|Forum topic by JBrow||posted 01-06-2016 02:23 AM||1240 views||1 time favorited||21 replies|
01-06-2016 02:23 AM
Problem. In August 2015, I purchased the CV 1800 Cyclone Dust Collector. Therefore installation of 6” duct work throughout my 2 car attached garage workshop was needed. The workshop is about 450 square feet with an 8’ 5” high ceiling. Since there are trusses running every which way, installing duct work in the attic was not an option. The duct work had to go on the ceiling.
There were 14 2-tube T-12 florescent light fixtures (the really cheap $10 fixtures with magnetic ballasts bought 20 years ago) mounted in rows with three or four 4-foot fixtures in a row. The rows were mounted 4 feet apart. Options for providing a duct work path were 1) relocate some light fixtures to make way for the duct work, 2) reconfigure the lights completely, or 3) replace them. These lights performed ok, but struggled in the winter when the shop was cooler. They also provided adequate light in the workshop and were probably about as efficient as one could get when purchased.
Attempting to derive specifications for the 20 year old fixtures is problematic at best. I estimate that power consumption, including that of the original magnetic ballasts, is about 150 – 170 watts per fixture, including the two 4’ 40 watt lamps. The Lumen Designer Output is about 2300 lumens per lamp times 2 lamps equals total output of about 4600 lumens. Lumen has become the standard for defining light output of a lamp. Lumen Designer Output is light output produced after 40% of the lamp’s expected life has been used (or maybe it is 40% of the expected life remaining – I can’t remember). Anyway, half the lumens are directed upward in any florescent fixture. Therefore downward lumen output of one of these old florescent fixtures is about 4600/2 or 2300 lumens.
Research and Requirements. I researched shop lighting on the internet. I found an article that recommended about 100 lumens (light output) per square foot and several that recommended light in the daylight color temperature range – all related to woodworking shops. I bought into the color temperature recommendation, but had questions regarding the 100 lumen per square foot recommendation. I recently completed a kitchen remodel during which I installed LED recessed lights that provided about 40 lumens per square foot. The kitchen general lighting plan was developed by a lighting designer. The kitchen offers plenty of lighting. I reasoned that the kitchen and woodworking shop had similar lighting requirements. As it turns out and discussed below, 100 lumens per square foot for a workshop is a good standard.
A lamp with a color temperature somewhere in the 5000 to 6500 degree Kelvin is close to sun light in appearance. Color rendering which, if I understand it correctly, is an indication of how well the light interacts with an object to reveal its “true” appearance. The higher the value (CRI on a scale of 0 to 100) translates to better color rendering. For me, color rending was an important consideration because I apply finishes to sample boards in the workshop; however, not as important as light that lets these 60 year old eyes see better.
Material Selection. I decided to scrap the florescent fixtures and replace them with recessed LED lighting. I considered LED strip lamps, but these would present the same problem as the old florescent fixtures, namely they would be in the way of the duct work.
The recessed housings would be in the attic and the workshop is insulated. Therefore, I bought 6” air tight “new work” recessed housings rated for insulation contact. “New work” housings, instead of “old work” housings, were used because I had access to the attic. White trim kits for each recessed housing, were also purchased. The trim kits provide downward reflection for any stray light, offer a finished look, and were inexpensive. The housings and trim kits were bought at my local home center and totaled under $20 per housing.
I found LED spot lamps rated at 26 watts with a temperature of 5600-6800K producing 1900 lumens while offering a Beam Angle up to 120 degrees. The beam angle was important because I wanted light to spread throughout the workshop. A narrow beam angle would result in small puddles of very bright light. I found the LED spot lamps on Amazon and cost about $17 each.
I already had a 6.25” diameter hole saw designed for cutting 6” holes for recessed lights. It has carbide chips embedded in the cutting diameter. It was purchased at Home Depot.
Lighting Plan. I drew a scale drawing floor plan of the workshop showing machine placement and including the path of the duct work. The location of each LED spot light was placed on the drawing, represented by circles. Circles were drawn on the diagram at locations over or near critical work areas such as the workbench, table saw, etc. and located off of the path of the duct work.
The center of each circle represented the center of the recessed lamp. The circle perimeter represented 20% of the total light from one fixture that would illuminate surfaces that are 36” from the floor. The height 36” was chosen because most work occurs more or less at this height. I calculated that the diameter of the light pool from one LED lamp at 36” was 225 inches at a 120 degree beam angle. The diameter of the circles was 20% of 225” or 45”. Now, circles with diameters of 45” were arranged on the shop diagram, one circle for each recessed light. Each circle touched the perimeter of an adjacent circle. This arrangement ensured that areas not directly below a lamp would be illuminated by two or more lamps. So what does all this gobbly goop mean? In the end, the recessed lights are about 5’ from each other.
After drawing all these circles on the workshop plan, I counted the circles to determine the number of recessed fixtures needed, which was 12.
Since this lighting upgrade was expensive and occurring at a time when further expenses for dust collection were anticipated, I decided to only equip ½ the workshop with LED recessed lights. The old florescent fixtures were installed in the half the garage that is mostly blocked by the garage door in the open position. The old florescent fixtures are on a separate existing circuit from the recessed lights. Most of the machinery is located in the half of the garage where LED lamps were planned.
Installation. Satisfied with the lighting plan, work began. I turned off the breaker and removed all the old florescent fixtures. All florescent fixtures except for four that would be re-installed in the front of the shop at the garage door were scrapped. I recycled the florescent tubes, since these are said to contain mercury.
The position of each recessed light was marked on the ceiling. Since a tape measure flops all over the place, I cut strips of wood that were then clamped together with spring clamps to represent the distances from the referenced back and side walls as specified in the workshop plan. One end of the clamped strips was placed against the referenced wall to discover the correct distance from the wall at the opposite end of the clamped strips.
Then the attic was checked to ensure there were no obstructions that would prevent placement of the recessed housing. Adjustments in the light positions were made when needed, usually by only a couple of inches.
With the final positions marked, holes were cut for each recessed housing. Then electric cable was run to each recessed light. Then I entered the attic, contorting myself into positions I had not been in for years, and installed the housing and made the electrical connections. I picked up power for the circuit from the drop used to power the old lights. The circuit was tested before powering up, Trim Kits and LED lamps were installed, and I was done. Well except for the test of turning the lights on.
Results. Based on the back of the envelope calculations I made above, power consumption of 1500 watts (150 watts x 10 old fixtures that were replaced) was reduced to 312 watts (26 watts x 12 LED lamps). The recessed LED lights consume 20% of the power that the old florescent fixtures consumed.
There is a slight reduction in lumens flooding the shop. The old fixtures produced 23,000 usable lumens (2300 usable lumens x 10 old fixtures). The 12 recessed fixtures produce 22,800 lumens (1900 lumens x 12 recessed lamps). This is about 100 lumens per square foot and in line with shop lighting recommendation discovered during the planning.
The LED recessed lights perform extremely well. There is a less than ½ second delay from flipping the switch and light flooding the shop. The LED lamps do not seem to mind cooler temperatures. The workshop is a good bit brighter than it was prior to the installation. I believe that the brighter workshop is due to the higher color temperature of the light, not simply the lumens emitted. Others who have entered the workshop after the upgrade have all commented that the shop is bright.
The area around the garage door continues to be illuminated from the old florescent fixtures. At some point, I may replace these old fixtures with 4’ LED strip lights, which directs light downward only, are very efficient, long lasting, and offer a range of color temperatures. However, these are expensive at about $100 or more per fixture. If I upgrade in this area, it will be when prices come down a bit more.
Lastly, there are a few spots that are dim. These dim areas are mainly storage areas and there is adequate light in these areas. Based on the lighting plan, I thought these areas would offer insufficient light for detailed work; but then I do little to no work in these areas. However, I may add additional recessed fixtures in the future, but for now these dim areas are not a problem and I am enjoying a well illuminated workshop.
Recommendations. Based on the achieved LED illumination in my shop, I recommend 100 lumens per square foot for shop lighting at a minimum. I would also encourage lighting designs to consider the color temperature of the shop lamps. It seems that color temperature indeed makes a big difference.