Fluorescent light fixture source.

[jonmulzer]

'T-' may as well be '1/8"x'. A T-12 bulb is 1 1/2", T-8 is 1", etc. The smaller diameter the bulb, the more efficient it is and the more light it puts out. A 4' T-12 uses ~40 watts of energy while a T-8 uses ~32 watts, but the T-8 puts out more lumens. Same when you go to T-5.

[iceman61]

Is there any harm in installing the lights directly to the ceiling without using the chain? I'm wondering if there will be an issues with overheating since they have reflectors and there will be no air circulation above the light.

I installed mine directly against the ceiling & no problems yet.

[ryan.s]

I installed mine directly against the ceiling & no problems yet.

Thanks iceman that's good to know. How long have you had them that way?

[LarryG]

I installed my fixtures by screwing them to the 3/4" thick attic decking, with 1/2" MDF spacer blocks between the decking and fixture to provide a little room for air circulation. The ballast gets pretty warm but not hot, and doesn't seem to be any warmer than the chain-hung fixtures I had in my previous shop.

[Tom Slick]

with electronic ballasts there are no issues installing them directly on the ceiling. the magnetic ballasts get quite hot so there is an issue with those not having enough air curculation.

[pacwind3]

I guess this is a new one to me. What's a T-8 and a T-12 bulb?
Nevermind, I found the answer.