Even with the new reflectors, I can't imagine the light output being near what the F40T12/U's put out....even the dimmer F34's that are usually used in these. I suppose in a hallway, that might be OK.

Yeah I think that three F17s may have been more appropriate, although I did some math for my grandpa and if I were to retrofit his 4X F40/RS fixtures to 2X F32T8 with 1.18BF ballasts, he'd get more light and save a crazy amount of energy. That's without a reflector though. I personally dislike these specular reflectors. They looks very odd in troffers and on industrials.

Yeah, I guess a retrofit kit that used 3 F17s would have been better, or maybe 2 F17s but with a HBF ballast. I guess they figured the room was overlit since the troffers were spaced every 5' so the reduction in lumens wasn't that apparent. I'll get a pic of the full room. I don't mind the specular reflectors in troffers but they look odd in industrials.

The reason I don't like specular troffer reflectorsis because of the shadows that end up on the diffuser. Ever seen those 2-lamp retrofits for 2X4 troffers? They look terrible IMO. Hmm I think 5ft apart is good. Since the fixture is 30"X30", is the gird ceiling the same? That's odd. Never seen anything other than the normal 2X2, 1X4, 2X4, and occasional 4X4 ceiling tiles.

I see, yeah the specular reflectors do make the troffers look odder than your typical troffer with a white painted reflector. Yeah, the grid is also 30"x30" which is a pretty weird size IMO. I wonder if these lights were custom made too. Then again my school has some other odd ceiling tile sizes. I've seen 18"x60" ceiling tiles and troffers here. The troffers use standard 4' lamps so they have a lengthened metal frame so it'd fit in a 5' opening.

Aside from my school, 1x1, 2x2, 1x4 2x4, and 4x4 are the more common sizes.

I think the tiles only come in 2X2, 2X4, and 4X4 sizes. If you have a 1X4 or 1X2 or any other size you'd probably just have to cut the tiles. I don't know. I can't seem to find a company that makes generic ceiling tiles and Lowe's and Home Depot just sell the common 2X2 and 2X4.

Update, I think they had custom lens doors made up for these, I noticed a bunch of these that were missing lenses got new lenses and doors. They also ordered new louver assemblies for the parabolic ones missing the louver.

Hmm wow! That's a rarity nowadays. Around here they just replace all the fixtures when they start loosing parts. Unfortunately replacing the fixtures tends to be cheaper than getting new diffusers. Good quality diffusers can get really expensive. Especially when it's an older light requiring a custom fit.

Yeah, I'll try to get some pics sometime showing the new style lens and the older style lens. Same thing with the louvers. I think one reason they had custom lenses and lens frames made is probably 30x30 fixtures are kinda rare so it might have been easier to have custom diffusers ordered.

I agree with the costs of replacement diffusers, one of the diffusers from my wraparounds fell and broke (it was over the garage door so I guess it must have vibrated loose) and the price of a replacement is $17. I remember I paid $20 for the entire fixture lol so I guess I'll wait until I find a replacement at Restore or something.

My vaportight diffusers were $19 each, which isn't too bad considering the fixtures are typically around $80-100 new. But two plus $30 Shipping meant I spent close to $70 on two diffusers lol. But my vaportights are complete now! I bought strips at Lowes for them and grabbed latches off other vaportights to make up the six per fixture on mine.

Surprisingly the Ryerson library seems to be in the middle of a LED retrofit the last time I was there. They're keeping the existing fixtures and installing 5000K LED tubes. They're also replacing the prismatic 12 diffuser with a custom 16 cell parabolic louver assembly. I'm guessing they;re only keeping the fixtures because of the oddball 30x30 size. The ceilings in the library are fairly low and the troffers are spaced 5' apart so the switch to LED dosen't look that bad aside from being a bit glary. Looks better than the existing yellowed /741 T8s, although new T8s would probably also look a lot better lol.

Nice they kept the old fixtures and even cooler that they went with parabolic louvers. they would help cut the glare of LEDs better than a diffuser IMO (unless you looked directly up at it, but I've seen troffers that use both parabolic louvers and a prismatic diffuser and those work nice but they look tacky to me, like someone did it as a hack.

Yeah, the custom parabolic louvers are pretty nifty looking. I uploaded a pic of them. Yeah even most factory diffused LED troffers use more of a milky white plastic diffuser instead of a prismatic one. The few that do look fairly glarey. I wonder what a LED troffer might look like with a milk drop dish diffuser though. Seems like it might be better than prismatic 12.

I haven't seen troffers with parabolic louvers and a prismatic diffuser but I've seen ones with parabolic louvers and a clear acrylic cover, probably to make it a enclosed fixture.

The focal point of the LEDs is so small I think the prismatic diffusers are not able to do their job. I have seen LED "puff/cloud" wraparound type fixtures which use the same diffuser material as a drop dish troffer and I have to say the light is very nice. Very diffused with no eye strain. Can't even tell there are LED chips in there aside from the light looking "different" than fluorescent. More a blue-white than a yellow/green-white.

Interesting, I wonder if drop dish diffusers will make a comeback again lol.

Speaking of drop dish fixtures, I saw some 2x2 MV drop dish fixtures last night. They're 400w and have a 4" deep drop dish instead of the 1" deep drop dish that fluorescents have. Unfortunately it seems like 400w is too high for the diffusers as all of them had a hole melted in the centre.

I've seen 2x2 troffers with prismatic acrylic lenses that were drop dish with a slight point in the center. A lot of the Shaw's supermarkets here used them. Never seen an opal 2x2 troffer in person though, HID or fluorescent! I've only seen 1x4 opal drop sign troffers.

I occasionally see them in 50s and early 60s buildings that still have the original lighting. Seems like it was a common thing to use here back then. The ones I've seen almost always used 4xF20 lamps so I guess Ubents weren't common/introduced back then.

Ryerson still has a couple of them in use, retrofitted to 2xF17 lamps using the same kits. I got bored one day and opened one up to check.