Garage Shop Fluorescent Lighting

baumgrenzeNovember 26, 2011

I'm hoping to learn from someone who knows more about fluorescent lighting than I've managed to accumulate through web searching.

I have an unheated garage workshop on the San Francisco peninsula. In the winter it is often around 50F, in the summer, especially near the ceiling where my lighting is installed, it can get quite warm. I gather from information at the Lighting Research Center at Rensselaer Polytechnic Institute website, the smaller the diameter of a fluorescent tube, the narrower its performance profile as a function of temperature. See:

At 50F, a T8 bulb is down to 75% output and a T5 is down to 40%. The optimum temperature for a T8 is ~75F and for a T5 it is 95F. See the thumbnail below from ImageShack:


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I did not find a similar graph for T12 bulbs, but suspect that it is shifted slightly to lower temperatures and is even less steep in its falloff.

I am accustomed to the light output of two ancient 4 bulb 40W fixtures equipped with magnetic ballasts that require starters. I am ready to scrap these. One ballast overheated recently and I've not replaced it.

I understand that the government has mandated the elimination of magnetic ballasts. See:;hl=en&source=hp&biw=1024&bih=587&q=%22magnetic+ballast%22+phase+out&btnG=Google+Search&gbv=2

There seems to be a move to eliminate the T12 bulb in favor of the T8, but I doubt this will be important in my working lifetime (~10 years at best.) Much of the attention seems to be focused on lumens/watt efficiency and not total lumens per fixture, especially over a range of ambient temperatures.

I have several 40W T12 fixtures, two 2-bulb units with electronic ballasts and many single lamp strip lights with magnetic ballasts. I understand that with T8 electronic ballasts installed, these fixtures would allow the use of T8 bulbs.

Does it make sense to move from T12 to T8 by changing out all of my ballasts?

Does it make sense for me to replace the T12 magnetic ballasts in my strip lights, or should I leave well enough alone and just install them as needed? I do not want to go to unneeded expense only to find that I am getting less light for my aging eyes than I now have.




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This was already posted on Friday. And received some responses. Why the duplicate post? The forum requests no duplicate posts.

    Bookmark   November 26, 2011 at 10:13AM
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I apologize. It was not intentional. If the duplicate can be removed easily, please do so.

I had house guests Tuesday through this morning and was trying to fit in what work and research I could without being impolite to them.

I am trying to understand what I might have done. I am confused by the time stamps on this thread. As it stands, my post is stamped "Sat, Nov 26, 11 at 1:47" and your observation that I posted a duplicate post is stamped "Sat, Nov 26, 11 at 10:13. My history shows that I visited the forum last night at 10:47 PM. I had an early morning scheduled and it was already late. I quickly checked the responses I found and decided I would wait until today to say thanks for what I found. I have a project to complete with an early Monday morning deadline, so I will be 'offline' until that is complete.

Thanks for your input.


    Bookmark   November 26, 2011 at 4:28PM
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Friday post.

Here is a link that might be useful: Earlier post

    Bookmark   November 26, 2011 at 6:28PM
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