Lighting the Small Workshop - by Jack Lindsey

[Jack Lindsey]

Good questions, Steve. If your walls and ceiling are a light color, you have typical middle aged eyes with no severe uncorrected visual problems, and are doing common woodworking things like building furniture, cabinets, and some carving then 50 lamps should be fine. As far as the orientation of the rows goes there is no hard and fast rule so using 10 rows of two 8' 4 lamp fixtures and one 2 lamp 4' fixture per row running along the 24' dimension should be fine.

This is based on 32 watt T-8 lamps and following the general recommendations in the article. Let me know if the parameters are different and I'll modify the recommendation if necessary.

[Steve Strobel]

Good questions, Steve. If your walls and ceiling are a light color, you have typical middle aged eyes with no severe uncorrected visual problems, and are doing common woodworking things like building furniture, cabinets, and some carving then 50 lamps should be fine. As far as the orientation of the rows goes there is no hard and fast rule so using 10 rows of two 8' 4 lamp fixtures and one 2 lamp 4' fixture per row running along the 24' dimension should be fine.

This is based on 32 watt T-8 lamps and following the general recommendations in the article. Let me know if the parameters are different and I'll modify the recommendation if necessary.

I'm reading into what you said then, that 40 would be too few? Thanks again.

[Jack Lindsey]

The recommendation for 100 fc is based on typical middle aged eyes performing visual tasks typically encountered in woodworking shops. Forty fixtures could be expected to provide about 80 footcandles, on average. Will this be adequate for you? No way of telling unless you try it. Some people will be satisfied, others won't, so it's your call. When writing an article like this I had to consider the middle of the range for a large population of readers so most people would find the lighting adequate if they follow the guidelines.

When designing a lighting system we consider the fact that the light output decreases over time as the lamps deteriorate and dirt deposits on fixture surfaces so we design the system to provide more light than needed when new and clean. The loss can easily exceed 30% and is recoverable by relamping and cleaning the fixture surfaces. If cost is an issue and you want to try 40 fixtures you could maintain a higher lighting level with more frequent relamping and washing.

[Ken Fitzgerald]

Steve...My shop is 30'x24' with 10' ceilings. I used Jack's original article to design my lighting.

I placed 4 rows of 8' T-8 , 4 bulb fixtures. There are 3 rows of 3, 8' fixtures and 1 row of 2, 8' fixtures for a total of 44 bulbs. I eliminated 1, 8' fixture because it would been too close to my hanging gas furnace and I was sure that would be a problem in the fall, winter and early spring.

Each row has its own switch. So I turn on only what I need and yet, I can light the entire shop when I desire.

Everybody who has come into the shop has commented positively about the lighting and it works well with my 60 year old eyes.

[Bill W Jenkins]

Sorry, having issues copying and pasting from a Word Doc. The Word Doc is fine but it scrambles a bit when I paste it here.

[Bill W Jenkins]

I recently came across a warning from a kind person that wanted all to know about the strobe effect that fluorescent lighting can cause. I apologize if it was already mentioned.

The strobe effect can make your saw blades look as if they are standing still and he pointed out that this can cause a dangerous situation in the shop.

[Jack Lindsey]

I recently came across a warning from a kind person that wanted all to know about the strobe effect that fluorescent lighting can cause. I apologize if it was already mentioned.

The strobe effect can make your saw blades look as if they are standing still and he pointed out that this can cause a dangerous situation in the shop.

Strobe is seldom a problem with fluorescent lighting due to the decay time of the luminescence of the phosphors, as illustrated in figure 3 of the article. Some people may notice a minor strobe effect, especially with peripheral vision, but it isn't enough to make a spinning saw blade appear stationary. In fact, for a blade to appear to not move the blade would have to be spinning at some exact multiple of 60 Hz, which is seldom the case with an induction motor. Strobe can be a problem with high pressure sodium or clear (not phosphor coated) metal halide lamps unless they are installed on a 3 phase power distribution system with adjacent lamps staggered between phases.

[Bill W Jenkins]

Thanks for the extremely detailed response. The man who wanted to point this out had an accident. I seem to remember that he mentioned something about phase of power being part of the set up in his unfortuante situation. I may change my mind and use florescsnt lights but I will check for the strobe effect just to be safe. I can't remember but he may have been using a super quite hobby type table saw that also contributed. The photo of his finger kind of stuck with me.

[Ken Fitzgerald]

Bill,

While strobing effect is possible in theory, I use flourescent lighting. I do use 2 incandescent lamps over electronic variable speed lathe but only because both of the have the ability for adjusting their physical position. Some of the turnings require the light to be in some very different positions. I have never experienced any strobing effect with my shop tools.

[Bill W Jenkins]

Thanks! I now plan on using flourescent lighting for my small work area.

I can't remember for sure where I read about the strobe effect but I think I was on a site for building small street organs and it is very possible the man lived in Europe.

Bill

[Mike OMelia]

Whatever u choose, the ability to switch some off makes sense. I used Jack's formula, then integrated pull switches on some of the units (not unlike Ken's approach). What one might miss in all of this is that the proper number of bulbs eliminates shadows! This is an incredible feature. Parallax and all of that becomes a non-issue. Good luck!

Mike

[Ken Fitzgerald]

Mike,

I couldn't agree more! It's one of those situations a person has to experience for themself to fully appreciate. But when the lighting is properly designed and executed, it is a wonderful thing in which to work!

[Steve Strobel]

Steve...My shop is 30'x24' with 10' ceilings. I used Jack's original article to design my lighting.

I placed 4 rows of 8' T-8 , 4 bulb fixtures. There are 3 rows of 3, 8' fixtures and 1 row of 2, 8' fixtures for a total of 44 bulbs. I eliminated 1, 8' fixture because it would been too close to my hanging gas furnace and I was sure that would be a problem in the fall, winter and early spring.

Each row has its own switch. So I turn on only what I need and yet, I can light the entire shop when I desire.

Everybody who has come into the shop has commented positively about the lighting and it works well with my 60 year old eyes.

Sorry for the slow reply. Thanks for the input. I've decided to run 5 rows (24' width), each row containing 2-8' fixtures and 1-4' fixture. This should give me great lighting. I do plan on switching each row for the best control. Thanks again. Steve

[Steve Milito]

Tom,

In the example he's using 4 32watt T-8 - 4' bulbs watt in 8' fixtures and from the article:

The footcandle was previously defined as lumens of light per square foot. To provide 100 footcandles we need 100 lumens per square foot times 1500 square feet, or 150,000 lumens at the work surface. Since only half of the lumens on the ceiling make it down to the work surface we need twice as many on the ceiling, or 300,000 lm. Assuming a 32w T8 lamp rated at 2800 lm we need 300,000 lumens divided by 2800 lumens = 107 lamps. Each 8’ fixture contains 4 lamps so we need 27 fixtures. In math terms this takes the form:



# fixtures = (desired fc) x (shop area) x (2) / (lumens per lamp) x (# lamps per fixture)
= (100 fc) x (1500 sq. ft.) x (2) / (2800 lumens) x (4) = 27 fixtures

He's talking 100 lumens/ sq. ft. at the work surface not at the light fixture.

In googling around it seems 8' T8 lamps are 5000 - 6000 lumens. Thus, it appears to me that you need 27 fixtures if you go with 4' fixtures, or 1/2 that number if you go with 8' fixtures.

[Jack Lindsey]

In googling around it seems 8' T8 lamps are 5000 - 6000 lumens. Thus, it appears to me that you need 27 fixtures if you go with 4' fixtures, or 1/2 that number if you go with 8' fixtures.

Steve - the example is based on 8' fixtures with four 4' lamps per fixture. One 8' lamp will produce about the same number of lumens as two 4' lamps so an 8' fixture with two 8' lamps will produce about the same lighting level as an 8' fixture with four 4' lamps. You will still need 27 fixtures. If you are thinking of using 8' fixtures with four 8' lamps per fixture then you could reduce the number of fixture by 50% but that will require a different mounting arrangement and you may affect the performance of the system and significantly increase the installation cost.