joists but I don't care for it. The halogen bulbs are stored in a small box in the dead space under my bandsaw cabinet.
Thanks for the suggestions anyway, Myx

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• posted on September 28, 2003, 5:01 pm
MyxlePixle wrote:

Maybe you're nuts and you don't know it.
UA100