Ah. So that changes the numbers a bit. 1 case isn’t enough to do all of CA, then.
CA has 11 fixtures, 3 totally dead, and 1 sad/pathetic/flickering. So one case would fix the bad ones, and upgrade 2 other fixtures.
Also, the price I gave was for the cheapest of the T8 bulbs. The “1000Kelvin” makes me twitch. Is that a real lighting measurement, or are they just jacking around with names?
It’s for real. Refers to “light temperature” or “quality” or…whatever…
No idea what we’ve been buying, but you want them all to be the same in 1 room, in my opinion…
Color temperature is one of two primary characteristics of interest for both LED and fluorescent bulbs. Color temperature as shown above is how the color balance appears, more “warm”, yellow, incandescent feel towards the lower K rated bulbs, or more brilliant white, or bluish, or “cold” white towards the higher K end of the spectrum.
But the other factor is CRI (Color Rendering Index). This is supposed to indicate how well our eyes can perceive the color of illuminated objects compared to sunlight or incandescent lighting. Those sources have continuous spectrum to interact with the pigments or dyes in objects, and the resulting light to interact with our eyes. But LED or fluorescent lights usually only emit a few wavelengths. And these can spaced, and proportioned to form any color balance, but they can be really poor at rendering colors in ways we can accurately perceive. Especially for shades of red. Higher CRI should always be better.
I’d say 2 25 bulb cases is a start for the space. We don exactly have folks lining up to change them.
And really, that should be enough to do CA and Metal Shop. Other areas can speak up (and maybe man up).
Just to further prove my ignorance…
can you put T8’s in a T12 fixture and/or vice versa?
Meaning, is it acceptable to buy all T8’s if we’re not SURE they all contain T8’s now (or do we know that?)?
Googled it.
at least 2 sites near the top of the “GOOGLENEVERLIESTOME” return say YES, you can totally stick T8’s into T12 fixtures. 
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Well considering we are changing the tombstones, it wouldn’t matter.
Color temperature as other have explained. 4000K or 5000K are pretty much the standard for workplace lighting. Any warmer (perversely a lower K value) and your eyes have difficulty focusing, any cooler (higher K value) and the blue dominates at the expense of red and yellow color rendering.
If there’s demand for high precision color rendering anywhere in the space, that’s likely best done with task lighting chosen for the specific task at hand.
This is generally true, but not terribly important for how we perceive color.
Here’s a general representation of how various light sources emit by wavelength; specific LED or fluorescent products can vary from the charts below:
The fun thing about noon daylight is that it’s generally in the 5500K range, which under artificial lighting scenarios we perceive to be blue-ish but in the context of the bright sun forcing our pupils to constrict we perceive it as a properly neutral white balance. The atmosphere can greatly alter the color temperature and spectrum composition of sunlight.
While many of us love the comforting warmth of incandescent, its rendition of greens is meh and anything shorter wavelength than cyan is poor despite having near-perfect CRI by definition as a blackbody radiator. There are reasons other than energy efficiency that incandescent lamps are not used in most workplaces.
While there are numerous other ways to get white light from LED (RGB, R+blue-pumped-Green+B, ZnSe, NUV pumped), the dominant topology uses a blue die to pump a yellow phosphor that converts a large fraction of the blue to lower wavelengths, thus the blue spike in its spectrum. The specific combination of blue die and phosphor formulation can greatly alter the color temperature and the CRI / color rendition accuracy of the final product.
Fluorescent is somewhat similar to LED in the sense that uses a pump to drive a white phosphor, however its pump is UV and its phosphor tends to emit in relatively discrete bands. High CRI fluorescent products have nonetheless been a real product for decades.
Some ten plus years ago, LED lighting had such garbage CRI / color rendition that it wasn’t worth publishing (sub-60 was common and the color temperatures were angry blue obscenities north of 7000K). Nowadays even low-end LED lighting products have ~80 CRI; the Hyperikon tubes I linked is 85 CRI. Going any higher for bulk lighting of so much otherwise general-use space probably isn’t worth the markedly greater cost; specific task lighting will solve that need since odds are such work demands more lux than the overhead lights are providing anyway.
And it totally makes sense that you can retrofit the smaller diameter T8 where the larger diameter T12 once resided. For some reason, I was thinking their diameters were the other way around.
Does your count include the sewing room? Or just the bigger open space?
And we have the wiring retrofit parts to go with 50 bulbs?
We have the wiring, not sure how many tombstones we have.
Since todays the last day to slap stuff on the Board agenda, I’ll just add an estimate after Beth weighs in on the number of tubes needed. Or wait until I get there mid-afternoon and do a count of my own to include the back half of the metal shop. We’ll always need tombstones, so even if we overbought those to start, there will be more needed down the line. (lecture hall, smaller classrooms, yadda-yadda.
I’d be willing to bet that the kid who helped with phase 1 of the filter-hanging would be down for helping with the lighting work in both metal and CA. CA will definitely be easier to deal with than the rest of metal, since the ceiling is only eight feet from the floor vs. whatever it is elsewhere in the space.
