Garage fluorescent lights

Any idea how to determine how many fluorescent light fixtures I need to lit a garage 22'x22'x8'H?
I am thinking of getting this:
http://www.lightmart.com/index.asp?P...D&ProdID 062
Parabolic Surface Troffer 18 CELL 3x32 T8
I wonder if I need 2 or 4 (or more) of these...any thoughts?
Thanks!
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MiamiCuse wrote:

Per my previous post, I think if I were to use those fixtures I would stick with the 1'x4' version and arrange them around the front and sides of the garage.
nate
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Nate thanks but that would require a lot of extra wiring and cutouts?
MC
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MiamiCuse wrote:

Sure would, but you ever try to see under the hood of a car when the light is in the middle of the ceiling?
nate
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well good point!
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No simple answer. What do you want to do in the garage?
One fixture is plenty to light the area enough to walk through or find that box of stored away garden tools. If you have a workbench, put one over the bench. If you plan to work on cars, put one near the front of the hood so light will get under it a bit.
I have 3 in a similar sized garage. One over the bench, one over my sander on the opposite side, one near the rear. Plenty of light to do anything I want to do.
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There are some different approaches:
1. Suppose you want the garage to be really bright, like classrooms or brighter retail areas.
How much light is that? One fine day I took a light meter to a big-box home center, and brighter areas came up around 1300 lux, which is around 120 footcandles (120 lumens per square foot).
32 watt T8 lamps mostly have "design lumens" (light output when of "average age and condition") around 2700-2800 - I would say 2750 as a "1-size-fits-all".
The ballasts probably have a ballast factor around .88 for 3-lamp fixtures (guesstimate). The fixture could trap and lose 10% of the light. .88 times .9 times 2750 times 3 bulbs is close enough to 6500 lumens. (You could easily get anywhere from 6000 to 7000 lumens from this fixture.)
So, to illuminate a 22 by 22 foot area to 120 footcandles requires 58,080 lumens - requiring 8 or 9 or so of these fixtures.
With some light reflecting around from the walls, etc. and lack of need to have every square foot of the garage quite that bright, you could probably get that garage nice and quite bright with 6 of these fixtures. (Though probably a little short of 120 footcandles in most areas and more than a little short in a few areas)
2. Just get the garage fairly evenly illuminated, as brightly as hallways in office buildings (roughly 50 footcandles / 550 lux):
It appears to me that 4 fixtures will get the garage fairly evenly illuminated. Four 3-lamp fixtures should easily achieve 50 footcandles over nearly all of the garage.
3. See what is done in office areas of office buildings (brighter, maybe around or over 100 footcandles): What I think is common is for a 4-lamp fixture to be in a 2-by-4-foot ceiling panel for every 5 of these panels without fixtures. That is a 4-lamp fixture per 48 square feet. I suspect your 3-lamp fixture is intended to be used in such situations.
It appears to me that doing this for 484 square feet means 10 fixtures, and that sounds to me like overkill for a garage.
I would go with #2 (4 fixtures), and have a little task lighting also.
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I would look for fixtures that have a high amount of diffusion or otherwise are good for lighting wider areas if only 4 are being used, unless you won't have any problems with uneven illumination. Otherwise you could need 9 fixtures to get even illumination.
------------------------------------
- Don Klipstein ( snipped-for-privacy@misty.com)
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Thanks Don very very much for your thoughtful reply. I learned something new everyday.
MC
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MiamiCuse wrote:

Miami, you have a lot of work going on, don't you?
Here is a situation where you let the experts solve your problems for you. Contact a real electric supply in your area. Tell them that you are going to install some lights in your garage and want to get the correct sizes and spacing and ask to talk to their lighting expert. He may be in house, or they may use one of their suppliers. Talk to the person they give you and you will know you have the right guy when he asks you questions like; Do you want to be able to read a newspaper in every area, or do you just want to be able to walk around without bumping into things? How high are the ceilings? What fixtures do you want to use? Etc, etc....
When you talk to this guy, he can design a light layout and spec that will give you what you want. Anyone else, including me, would just be guessing as to your needs and you may or may not be satisfied.
These guys do these designs for a living. Let them solve your problems. They know what they are doing. They know how many lumens each lamp will give you. They know the spread that each light gives at each ceiling heighth. They know how much overlap to allow to achieve the desired results. I don't even WANT to have to know all that stuff, when there are people that do it for me.
--
Robert Allison
Rimshot, Inc.
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Yes Robert I have substantially gutted a 3800SF house so I have been busy. I will try your route too. Thanks!
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HI,
I have a two car / double garage about your size. I have two, eight feet long double flourescent lights mounted in the celing just behind the garage door openers. Each light has two tubes of I think about 65 watts each. I think they are the cheapest ones available at Home depot.
I found this to be sufficient. My ceiling and walls are white. I have managed to change the oxygen sensor in my honda using this lighting no problems.
Best, Mike.
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wrote:

HI,
I have a two car / double garage about your size. I have two, eight feet long double flourescent lights mounted in the celing just behind the garage door openers. Each light has two tubes of I think about 65 watts each. I think they are the cheapest ones available at Home depot.
I found this to be sufficient. My ceiling and walls are white. I have managed to change the oxygen sensor in my honda using this lighting no problems.
Best, Mike.
Thanks Mike.
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I think that's about right. I have a 3-car garage with 4 lights each containing two 4ft T-12 tubes. It's just about adequate -- but only just. It's certainly an improvment over the single 150 watt buld the builder installed ;-)
I didn't think it was worth going for T-8's in a garage.
--
|~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~|
| Malcolm Hoar "The more I practice, the luckier I get". |
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I had the equivalent of four of what what you are suggesting and I replaced it with four 8 foot units and I have been very happy with the results. It is nice and bright and even light. What I had before worked, but was not nearly as nice. Using just two of the units you are talking about would be like a night light to me.
I suggest that you make sure whatever you use is rated for the cold temperatures they may be operating under.
--
Joseph Meehan

Dia \'s Muire duit
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