Lighting the Small Workshop - by Jack Lindsey

[Jery Madigan]

I just finished setting up lighting for my basement. Jack is right that the "industrial" type lights are the most effective with unfinished ceilings. I bought several fixture types and lamp types and just tried them out. Ended up with the $35 diamond plate reflector lights from the borg and natural light (5000K) bulbs. The 5000K bulbs appear to give you more light per watt and the appearance is good for me. I did hand-bend the reflectors to broaden the light dispersion.

The nice thing about this kind of light is that you install switched outlets in the ceiling rather than a regular box and you can easily move the light around or even add another light after the fact to adjust to your shop arrangement.

[Steve Strobel]

Thanks Ken! Perfect timing. I'm getting ready to build a 24X30 shop and this answered all my lighting questions. Very informative and easy to understand. Thanks for not getting too technical. Steve

[Jason Roehl]

Ok, I've read the article, and it sounds like some great info. However, I could not help but comment on one small, inconsistent aspect of the article. The title speaks of lighting a SMALL shop, yet the example for the calculations is for that of a 1500 s.f. shop--roughly 4 times the usable space in a typical 2-car garage. I'm guessing here, but I'd say probably less than 1% of the folks here at SMC have a shop approaching 1500 s.f. or larger.

[Jack Lindsey]

Ok, I've read the article, and it sounds like some great info. However, I could not help but comment on one small, inconsistent aspect of the article. The title speaks of lighting a SMALL shop, yet the example for the calculations is for that of a 1500 s.f. shop--roughly 4 times the usable space in a typical 2-car garage. I'm guessing here, but I'd say probably less than 1% of the folks here at SMC have a shop approaching 1500 s.f. or larger.

Size is relative, Jason, and from a lighting perspective I consider a hobby type shop under a couple of thousand square feet to be small in terms of design complexity. The method I described is an approximation since it uses averages and will usually be within 10% or so of more detailed calculations based on greatly expanded design parameters. This is close enough to be useful, and more robust calculations aren't worth the time required since the final design willl probably be the same with either method. I understand your point about shop size. I started with half of a 2 car garage with machines parked against the walls when not in use. After many years I graduated to a dedicated 400 square foot building, and finally built a 1500 square foot building that I currently use. I used the simplified method to light all of them, and then did a detailed calculation to verify the estimate. In all cases the final design was the same.

[Jon Agnew]

Jack,

I sincerely appreciate the time and effort that went in to writing this article. As a Director of Photography, I know how difficult it can be to explain color temerature, footcandles, etc in a way that makes sense to the layperson. Not only is your article clear and concise, but highly informative. Despite the fact that I work with lighting every day and consider myself well versed on such matters, I learned quite a bit from you today. I will apply this, not only to my workshop, but to my daily work as well. Thanks again.

[Jack Lindsey]

Thanks, Jon, it's good to hear that the article was helpful.

[Mike OMelia]

My double garage is pretty standard. About 25x35 (875 sqf). I'm over 25, and my cieling is about 12 ft high. Finished. The calculator says 16 four bulb fixtures. Wow! Thats a lot (it seems). Yes, my current run of the mill 2 lamp fixtures (two of them) are inadequate. But it would never have crossed my mind to use 16. One other question is power requirements. How many of these fixtures can exist on a 15 or 20 amp circuit?

[Jack Lindsey]

My double garage is pretty standard. About 25x35 (875 sqf). I'm over 25, and my cieling is about 12 ft high. Finished. The calculator says 16 four bulb fixtures. Wow! Thats a lot (it seems). Yes, my current run of the mill 2 lamp fixtures (two of them) are inadequate. But it would never have crossed my mind to use 16. One other question is power requirements. How many of these fixtures can exist on a 15 or 20 amp circuit?

Sixteen fixtures sounds about right, Mike. Assuming you plan to use 8' fixtures I'd mount them in 4 rows of 4 fixtures per row, spaced about 6 1/2 feet apart, starting about 2 1/2 feet from the wall. The number of fixtures per circuit will depend on the current draw per fixture which unfortunately varies somewhat between ballasts. A lighting circuit can be loaded to 80% per the NEC so a 20 amp circuit can handle a max of 16 amps and a 15 amp circuit is good for 12. Standard engineering practice is to use a somewhat lighter loading, say in the 12 to 14 range. Four lamp 4' T8 ballasts can be expected to draw anywhere from about 3/4 of an amp to over 1.05 amps each so I'd plan on 2 circuits. That gives you the option of adding a few fixtures later if needed due to changing lighting requirements.

[Mike OMelia]

Jack, I really appreciate all the effort. It has really helped me figure out a path forward. I purchased some Metalux strip fixtures. 8 ft long. I may have erred here and want to find out before I go any further. The fixtures are HO or "High Output". They require high output bulbs that have a rectangular contact on the ends. Are these lights being phased out? No need in stalling them only to find I won't be able to get lights for them.

Mike

[Mike OMelia]

I punted, took them back and bought T8, 8 foot tandem fixtures, electronic ballasts. Four 4ft, 32 watt bulbs. Very nice. I don't get it, but the July 2012 phase out of many T12 bulbs is all over the Internet. But nobody at Lowes is aware of it. So they say.

[Mike OMelia]

I've gone back and studied Jack's calculator. Entered precise room measurements and the lumen ratings for the bulbs. I know, I estimated room size from memory and had it wrong. Never the less, the one variable that is totally subjective is the 50 or 100 factor based on age. I have one fixture up, and it's bright! If I add 3 more, I'm right in the ballpark using the 50 factor. I can't begin to believe I'd need much more than that. (room is 24x20, lumens = 2800, and I use a little over half that space since my wife parks her car in the garage.)

So, what's the lesson? Use the calculator to get an estimate started. Put up one fixture and judge for yourself whether u should go with 50 or 100. Regardless, it's a good indicator of what u will need within a factor of two.

Mike

[Jack Lindsey]

I've gone back and studied Jack's calculator. Entered precise room measurements and the lumen ratings for the bulbs. I know, I estimated room size from memory and had it wrong. Never the less, the one variable that is totally subjective is the 50 or 100 factor based on age. I have one fixture up, and it's bright! If I add 3 more, I'm right in the ballpark using the 50 factor. I can't begin to believe I'd need much more than that. (room is 24x20, lumens = 2800, and I use a little over half that space since my wife parks her car in the garage.)

So, what's the lesson? Use the calculator to get an estimate started. Put up one fixture and judge for yourself whether u should go with 50 or 100. Regardless, it's a good indicator of what u will need within a factor of two.

Mike

Sorry about the delay in getting back, Mike, I didn’t seeyour post when I checked the forum yesterday.
If you are referencing T12 HO’s then yes, they have beenbanned. This is well known in theprofessional lighting community so I’m surprised they weren’t aware of it.
As far as the 50 fc vs 100 fc issue is concerned it is aguideline, not a hard and fast rule. It’sbased on several factors, the most important being the types of visual tasks wehave in our shops, and the age of the worker. Most ofus perform a wide variety of visual tasks in our shops ranging from easy tomoderately difficult so age is the deciding factor. As we age our eyes begin to deteriorate andwe compensate for it with more light. That’s why we recommend two different levels. The breaking point isn’t absolute sincechanges in vision very between individuals, but most of us tend to follow thesame pattern. If you’re satisfied with less light or thinkyou want more that’s your option. Thearticle is based on averages, though, and most people seem to be satisfied ifthey follow the recommendations.
As a side note when I was teaching we had a demonstrationset up that allowed the students to use a dimming control to vary the lightinglevels for different seeing tasks to see what they liked. The vast majority preferred levels 2 to 4times the recommended levels. A few,very few, preferred lower levels.
The bottom line is that you need to determine what you wantin your shop. The guidelines I haveprovided will satisfy most people but not everyone. The alternative is to put up a few fixturesand see if you like it. If not, add more. Or you could hire a professional lightingdesigner.

[Mike OMelia]

Turns out its plenty of light. I added one more fixture based on 50 FC. I installed pull switches on several of them so I can turn some off when I don't need the whole area lit. Thanks for all if your help Jack!

Mike

[Jack Lindsey]

Turns out its plenty of light. I added one more fixture based on 50 FC. I installed pull switches on several of them so I can turn some off when I don't need the whole area lit. Thanks for all if your help Jack!

Mike

You're welcome, Mike. Glad you're satisfied with the system.

[Steve Strobel]

Jack, I need some advice to make a final decision on lighting. Shop being built is 24 by 30 with 9' ceiling. I would like to run the lighting the 24' distance so I'd use 2-8' and 1-4' fixture per row. I'm 50 so vision is far from perfect. Based on your info I should use 52- 4' lamps. I only want to wire this once so do you think I should run 5 rows of lights(50 lamps) or will 4 rows (40 lamps) really be enough? thanks Steve