With summer here, I've been less and less satisfied with the output and shadowing that my workbench light casts. When I'm stuck in the basement working at the bench, it always pains me to see how nice it is outside. The only logical answer: Build an indoor sun.
I looked at what modern lighting options exist, and was surprised at how much I didn't know. There are a LOT of ways to light an area, with many strengths and weaknesses associated with each type. High intensity discharge (Also know as HID lights. Both metal halide and high pressure sodium lights fall under this category), incandescent, fluorescent, LED, the list goes on. I quickly narrow it down to a T5 fluorescent, for the following reasons:
1. Low operating temperature. All HID and incandescent lights get very hot, and I didn't really like the thought of cooking the back of my head as I worked. T5s stay relatively cool.
2. High efficiency and lumen maintenance. Although T5s are not quite as efficient as HID lights, they have much better lumen maintenance. Lumen maintenance compares the amount of light produced from a light source when it is brand new to the amount of light output at a specific time in the future. You can view lumen maintenance curves for different bulbs, which was quite useful for making my decision.
3. Wide spread, low shadowing. Because they light emitting surface is so large, shadowing is not a problem with fluorescent lights. Also provides more even coverage over a given area.
4. Cost. The bulbs are cheap and easy to replace individually, and widely available.
Now that I knew a T5 was the type of bulb I wanted, I looked at what was commercially available. Most T5 light are simply put in a one piece housing with a white interior to reflect some of that light downward. As you step up to more advanced (and more expensive) fixtures, individual reflectors are used around each bulb to maximize the amount of light cast downward, thus increasing the overall efficiency of the fixture greatly. These advanced fixtures cost $500 and up for the amount of output I was looking for, which led me to start designing my own. I used 4 ballasts with 12 4 foot high output T5 bulbs, which emits around 60,000 lumens while drawing roughly 700 watts. Compare that to a 100 watt incandescent, which only puts out approximately 1700 lumens. I also installed switches to turn on different banks of bulbs, so I could preserve energy when I didn't need full output.
In the next step, I'll breakdown what's needed and how much it costs.
Step 1: Parts Breakdown
I saved some money buying many parts locally, but most of the components are easy to find in stores or online.
2 pieces aluminum angle. These will be the end pieces that the bulb sockets and reflectors attach to. I used 2" by 2" angle that was 1/8" thick, and 36" long. It was plenty sturdy, you could definitely use something smaller or thinner. Bought at my local metal yard for $15
1 piece aluminum channel. This is the piece that the aluminum angles attach to, and will also be used to cradle the ballasts. I actually found a scrap piece at a salvage yard for less than $5, but channel shouldn't be hard to find. It needs to be wide enough to hold the ballasts you are using, but it doesn't need to be that thick. My piece is 3" wide, 2" tall, 46" long, and a whopping 1/4" thick. If I was to buy the channel new, I would go 1/8".
1 small piece of aluminum sheet. I used this piece to cover the switches mounted in the aluminum channel, as I didn't want anyone inadvertently reaching behind them and getting shocked. My piece was 1/16", 3.5" by 6", cost $2
Reflectors ($160 as built, $90 if you learn from my mistakes):
12 reflectors. This can get expensive, depending on what you use. I actually used 3 different types or reflectors to compare overall output and spread. 4 Tek II reflectors for $70, 4 IceCap reflectors for $60, and 4 generic 3M reflectors for $30. Bought the Tek and IceCap reflectors from an aquarium supply store, and the 3M reflectors online. I took a side profile photo of all the reflectors, on the left is the IceCap, middle is Tek, and right is 3M. If I was to do it over, I would use all generic 3M reflectors, as they offer only slightly decreased output for a much lower cost. $160 total, but could be done for $90
Electrical components ($132):
Ballasts. I looked for secondhand ballasts online, and bought two different pairs, so 4 ballasts total. Both came prewired, I just had to extend some of the wires and shorten others to keep things clean. Two power 4 bulbs, and two power 2 bulbs. The 4 bulb ballasts were $20 each, 2 bulb ballasts $15. $70 total.
24 T5 bulb sockets. Bought from a local electrical supply warehouse for $20
Switches. I used 3 SPST switches, each was $2, $6 total.
Power cord. Had an extra 3 conductor cord that I terminated myself, but any standard power cord that can handle 700 watts will be fine. A computer IEC cord would be perfect if you have one.
Bulbs. I bought some cool white bulbs online for $3 each, $36 total.
Nuts and Bolts ($4):
26 8-32 bolts, 1/4 long. 24 are for attaching the reflectors to the end pieces, the other 2 attach the aluminum cover sheet over the switches. $2
4 1/4" bolts, 1/2" long. Used to attach the end angle pieces to the main channel. $0.50
4 1/4 bolts, 2" long. Used to secure the ballast to channel. $0.50
8 1/4 washers and nuts for the above bolts, $1
Strain relief for power cord $.50
Paint, not necessary but fun. Really fun if you decide to go fluorescent green like I did. $6
Total cost: $324.50 as built, $254.50 for all 3M reflectors.
Step 2: Frame
I've attached a SketchUp file with the exact frame dimensions and cuts that I made, use as a supplement to these instructions.
I cut the aluminum angle and channel to length (36" for the angle, 46" for the channel) using a bandsaw, and cleaned things up with some sandpaper. Because my channel was so thick, I also cut the last inch off the sidewalls at the ends. This allows the innermost bulb sockets to be inserted into the angled channel without being obstructed by the channel. It also lets the wire from the ballasts to not protrude from the end, and instead stay in the middle of the end pieces.
To finish the channel, I drilled and tapped the holes to attached the end pieces (1st photo), and also drilled and tapped two small 8-32 holes in the middle for the top cover (2nd photo). Four holes to mount the ballasts, three 1/2" holes for the switches, and the channel is complete. You might notice that my channel has a few additional holes, this is due to the fact that I saved it from the scrap yard.
The end pieces take some time and patience with a Dremel. I spaced each square cutout 2 3/4" apart, with the outer squares centered 2 7/8" away from the outer edges. I traced them with a pen, cut them with a small grinding wheel, and cleaned each up with a file. Overall, I managed to get things pretty clean, thanks especially to the file. I drilled and tapped 24 holes for mounting the reflectors to, located 1/4" from the edge.
With the metalworking complete, I decided to paint the frame fluorescent green (I mean, they are fluorescent lights right?). Figured I could spice up the work area with some bright colors, this is of course optional.
Once the paint is dry, assemble using the four 1/2" bolts, but only hand tighten. Mount the reflectors using the 24 8-32" bolts, once the reflectors are installed you can fully tighten the 1/2" bolts.
With the main framework complete, we move on to the electrical portion!
Step 3: It's Electric
Using four ballasts complicated things a little unnecessarily, three would make things a bit easier. I started by installing the switches and sockets. The switches used little knurled nuts that I hand tightened, and the sockets snapped right into place. Before installing the ballasts, make a quick sketch of the schematic pictured on the ballast. I stacked the ballasts on top of each other so that they would fit, and snugged them down with four 2" bolts.
Don't be too intimidated by the wiring photos, it's actually relatively straightforward. Since most come pre-wired, its just a matter or routing them to their correct socket or switch. Follow the schematic, route the primaries to their associated switch, and everything will work perfectly. Took me a couple hours, but it we together without any problems. I wired the power cord hot to one side of the switches, the neutral directly to the ballasts, and the earth to chassis ground.
Once all wired up, I routed the power cord through the top cover, and installed the strain relief. Terminated the cord with a plug, install your choice of 4 foot bulbs, and it's ready to fire up!
Step 4: In Use
Each switch controls 4 lights, starting with the bulbs in the middle. Did a quick photo sequence showing the first time I power it up. It is INCREDIBLY bright. I can't even look at this thing without straining my eyes, but when it's above the bench it's perfect. Balanced, natural light, that makes me miss the sun a little less. Enjoy!