shop lighting requirments

[jessrice]

Okay, i am getting to doing rough electrical in my shop, and am wanting to figure out how much lighting i am going to want to work comfortably, with out shadows and such in the shop.

The challenge is to determine how many lumens will do what i want so i can figure out what fixtures to use, and then do the rough electrical. I know more is better, as i will have multiple "banks" and can turn some off, but I also don't want to guess what to many are and be wrong, or super over estimate and pay for it in fixtures and wire.

The bay that i am working on is 32 x 36 with 17' ceilings (the other challenge, need a new ladder, but it is high enough for two floors in the other 1/3 rd, so I'll suffer!!)

I have chosen to use 8' t-12 HO fluorescence, and i believe the average lumens per bulb is 7000 at about 110 watts. some more, some less.

so how many do you think I'll need to light up the place to wood work, car repair, weld, etc.

I was thinking 4 banks of 3, each bank having 3 fixtures spaced 2' apart. But could be to much, plus a bank cost me about 250.00 with fixtures, bulbs, and wiring.

I included a diagram for ease of imagination! Any of you help calculate the need lumens to make sure i don't burn out my eyes, or i don't regret putting in more or a different type?

thanks
Jesse

[Russianwolf]

overhead florecents are good for general lighting, but I don't think I would want to go just with them. the mobile work lights work wonders since you can place them as needed since you won't always be standing in the same places.

I would do enough overhead lights to get good general coverage and 3-4 mobile work lights for project areas.

[onedash]

do you have to put them 17' in the air? If you hung them closer to the floor you could probably get rid of the middle row and use regular bulbs and have plenty light to spare.
At 17' though I have no idea how much extra you need to make up for the distance.

[Curly Qsawn]

I think the last Fine Woodworking Shops & Tools annual issue had an article on lighting. I'll look it up when I'm next in the shop. What I remember though is you'll need more fixtures if the author's formula is followed. I agree with others that all flourescent may not be the best choice.

[LCHIEN]

a lot also depends on whether your shop is painted white or not painted at all. White will reflect the ligth and reduce the overall lighting requirements.

[sbs]

I know nothing about lighting design, just taking a SWAG based on the physics...


I have 12 4' 2750 lumen bulbs in a workshop about 15x15 at a height of about 8 ft. It's nice and bright. No extra lighting needed. The walls and floor are white.

A work surface at 3' height is getting 1200 lux. With lights at 17', to get 1200 lux at 3' will require 22000 lumens. So I'd need about 18 of your 8' 7000 lumen bulbs in my 15x15 space if they were at 17' height. Which means about 90 of them in your space.

Looking at my garage instead, where I need less light for working on cars, I have 16 of the same bulbs in a ?20x25? space at about 10' height.

If I used your bulbs at 17' height I'd need about 13 of them to get the same light for my 20x25 space. So that's about 30 bulbs in your space.

I think you need brighter bulbs and/or to drop them down from the ceiling. And you'll probably want to have additional light in the woodworking area.

Again, I may not know what I'm doing...

[Curly Qsawn]

I found the article in my Small Woodworking Shops book or it is FWW issue 154. I'm sure there are many other sources too. 50-100 foot candles is what is recommended. Higher is better with age. 100 foot candles for your square footage by my calculation is 115,200 lumens and your diagram indicates 168,000 lumens. But at 14' distance (assuming roughly a 3' work height) that could be a different requirement. The Tim Taylor in me says you probably need another bank or supplement with some lights at a closer spacing to your work. The spacing of the fixtures is within the guidelines of the article. Depending on what you have against the walls you may want the fixtures closer than the 5' indicated.

[Deadhead]

I have chosen to use 8' t-12 HO fluorescence, and i believe the average lumens per bulb is 7000 at about 110 watts. some more, some less.

Have you considered using T-8's instead of T-12's?

[Tom Slick]

T-8's are the way to go. more energy effecient, brighter, more color choices, bulbs are cheaper, no flickering, better cold weather starting, instant on, parallel bulb wiring...
they are potentially going to stop producing t-12 replacement parts in 2010. It is already against code to install T-12 fixtures in new construction because they don't meet current effeciency standards.

[Thalermade]

You are getting some great ideas. Keep working on the design. Here are a few more things to think about.

Because this is such a tall space I agree that you will need to break this down into General Lighting and then Specific Work Area (or task lighting).

Keep in mind your age and eyes. Older eyes probably need more light.
Do you wear corrective lenses? Or have you had laser eye surgery?

Shop walls, while they need to be light colored, be careful of glossy surfaces which can increase glare.

I think you are on the right track. You should be able to balance quality lighting, cost effectiveness and energy conservation with planning.

Russ

[jessrice]

thanks for all the replies so far,

to answer a few questions,

I have my 12' and 14' garage doors on hight lift tracks so they are only 16" from the ceiling, so that pretty much allows me ceiling mounting the lights.

The walls and ceiling will be drywalled and painted white eventually. As soon as i figure out where to get a drywall lift that goes to 17'.

I have had laser corrected eyes, and am only 35 so my eyes are good now, but wanted to plan for old eyes in the future.

I guess i didnt consider T-8's as the fixtures i have been eyeing are what Home Depot carries for High Output Cold start fixtures. i didnt think that a t8 bulb would put out more lumens that a t12. any suggestions on a 8' long t8 bulb?

I was kinda of avoiding any high pressure, mecury or other "bay lights", as sometimes i pass throught the shop for 2 minutes to grab something and they would never heat up.

Guess it is good i have a little time to work thinkgs out

thanks so far
Jesse

[TheRic]

When you figure out how many light to have wire them up so only a couple strategic ones come on with 1 switch. Use this when you will only be in the shop for a few minutes, just passing thru, etc. No need to turn on 50,000 watts of lights to grab the tape measure off the workbench.

Have other switches turn on the other lights. Maybe mount them higher then the main switch, or in different location(s). For example extra lights over the workbench area. The "bay" lights, work area light could be used, and turned on only when you need them, and know you will be in there for a while.

[wardprobst]

(SNIP)
I was kinda of avoiding any high pressure, mecury or other "bay lights", as sometimes i pass throught the shop for 2 minutes to grab something and they would never heat up.

Guess it is good i have a little time to work thinkgs out

thanks so far
Jesse

Hey Jesse,

I think you are on the right track but I'd consider a few strategically placed incandescents for the times you are passing through the shop. You might want them also for finishing work as the fluorescents are hard to read color under, even the best of them.
DP

[Tom Slick]

t8's are only 4' bulbs, you have to buy 8' long fixtures with 4 4' bulbs. keep in mind that most of the fixtures at HD are junk.
one main thing to consider is you may not be able to buy any parts for T-12s in 3 years if the Department Of Energy backs up their threats.

[Jeffrey Schronce]

I was kinda of avoiding any high pressure, mecury or other "bay lights", as sometimes i pass throught the shop for 2 minutes to grab something and they would never heat up.

They would not have to be on the same switch/circuit.

IMHO T8 is the way to go.