I've read most all of the posts here on garage lighting. Some good info. What I haven't seen is info on how many fixtures and the best placement of them. I'm building a 30' x 36' garage with 12' ceilings. I'm going to use T-8 HO fixtures either 4' or 8'. My question is how many and what is the best layout for them?

 

We have a 28x30 and, although I'm not sure of the specific model, used 8ft lights (2 bulbs per unit... each housing has a defuser lense over it) running 2 rows front to back almost the entire length... so 6 lamps per bay. The lights are on 3 separate circuits. One circuit turns one light on per bay, good if you just need to run in the garage, and the other two control the other bays separately. Plenty of light.

When I get back to school I can see if I have pics if you're interested.
Hope this helped,
Tom

 

I just put new lights in my garage. It's alittle smaller than yours at 28' x 32'. I posted a thread here with a link to pics in my gallery. I put nine 8 footers in. With 12' ceilings you are at an advantage because the light will diffuse more than with lower ceilings. You'll want a compromise between functionality and installation difficulty. I think that long rows are relatively simple to install, and will suit your needs well. If I were in your shoes (which I recently was), I would put in 3 rows of four 8 foot two bulb fixtures. I ran the lights lengthwise because I wanted even light when painting cars, and I usually put cars in lengthwise to paint them. You may prefer running them the short way if thats how you usually orient vehicles in there. I would suggest four rows of three fixtures if you want the short way.

You will want the distance from the nearest wall to the first row to be no more than half the distance between the rows of fixtures. This will ensure you get light at the walls, typically where benches and tool boxes are. You may also want a dedicated bench area light. That was my origional plan, but didn't need it with the amount of light I ended up with.

Be sure to make walls and ceiling white, or even better (like I did) get the rigid foil faced insulation sheets that reflect light very well.

 

The cheapest and easiest way to get uniform lighting would be to run 3 continuous rows of 8 foot (4 tube) tandem channel fixtures the long way. Put them at 7.5, 15, and 22.5 feet. Start the row 2 feet out from the perpendicular end wall and run 4 fixtures per row, for a total of 12 fixtures. The advantage of the continuous rows is that you can run your wiring inside the fixtures; this saves a bunch of work, cable clamps, etc. Make sure your ceiling and walls are painted white.

This will get you more than 100 foot-candles of nice, uniform lighting across the entire floor area of the shop. Most retail stores are lit this way. Look up the next time you go shopping for examples of how this is usually done.

If you price out fixtures and tubes, I suspect you will find the 4 tube fixtures using 4 ordinary F32T8 tubes are MUCH cheaper than the 2 tube fixtures using F96T8HO tubes. And the tubes are cheaper too.

With this amount and uniformity of light, you should not need to orient the fixtures parallel to the vehicle for body work, but this is a matter of personal preference. 4 short rows oriented the other way would also work well in terms of overall light.

If you really want to play with this stuff, you can download Lithonia's lighting design software from their website. They have photometric files for all their fixtures. You can lay out a model of the building, tell the software how many fixtures, it will place them "optimally" and then give you a contour map of the resulting lighting levels.

 

This would be great if you want lots of light in the middle of your garage, and less at the walls. Lay out any defuse pattern you want, and you'll see two overlaps in the center, and less toward the walls. Depending on where you park in relation to the lights, you may not get good lighting on the sides of a car with this setup. I wouldn't do it this way. Also, if you do paint (or just want lots of light on the sides), don't just take my word (preference ) for it, take a look at any paint booth out there.

 

I too was going to use fluorescents and then someone told me to just use a couple of Metal Halide lights. My main, tall celing area is about 30 x 28. I put two high bay, 400W Metal Halide fixtures up at about 12 feet. When they are on it is like the shop is in the sunshine.

I did not have to run a large amount of heavy wire. Since they draw less than 3 Amps since they are 220V, you can run very light wire and you are only haning two fixtures.

The Metal Halide bulb life is MUCH longer than fluorescents and there are not NEAR as many bulbs to keep up with. Nothing bothers me much more than a flickering fluorescent.

It's your shop, but all I can say is that I sure am glad that this person put me on to the metal halides.

Good luck,
Doc

 

Now that I think about it, I screwed up in the prior posting. The space from the wall to the first row should be half the space between rows. So with 30 feet and three rows, you want the row positions to be 5 feet, 15 feet, and 20 feet, not what I posted earlier. If you have a workbench along the wall, you might add one extra fixture over it, since the very edge along the wall will be slightly dimmer -- maybe 90 fc.

 

Thanks for all the good information. Keep it coming 'cause I only want to do this once. Don't want to hang the lights and think, "gee, I wish I had done ...

bterry-Haven't seen a paint booth. Are the lights further to the sides or are they mounted on the wall as well as the ceiling?

MBdiagMan: With the metal halide lights and having far fewer fixtures, do you have a problem with shadows? I would think I'd need 4-6 fixtures to prevent lots of shadows.

 

Most often, they will be linear in the upper corners (where the walls meet the ceiling). Some have lights in the walls. Do a Google Image search for "Paint Booth" and you'll get the idea. But please don't think I'm telling you to put the lights in the corners... just lined up lengthwise, and a little toward the walls.

 

I was looking on Lithonia's website and they list high bay and low bay metal halides. What ceiling height is needed for the high bay vs. low bay? I'm thinking about using flouresents for the main lighting and maybe two halides over the workbenches.

 

I have abandoned flouresents as I have aged. At 46 they just dont provide the spectrum I need to read or work. Plus what ever spectrum they start with they loose quickly as they age. I use a 150 W bulb over head in my garage, and several 100 W bulbs on adjacent walls. Nice bright light better than any tube light I have seen at work or home. I just discovered a 200 W bulb at Lowe's the other day and I am thinking of trying that, once I find a suitable fixture. From my experience I also agree with MDdiagman, use anything besides tubes. I work at an aircraft engine plant, and we switched from a kazillion tube lights to MH lights spaced about 40 feet apart, and it is like daylight in there, much easier on the eyes. Good luck hope it works out for you. Now if I can just find a way to make my floor illuminate for working under the truck !