lumins per foot

[thightower]

Since I didn't get a answer in my other thread figured I'd ask again. Anyone know the rule of thumb for lumins per foot for shop lighting? Looked for it in the forum, but couldn't find it.

 

[Steevo]

100 for causal use, 150 for working space, 200 for fine detail work.

 

[thightower]

Thanks

 

[Random Guy]

Just a side note, but it's spelled "lumens".

 

[mothgrey]

100 for causal use, 150 for working space, 200 for fine detail work.

So this is recommended per SQFT. So for a 1500 SQFT building at the working 150 you would need 225,000 lumens?
So if a T8 4ft bulb is 2700 lumens you would need 83 bulbs or roughly 42 fixtures?

Is that right?

 

[jvitez]

Correct mothgrey. That's lumens at the fixture. There will be light losses if it's enclosed, eventually by dust, and by diffusion before the light hits your desired light plane on whatever you are working.

 

[Steevo]

So this is recommended per SQFT. So for a 1500 SQFT building at the working 150 you would need 225,000 lumens?
So if a T8 4ft bulb is 2700 lumens you would need 83 bulbs or roughly 42 fixtures?

Is that right?

Correct.
I went closer to the 200 per sq/ft number by using 17 four-bulb 8' fixtures (68 tubes), in a 960 sq/ft area.

 

[Angelfire]

Read this to your hearts content:

http://www.sawmillcreek.org/content.php?146-Lighting-the-Small-Workshop-by-Jack-Lindsey&page=3

 

[DustynF]

Lithonia has a great tool to download that will help on placement and the amount of bulbs you will need. I am setting around 50 ft candles per sq foot. Granted my walls are white and ceiling is white as well which helps.

 

[Angelfire]

I planned my system for 100 lumens/SqFt. I have a few of the lights up but no where near the final number and it's already light in there. However, my eyes aren't what they used to be and aren't going to get any better so I plan to fully install the remainder after insulation, drywall, electrical, tile, etc... It'll be a while!

 

[Broadie]

In another thread someone mentioned 1 Watt per square foot was the rule. I come up with almost twice as many fixtures when I calculate with lumens vs. watts?

Also, how many T8 4 bulb fixtures can you put on 1 switch?

 

[mothgrey]

In another thread someone mentioned 1 Watt per square foot was the rule. I come up with almost twice as many fixtures when I calculate with lumens vs. watts?

Also, how many T8 4 bulb fixtures can you put on 1 switch?

Well that would be based off the Amp draw from the fixture. If it was 1 amp per fixture and I think you only want to run 80% of the curcuit then a 20 amp curcuit could run 16 fixtures but you also need to account for startup draw. So it would be less I think. You need to know the amp draw....

 

[bczygan]

The old thinking said brighter was better. But studies have shown that too much light can hurt your eyes. It's better to provide a certain level of general illumination and then provide task lighting at locations where tasks are performed. Direction and color of light are important. Providing light sources so shadows are eliminated or created, depending on the need, can make work easier.

 

[210Hardtop]

Mine is approximately 1.5 watts/Sq Ft.
I'm really happy with the light level.
14, 4 lamps fixtures @ 32 W.
Shop is 1200 sq ft

 

[Ray916MN]

The two factors that seem to be under considered are ceiling height and ceiling loss. Almost all the calculators do not have provisions for considering these factors and implicitly assume there is no loss.

Some tools mention assuming a 50% loss at the ceiling (assumption is a bare bulb fixture with no reflector).

When thinking about height, it is useful to realize that the amount of wall surface being lit increases proportionately with height and that the ratio of wall surface to floor surface is dimension dependent. A 400 sq. ft. 20x20x10 building has 80 sq. ft. of wall space, a 10x40x10 building has 100 sq. ft. of wall space. Counting only the floors and walls, in the first case you're lighting 480 sq. ft and in the second case 500 sq. ft. Double the wall height, assuming you're not lighting the ceiling and in the first case you have 560 sq. ft. being lit, while in the second case you have 600 sq. ft. being lit. The net is you have to keep in mind that you are not just lighting the floor, but you are also lighting the walls and ceiling to some degree.

 

[thightower]

The main reason I asked was for those short times in the shop. Dad installed 10 light sockets in which I have the flurecent 23w bulbs in them. He also installed 3 HID lights down the middle of the shop, they work well, but take several minutes to come on fully. I was wanting to replace the light sockets with some 4 foot, 2 bulb flurecents. Just to take away the shadows in the corners and sides of the shop. Thanks for all the info.