LED lighting lumens / square foot

[Refuse1]

I have 2 workshops that are each 40 x 25 with 10' ceilings. White metal walls and white metal ceilings.

I am going to install LED lights in the spring and plan to buy the Costco Feit 3700 lumen fixtures when they go on sale later this month for $31.99.

I should say at this point that I am going to use LED lighting because I want to. The pro's & con's have been beat to death and do not belong in this thread.

It is my understanding from reading here on GJ that the general rule of thumb is to shoot for around 100 lumens per square foot. I know many have less and many have more, but this seems to be somewhere in the ballpark. I have also read that this figure is based on florescent lighting technology and that some of the 100 lumens is lost and not effective.

So with all that said, does anyone have experience or knowledge of lumens per square foot needed to adequately light a workshop with LED tube style fixtures ? I would have to assume it would be something less than 100, but I'm just looking for advise from folks that know more about this. 4 rows of 5 (4') fixtures in each space will be 74 lumens per foot. 5 rows of 5 fixtures would be 92.5 lumens per foot. I'm leaning toward more is better, but thought I'd look for suggestions.

Thanks,

 

[iigs]

I'm curious about this too. I'd love to hear if anyone has ever thought they had too many lumens per square foot, and how many that was.

 

[Refuse1]

I think I read somewhere that 15-20% of the light produced with conventional florescent tube lights is wasted. I think the LED bulbs are better at "aiming" the light where you want it.

 

[Showkey]

^^^^^^^^^
Sounds like your opening the pro and cons door

 

[Autorotica]

4 rows of 5 (4') fixtures in each space will be 740 lumens per foot. 5 rows of 5 fixtures would be 925 lumens per foot.
Thanks,

Your decimal is in the wrong place. 74 and 92 lumens per foot.

I posted a pic of those exact lights in my shed in another thread and my lighting density is 28 lumens per foot.

Chris

 

[Platonic Solid]

See Page 2 near the bottom: https://www.wbdg.org/pdfs/usace_lightinglevels.pdf
Vehicle construction/Maintenance = 500 - 1000 Lux = 50 - 100 Lm = 50 - 100Fc per square ft.
Now if only Feit were nice enough to provide an IES file you'd be able to do this right.

 

[Showkey]

Real life comparison ......goal was to get 750 LUX on the table saw. 8' ceiling table 36" off the floor.

Measured 750 LUX with 4 T8 2600 lumen bulbs ballast factor unknown. Menards 4 tube fixture. Sylvania bulbs 4100 temp. The floor near the saw measured 250 LUX.

To get 1000 LUX for close work on a 40" tall bench need 4 T8 2600 lumen bulbs 36" from the work surface. Reflector fixtures ballast factor unknown.

I was at Costco the other day and measured the LUX on one fixture in the dispaly. Unfortunately I do not remember the values and it was way less than scientific .........but I think the OP will need a truck load of those fixtures for a shop area 40x25-10 to 500-750 LUX.

Only way to know........is try them as others have stated.

 

[Refuse1]

Auto, Thanks for catching my decimal error. You are right, it's 74 & 92.

Guess I'll shoot for 92 and see what happens.

Thanks to all for the thoughts & opinions.

 

[Electric_Light]

Which weighs more
A pound of lead or a pound of feathers?

The lead exerts more localized pressure.

If you're measuring lumens on the floor I don't think those lumens care from whence they came. Cfl, candlelight, the house next door burning down, led....

Any other lumens are subject to sales department hype and ideal conditions.

Buy too many of the lights. Return extras if you don't need them.
You might be wearing auto change glasses. You might block some with cabinets. There is no answer to lumens other than give some lumens a test drive.

The lumen compares with gallons per minute from a shower head. A shower head with the same flow rate and beam width can have quite a few different characteristics. LED fixtures using an adequate diffuser can behave like fluorescent tubes, but the ones with visible LED chips produce very hard light.
This explains soft vs hard light and in between.
http://ricksieminski.com/tag/egg/

 

[Refuse1]

Thanks Electric Light.