Building a New Woodworking Shop


If the shop itself is one of the most important woodworking tools, lighting for the shop is a pretty high priority. I am no lighting expert, I'm sure there are formulas for determining the amount of light needed for a given environment but I don't know what they are. To compensate and provide a sanity check, I am using a formula derived from my previous shop lighting conditions.

My previous garage shop was about 19 x 20 and had eight 48" fluorescent tubes and seven 100w incandescent fixtures. I have found this to be a pretty suitable lighting level so my first pass at a lighting design is to provide a similar or higher lighting ratio per square foot. This plan does not account for the five windows in the shop which should only make things better in daylight hours.

Old Shop:
Around 122 lumens per square foot.  This is the raw output at the bulb from units that were probably around 3000K in color temperature and a low color rendering index (CRI) of 70-75, maybe less.

New Shop:
Shop area excluding the tractor bay = 27 x 48 or 1296'
Roughly speaking, to provide the same illumination as my old shop I would need (1296 * 122) 158112 total Lumens
A typical T12 fluorescent 40w bulb puts out 2200 Lumens per device
158112 / 2200 = 71.9 bulbs, lets say 36 fixtures to get 122 lumens per foot.

Because I had significant problems during construction with several test T12 and T8 fixtures, I decided to expand my lighting device search.  After some successful testing I finally decided to use compact florescent spiral tubes (CFL); here is the math on that.

Shop area excluding the tractor bay = 27 x 48 or 1296'
16 105w  fixtures each producing 6900 Lumens (16 x 6900 = 110400 Lumens)
32 42w fixtures each producing 2800 Lumens (32 x 2800 = 89600 Lumens)
110400 +  89600  = 200000 Lumens
200k / 1296' = 154 Lumens per foot.

I spread the fixtures out evenly but intermixed the 42w and 105w bulbs with the higher output bulbs placed to advantage common work zones.  In addition, I zoned and interlaced the light switches to control the bulbs.  What that really means is that through four switches there is a North and South zone with the ability to turn on every other light in each zone through one switch.  The image below might convey this more clearly.  The light positions and circuit associations are shown by color.

In good weather and daylight I typically operate the shop with the two big overhead doors open, this provides enough general illumination thus I only need half the lights on in the North end.  During other times I can turn any of the four switches to achieve whatever amount of light I deem necessary.




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