# Vaulted Ceiling - Fluorescent Lights



## JKBogle (May 10, 2010)

Hi Fellas!

So my shop has a vaulted ceiling. Basically, I insulated between the roof rafters, covered the rafters with unfinished tongue and groove and now would like to finish it off with surface mount lights. The lights I plan on using are 2' x 4', T-12 florescent lights, each with 4 - 4' long bulbs in it.

I think it would look pretty sharp mounting the lights right to the angled ceiling but Im concerned that the main amount of light given off by the lights will be in the air above me instead of on my work surface.

What do you guys think - mount the lights to the angled ceiling or hang them flat using chain or something.


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## intelligen (Dec 28, 2009)

It will be easier to get a consistent, even light dispersal pattern if all the fixtures are coplanar and evenly-spaced. But if the ceiling has only a slight slope, maybe it won't make much difference. If you have any ceiling joists running horizontally below the lights, keep in mind that those will cast shadows. Also, the higher you hang the lights, generally the more light you'll need in order to get the same level of illumination at the floor and your work areas. If you're putting up the lights yourself and if you get the type of fixture that can be hung by a chain, you can always try hanging them both ways to see which one you like best.

As far as your choice of fixtures and bulbs, consider getting T8 or T5 instead of T12; they produce more light per watt than T12. Typically you replace a 4-bulb T12 fixture with a 3-bulb T8 fixture. T8 will give you the most bang for your buck, and you can run a comparison here: http://www.leviton.com/OA_HTML/SectionDisplay.jsp?section=54414


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## patron (Apr 2, 2009)

the light should criss-cross itself somewhat
off of the reflector
as it shines down
the tubes themselves
just shine in all directions

shouldn't be a problem


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## bondogaposis (Dec 18, 2011)

The angle of the lights should not matter but the intensity of the light will diminish inversely proportional to square of the distance from the light source. Which means that if you have a light bulb 4' from your work surface and you move it to 8' feet away you will only have 1/4 of the light reaching the work surface than before you moved it. To compensate you have to add more lights or increase the bulb wattage. So the extra distance of having the lights in the ceiling may cause you to add more lights to get the same amount of light to your work area as the hanging lights would. Only you can decide if the trade off in the cost of the lights and additional electricity is worth it. Look up "inverse square law" to see the science behind my point here.


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## JKBogle (May 10, 2010)

Bondo the beauty of your statement is that I am familiar with using inverse square to calculate the proportionate diminished effect of forces other than what we we talking about. Now that you mention it, it makes complete sense that you could also apply it to light fixtures. Inverse square is a really cool way of using simple geometry to problem solve. Thank you!!!


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## ElChe (Sep 28, 2014)

If I knew shop lighting would require geometry I would have stuck to bowling.


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## JKBogle (May 10, 2010)

Che, I've always wanted to make a table or something from bowling lane flooring.


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## TheFridge (May 1, 2014)

Don't use t12 unless it's free.


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