Foot Candle Level Required

[Modifieddriver]

I have a list lighting application and the foot candle level recommended for each type.

It shows the following:

auto service garage 60-80
body shop 80-120
wood working shop 60-80
machine shop - medium detail 75-100
machine shop - fine detail 100-200

Based on this and what others here have mentioned, I think 100+ Foot Candles is a number to achieve.

Folks here agree or disagree?

I'll be doing two workshops. One with a white metal ceiling and 10' ceiling. The other will be open, no ceiling, with trusses 12' off the floor and white vinyl backed insulation in the roof and walls.

I've used that on-line Accuity(?) light planning guide. Real helpful, but only if I use the correct Foot Candle #.

 

[pattenp]

IMO definitely no less than 100 lumens. The one with 12' and open ceilings I'd go to 120-150 lumens.

 

[Modifieddriver]

Thanks.

Right now I'm looking at installing:

14 - 6 bulb T5 HO fixtures in the 40'x60'x12'

16 - 4 bulb T5 HO fixtures in the 38'x48'x10'

Hopefully I'll get to use my Ray-Ban's in there.

If I wire them in clusters, I can isolate lighting in the immediate work area I'll be in so I won't have to put a grease fitting on the electric meter.

 

[GShelton]

IMO definitely no less than 100. The one with 12' and open ceilings I'd go to 120-150.

Keep in mind that fc is generally measured at a working height. So when they say 100fc, it will be at the height of a workbench, etc.. Fc is not consistent through the entire range. If it is 100 at the level of the work bench, it will be less at the floor.

My point is that you would not increase fc due to ceiling height or reflectivity, rather you would increase lumens per square foot. Fc would only vary based on the task at hand or your desired light level in a given space.

As for the 100 fc goal, it is what I am shooting for as my general lighting and then I will use specific task lighting where needed.

 

[Modifieddriver]

Keep in mind that fc is generally measured at a working height. So when they say 100fc, it will be at the height of a workbench, etc.. Fc is not consistent through the entire range. If it is 100 at the level of the work bench, it will be less at the floor.

My point is that you would not increase fc due to ceiling height or reflectivity, rather you would increase lumens per square foot. Fc would only vary based on the task at hand or your desired light level in a given space.

As for the 100 fc goal, it is what I am shooting for as my general lighting and then I will use specific task lighting where needed.

Good information.

The program I worked with used 2.5' as a work height. That's pretty good for automotive and fab work.

 

[MoonRise]

100+ lumens/ft2 is a decent lighting level IMHO. But 150 is a 'better' number for precision-type work (short of operating room or brain surgery type things, maybe also jewlery or circuit-board work )

Remember that you'll only get ~80% of the 'rated' lumens out of a bulb/tube (fixture efficiency). And that is when the bulb/tube is new (fluorescent tubes generally 'lose' about 50% of their lumens output over their 'life').

Also, rig/align things for even lighting and no/minimal glare or shadows.

+1 on putting the lightling on several banks so you can turn on what/where you need the light.

Also I strongly suggest using some high CRI tubes. 90+ CRI is nice, 85-86 CRI is usually OK to me, lower than that is NG. IMNSHO

Especially if there is available sunlight coming in (doors, windows, whatever), I'd suggest going with relatively high color temperature like the 5000K tubes ('daylight', full spectrum, high CRI tubes). This way the multiple light sources are relatively 'close' in color temperature and the brain and eyes won't be 'fighting' different color temperatures (gives me a headache or eyestrain when that happens).

You didn't specify which length T5 tubes you were considering. The T5-HO tubes I see range from ~2000 lumens/tube (24W, 21.6" long) up to ~7000 lumens/tube (80-W, 57.1" long).

Let's see, 40' x 60' = 2400 ft2

x 100 lumens/ ft2 = 240,000 'raw target' lumens

x the 'fixture efficiency factor' of 1/80% = 300,000 'tube lumens' desired.

At 150 lumens/ft2 lighting level, that goes up to 450,000 lumens desired.

Your mentioned "14 - 6 tube fixtures" (84 tubes total) using the 'long' T5-HO tubes gets you around 196 lumens/ft2.

If you are using the 'medium' length tubes (54W, 45.2" long) at 5000 lumens/tube, you would come in around 140 lumens/ft2. In your 40x60 building. Pretty good in my book.

 

[pattenp]

Keep in mind that fc is generally measured at a working height. So when they say 100fc, it will be at the height of a workbench, etc.. Fc is not consistent through the entire range. If it is 100 at the level of the work bench, it will be less at the floor.

My point is that you would not increase fc due to ceiling height or reflectivity, rather you would increase lumens per square foot. Fc would only vary based on the task at hand or your desired light level in a given space.

As for the 100 fc goal, it is what I am shooting for as my general lighting and then I will use specific task lighting where needed.

My mistake.. The OP did say foot candles, but I was thinking in lumens. I corrected my post. Thanks.

 

[Modifieddriver]

100+ lumens/ft2 is a decent lighting level IMHO. But 150 is a 'better' number for precision-type work (short of operating room or brain surgery type things, maybe also jewlery or circuit-board work )

Remember that you'll only get ~80% of the 'rated' lumens out of a bulb/tube (fixture efficiency). And that is when the bulb/tube is new (fluorescent tubes generally 'lose' about 50% of their lumens output over their 'life').

Also, rig/align things for even lighting and no/minimal glare or shadows.

+1 on putting the lightling on several banks so you can turn on what/where you need the light.

Also I strongly suggest using some high CRI tubes. 90+ CRI is nice, 85-86 CRI is usually OK to me, lower than that is NG. IMNSHO





Especially if there is available sunlight coming in (doors, windows, whatever), I'd suggest going with relatively high color temperature like the 5000K tubes ('daylight', full spectrum, high CRI tubes). This way the multiple light sources are relatively 'close' in color temperature and the brain and eyes won't be 'fighting' different color temperatures (gives me a headache or eyestrain when that happens).

You didn't specify which length T5 tubes you were considering. The T5-HO tubes I see range from ~2000 lumens/tube (24W, 21.6" long) up to ~7000 lumens/tube (80-W, 57.1" long).

Let's see, 40' x 60' = 2400 ft2

x 100 lumens/ ft2 = 240,000 'raw target' lumens

x the 'fixture efficiency factor' of 1/80% = 300,000 'tube lumens' desired.

At 150 lumens/ft2 lighting level, that goes up to 450,000 lumens desired.

Your mentioned "14 - 6 tube fixtures" (84 tubes total) using the 'long' T5-HO tubes gets you around 196 lumens/ft2.

If you are using the 'medium' length tubes (54W, 45.2" long) at 5000 lumens/tube, you would come in around 140 lumens/ft2. In your 40x60 building. Pretty good in my book.

I'm a rookie at this stuff. Thanks for the advice. Looks like I zeroed in on a good solution.

Oh yeah, I thought all T5 54w HO lamps were about 5,000 lumens and that there were no long bulbs, only the 46.5" (typically called 4 footers, but they're shorter than T8's) long ones?