Official Luthiers Forum!

I have been building a shop, garage building is over, selling the house. I used some kind of formula some time back to calculate florescent lighting, it worked great. But now, everything is LED. The total building is 24x32, with a 8x24 sub room in the back. I see online all these LED packages (sort of like florescent) 4 foot length etc. Most are 42 watts. Anybody have advice or know of a calculator I can use?

Mike

This great article by Jack Lindsey at the Sawmill Creek Forum has the formulas.
It works with Fluorescent or LED lighting.

https://sawmillcreek.org/content.php?14 ... id=1973136

Paul

Not sure if this helps, but we have a current count of 36 fixtures in about that same main shop footprint, and plan another 6-7 to double areas that need a little more to eliminate some of the current task lighting. The machine side of the shop has fewer fixtures, but they are located where they fully illuminate the big machines, so the split is about 20-16 machine-side versus bench-side. In the 400 sf storage area, there are 4 fixtures, which provides adequate lighting for the tasks which must be accomplished in that space.

The link includes recommended lighting intensity for types of work, as well as some basic calculations on intensity. In terms of a rough calculation for the shop where I work (just swap out appropriate numbers for your shop and lighting fixtures):

o 36 fixtures x 2 elements per fixture x 2200 lumens per element = 158,000 lumen

o 27 ft x 36 ft = 972 ft^2 less 200 ft^2 for utility/stairwell = 772 ft^2 = 72 m^2

o Average illumination = 158,000 lumen/72m^2 = 2200 lumen/m^2 = 2200 lux

The recommended illumination for detailed drawing work or very detailed mechanical works is 1500-2000 lux, so our average illumination is adequate, but for more demanding tasks requiring a considerable amount of time, higher light levels are desirable, and that is where we are doubling up some fixtures over benches.

https://www.noao.edu/education/QLTkit/A ... indoor.pdf

I hope this helps.

_________________
For the times they are a changin'

- Bob Dylan

All of that is very helpful. Thank you!

Anybody have a recommendation on the actual lighting fixtures?

The Jack Lindsey articles on the net are excellent. I used them to plan uniform lighting in my shop using his upper end intensity. While customers are sometimes startled by it, I still use led task lighting on my two benches for fine work — old eyes.

Sorry, when I setup the new shop, led fixtures were still out of my league, so no experience to share there.


Sent from my iPad using Tapatalk

Yeah, I used same article to do mine a ways back. I guess lumens are lumens, regardless the source. Gonna start calculating. LED has come down a LOT. I found that article that Woodie posted to be exactly what I needed. Task oriented lighting levels. Gives a target to aim at.

I was a Costco a few days ago and they still had the 2 tube 4 footers on sale for around $20. That price is hard to beat. We added seven of them to our shop and they have been a life saver for our old eyes.

This?

https://www.costco.com/Feit-4'-Linkable ... 62723.html

Other considerations are efficiency, color temperature, and the color rendering index. One reason why we moved to direct wire T8/T12 tubes was to avoid the power consumption and down-stream maintenance costs of using tubes which still required a ballast to function. The other advantage is the ability to select tubes with high color temperature and higher CRI for areas where color matching is done.

The T8/T12 replacements we are using are 16 watt units, so fixtures run 32 watt, and the main shop uses 1,152 watts per hour of use. For a 2,500 hour use year, that is 2,880 kilowatt-hours per year, or at the national average of $0.12/kilowatt-hour, about $346 per year. Both for safety and for bank switching, we have the shop wired such that the bench area lighting is on one circuit and the machines on the other shop lighting circuit, so if just one person is in the shop, only one bank is usually switched up, further reducing power use.

While current LED bulbs are usually fairly good on CRI, the next generation of 90+ CRI tubes are slowly entering the market, so we expect to swap those 80+ CRI tubes over some of the bench areas for 90+ CRI bulbs as the prices come down. For color temperature, we use 5000K daylight tubes over benches and mix daylight and lower color temp tubes elsewhere to avoid the shop lighting being too stark. We have so-called full spectrum task lighting where we do color matching, but have found little practical difference between the full spectrum and the daylight LEDs.

One thing I did not fully appreciate before the rewiring of the shop was the ease of flipping two switches and bringing every overhead light in the main shop up, then one more for the storage area. This encourages conservation, as it is no issue to flip those two switches off when taking a short break. The lighting units mentioned may be daisy-chained off a common switched outlet, which has the same effect as wiring all lights on a common circuit. Adding a switch to an outlet is usually pretty easy if not already done.

Another interesting thing I noticed after the lighting upgrades was the lack of need for task lighting over most of the machines and bench areas. While this lighting has been retained, I very seldom see it used, and the next iteration of lighting upgrades will likely eliminate all but the task lighting on the main woodworking bench and band saw (where low angle lighting is needed for surface quality checks and for pencil line visibility on some woods).

_________________
For the times they are a changin'

- Bob Dylan

Looks like the same fixture we bought but I swear the price was a little over $20 each. Frequently the online price at Costco is different from the warehouse price.

Woodie, could you please provide a model number of the units you installed? Maybe a link? Something I can look at?

We used Toggled D-Series 16w 4' 4000K and 5000K T8/T12 direct-wire bulbs in standard T8 ballasted fixtures...each bulb comes with two replacement non-shunted lamp holders, so any T8 or T12 4' fixture will work by stripping out the ballast and existing lamp holders. We salvaged the existing wiring and had lots of excess wire.

Another option is to move to the high output 23w A-series bulbs in the identical 4000K cool white or 5000K daylight rating...these bulbs cost about $18 each versus $12.75, but are 3100 lumen versus 2100 lumens, so will require fewer total fixtures for the same illumination.

https://www.homedepot.com/p/toggled-48-in-Universal-Voltage-T8-16-Watt-5000K-Daylight-Linear-LED-Tube-Light-Bulb-E416-50310/300617201

https://www.homedepot.com/p/toggled-48-in-Universal-Voltage-T8-16-Watt-4000K-Cool-White-Linear-LED-Tube-Light-Bulb-E416-40310/300617206

https://www.homedepot.com/p/toggled-48-in-High-Output-23-Watt-Daylight-T8-T12-LED-Light-Bulb-A423-50230/301230357

https://www.homedepot.com/p/Metalux-40-Watt-2-Light-White-4-ft-Fluorescent-Strip-Light-SSF240/305016129

Total cost fixture is about $50 including tax, so the entire current array of 36 fixtures ran about $1700 (we converted an older 4 bulb fixture and three two bulb fixtures, so saved a bit of money). With breakers, 100' each of 14-2 and 12-2, as well as switches, the entire relighting project came in just under $2K (we ordered the wiring from Amazon...same Southland product, but about 75% of what Home Depot charged.

_________________
For the times they are a changin'

- Bob Dylan

i have 20 fixtures, 5000 lumens per = 100000 lumens

576 sqft = 53.5 m2

100000/53.5 = 1870 lux. im in range. Ty!

I have been slowly switching over to T-8 and this last year to LED.
I find a high failure rate so keep receipts. I am buying shop lights from HD and Lowes.