Which color temp for T8 best

[greatkids]

Thanks for all the previous advice; looks like we will be using eight four foot fixtures, each with 6 32 watt T8 bulbs for our 750 sq. ft. shop. Now we need some feedback on the color temp to choose. Basically, there seems to be three choices: the Daylight 6500K at 2750 lumens, Cool White 4100K @2800 lumens, or the Soft White 3000K @2800 lumens. Bearing in mind that each fixture will have six bulbs, what are the pros and cons of the three choices? Thanks in advance.

 

[greatkids]

Or a mix?

 

[williaty]

The 3100K will look pink in a shop environment, so it's straight out.

The 6500K is mainly necessary for color-matching work (which you're not doing) and some people find the light from them very harsh and painful (not everyone), so I'd suggest staying away from those.

The 4100K, provided you select a model with high CRI (greater than 80), is a typical industry choice for shops and engineering, etc. I'd go with that.

 

[greatkids]

"The 4100K, provided you select a model with high CRI (greater than 80)"

er, what's a CRI? I don't see that in any of the bulb spec sheets.

 

[williaty]

Color Rendition Index. It's how well a bulb fakes being a good light source rather than a crappy one. It should be in all of them. If not, I know it's in all of the pages on 1000bulbs.com

 

[bochnak]

I have 3200k and plan on buying 4100k soon. Current bulbs are too yellow....6500k are too expensive for me.

 

[jvitez]

Our eye sees 3000-3500 K as white, but for some reason fluorescents look a ghastly bilious yellow/orange at 2700K, even though incandescents are 2700K. I bought some for the house and immediately returned them. Yuk!

6500K is the color of the pale blue north sky in the middle of winter. It definitely has a bluish look. My preference is 4100. To me it looks white with a hint of blue.

CRI means how close to sunlight does the bulb show colors. It has nothing to do with yellow/white/blue light from the bulb itself, it's how it shows the colors of items being illuminated. Our eye says 85 CRI is really close to sunlight. CRI 100 is sunlight. Incandescents are CRI 100. Much less than 85 and it becomes noticeable. Old "cool white" T12's had a CRI of about 65% which is why they gave everything a greenish-yuk color. If you're painting and paint or stain matching, you'll need high CRI bulbs for over the table you'll be mixing/applying colors, of CRI 95 or better. If not, 85 is just fine.

I would use 4100K CRI 85 bulbs with the highest lumen output for wattage input you can find. Fluorescents maintain about 90% of their lumen output throughout their life. High CRI bulbs produce noticeably less lumen output, ~2200-2400 vs 2800-2950.

 

[williaty]

Our eye sees 3000-3500 K as white, but for some reason fluorescents look a ghastly bilious yellow/orange at 2700K, even though incandescents are 2700K. I bought some for the house and immediately returned them. Yuk!

Our eyes don't see anything as white. Our brains are happy enough to see anything from about 2000K to 8000K as "white" if you don't provide it with a better reference. This is an important distinction. It's commonly accepted to call anything between about 5200K and 6500K "daylight".

6500K is the color of the pale blue north sky in the middle of winter.

Not quite. 6500K is the color temperature of the light coming from a clear sky opposite the sun. It's NOT the color of the sky itself. D65 (6500K, 100CRI) is the standard most often used in the graphics industry because it most closely matches sunlight.

CRI means how close to sunlight does the bulb show colors.

Again, not quite. The CRI is how closely the lamp mimics a perfect blackbody radiator. Fluorescent lamps are discontinuous emitters. This means that they don't actually emit all colors of light. The produce several discreet spikes. The average of these spikes is the color temperature. CRI is how many spikes there are and how short they are, basically. Just 2-3 really tall spikes is a bad (low) CRI. A huge number of closely spaced, short spikes is a good (high) CRI. CRI affects both fatigue and the ability to distinguish similar colors from each other. This is important for sorting through wiring bundles, or reading color-coded diagrams, and other things like that.

Our eye says 85 CRI is really close to sunlight. CRI 100 is sunlight. Incandescents are CRI 100. Much less than 85 and it becomes noticeable. Old "cool white" T12's had a CRI of about 65% which is why they gave everything a greenish-yuk color. If you're painting and paint or stain matching, you'll need high CRI bulbs for over the table you'll be mixing/applying colors, of CRI 95 or better. If not, 85 is just fine.

This is completely wrong and mixed up.

CRI of 100 is a continuous emission spectrum. CRI of 65 would be a very discontinuous (mean it's "missing" a lot of colors of light) source like oldschool fluorescent lamps. The sun is a 100 CRI source because it's a blackbody radiator and produces at least some of almost all wavelengths of light. An incandescent lamp is a 100 CRI source because it is a blackbody radiator and produces at least some of all wavelengths of light. To do things like color matching, telling colors apart, etc, it's important to have a light source that produces all wavelengths of light. This is why higher CRI sources allow you to do better color matching and sort through wiring harnesses better.

There is no direct causation between color temperature and CRI. There's simply a trend that the most work has been put into making bulbs with a high CRI in the color temperature region around 4100K because that's the color temperature preferred by many offices and factories. The research goes where the sales money is.

 

[MoonRise]

Use a high-CRI 'daylight' bulb/tube.

They make things look good-to-decent, unlike low CRI bulb/tubes which make things look like c-r-a-p.

Once you use some 'decent' bulb and tubes, most 'regular' stuff looks like Bleh or makes stuff look like Bleh.

If you will have different light sources available (window, incandescent task lighting, T8 tubes, etc), then try to 'match' them to all be 'daylight' as otherwise you (or at least -I- do) will see a pretty marked color-temperature difference between the differing light sources.

btw, jvitez, our eys/brains can often 'see' a single light source (or the light from that light source) as 'white' if we 'think' it is supposed to be 'white' and it is not too-too far away from actual 'white'. Hence without either a differing color-temperature light source or being pretty aware of it, our eyes/brain usually let us see light from an incan bulb as 'white' and (that nasty green-tinged) light from an isolated CoolWhite fluorescent bulb/tube as also 'white. Put two differing color-temp light sources together and the brain can really no longer 'auto White-Balance' things and most people can then pick up the difference in the color temps. Almost no one is 'fooled' by low-pressure sodium light though, the color temp AND the CRI are both too far 'off' for that to occur. YMMV.

 

[regguy1]

I chose the 6500K 86 CRI bulbs and really like them, excellent light for working.

Garage is a 26' x 30' with 20 48" 2 tube fixtures with plastic diffusor.
They're the HD $20.00 "wrap lights"

It's like daylight in there !

 

[jvitez]

Great pictures regguy1. Thanks.

Williaty: you're obviously in the industry. You give a clearly detailed, scientifically sound explanation. Yet, what did I say that was 'completely wrong and mixed up?" I never said anywhere that CRI is related to colour temperature. In a quick post I was trying to give a middle of the road explanation as to what the different numbers mean, to someone who is asking for help. Sorry if I wasn't as precise as I should have been in my university class.

Anyway, to the OP: I hope these examples help. You might want to buy a couple of each type of bulb (properly called a lamp.....) you're interested in, mount them in one fixture each, and see how you like it. Let us know what you finally decide. Good luck!

 

[Frank The Plumber]

Day light bulbs. Or grow give a good color.

 

[Zeke]

Or a mix?

Absolutely. There have been studies of light color temps in offices that are windowless. People get headaches when things are all one temp. Wherever my wife worked, I always went in on the weekend and installed my own choice of lamps. I placed a small incandescent light on her desk with about a 60 watt and a shade. This variety is beneficial.

Of course, there is no substitute for natural light via windows or skylights. That is until you pull a night shift in an otherwise well lit (but improperly lit) work place.

 

[Falcon67]

I used 6500K in my fixtures. It was a bit "harsh" at first but I liked the brightness and the color of everything. The harsh came probably because I switched from old 4100K T-12s to new T8 stuff. I had 12 4' duals in a 20x24, plus I put dual 6500s at all task lighting or machines. No shadows.

 

[Vicegrip]

Automotive dealerships. I run 4100 in the main shops and offices. 5000 in the paint booths and QC inspection bays. 4100 in the drop lights too. Anything less in the drop lights gets complaints.

 

[Tom McDermott]

Try before you buy. Almost everyone has a different personal preference.

Go to a good store (the type that has the different color temp bulbs on display) and see what you like best. Take along something you will be working on, and see how it looks under the different lights.

I do a lot of woodworking, and brought along some different pieces of wood to see how they looked. Based on that, the 4100K was an easy choice for me, my wife prefers 3500K. A friend likes 6500K.

Try first, buy second.

-- Tom

 

[gnxtc2]

Get yourself the 850 bulbs, 85 CRI. The x65 bulbs have a blue tint to them.

This an 850 bulb (5000K). No flash, just the row against the wall was lit.

Billy T.
[email protected]

 

[sams]

I would use 4100K CRI 85 bulbs with the highest lumen output for wattage input you can find. Fluorescents maintain about 90% of their lumen output throughout their life.

While this is technically correct is isn't practically correct. Lumen measurements have a bias to warmer light and in my own experience I have found that the perceived light output from a 6500 lamp is significantly higher than the same 5000K lamp with the same lumen output.


Now the colour: 6500K despite some arguments is the closest to pure white. Some people have commented they look blue however this is due to them using warmer flourecents as a basis of reference. Anyone that does inspection work should have these. I do understand people not wanting these due to the harshness they are however the most practical.


Is there any way we can get this thread stickied as we seem to have this discussion over and over

 

[Sr. WiNdTeCh]

My life revolves around 6500k, every light in my house.

 

[rodm1]

4100 is grate.

 

[greatkids]

Absolutely. There have been studies of light color temps in offices that are windowless. People get headaches when things are all one temp. Wherever my wife worked, I always went in on the weekend and installed my own choice of lamps. I placed a small incandescent light on her desk with about a 60 watt and a shade. This variety is beneficial.

Of course, there is no substitute for natural light via windows or skylights. That is until you pull a night shift in an otherwise well lit (but improperly lit) work place.

Thanks for all the input. As each of the eight fixtures has four bulbs each, I think we'll start out with two 4100's and two 6500's (all with 85 CRI) in each fixture. Any reason not do do this?

We'll post an impression when the shop is finished.

Thanks again
Brian and kids
http://www.teamisetta.com/
http://www.teamsprite.com/

 

[gnxtc2]

Thanks for all the input. As each of the eight fixtures has four bulbs each, I think we'll start out with two 4100's and two 6500's (all with 85 CRI) in each fixture. Any reason not do do this?

We'll post an impression when the shop is finished.

Thanks again
Brian and kids
http://www.teamisetta.com/
http://www.teamsprite.com/

I would also pick up the 5000's ones also. I did the same as you.

Let us know what you decide on.

Billy T.
[email protected]

 

[Zengineer]

Thanks for all the input. As each of the eight fixtures has four bulbs each, I think we'll start out with two 4100's and two 6500's (all with 85 CRI) in each fixture. Any reason not do do this?

We'll post an impression when the shop is finished.

Thanks again
Brian and kids
http://www.teamisetta.com/
http://www.teamsprite.com/

The reason this isn't done often anymore (at least in larger buildings) is the need to inventory another SKU. For the home shop, this is a decent solution.

 

[greatkids]

"Thanks for all the input. As each of the eight fixtures has four bulbs each, I think we'll start out with two 4100's and two 6500's (all with 85 CRI) in each fixture. Any reason not do do this?

We'll post an impression when the shop is finished.

Thanks again
Brian and kids
http://www.teamisetta.com/
http://www.teamsprite.com/"

Sorry, each of the fixtures has six bulbs not four, so there will be three 4100's and three 6500's (or 5000's) in each fixture. Total of eight fixtures in a 720 sq.' shop with white walls and celling.

 

[Greatbear]

I prefer 4100K lamps in the workshop and garage. By "accident" I bought a box of 3000K lamps, and been using those in the house (washroom, etc). In the washroom I installed a pair of 3-lamp 34/40W troffers ages ago, these use two ballasts, one for a pair of lamps, and one for the single. The singles tend to fail sooner than the pairs do, and I put a 3k lamp in the fixture. When the light came on, I realized that I had gotten the "wrong" lamps. Since these were all I had, I left the new, "wrong" lamp installed until I could get out and get the proper replacements. As it turns out, the resulting light given off by this "hybrid" fixture (~3000k flanked by a pair of 4100K) is rather pleasing, and, given that this is the washroom with the washer/dryer and big double utility sink, it's easier to see the results of washing clothes and make out various colors (pairing off socks, that sort of thing is easier when the colors are only slightly different). Looking at the fixture itself appears odd at first (hey, there's an odd lamp in there, etc) but the light in that area is fuller and softer. I've kept that lamp combination strategy ever since.

 

[Aklass]

4100-500k is the color spectrum that gives out most visible to the human eye light, its a yellowish white, and 5000 k is a pure white 6500k I believe is a slightly bluish white

 

[sams]

4100-500k is the color spectrum that gives out most visible to the human eye light, its a yellowish white, and 5000 k is a pure white 6500k I believe is a slightly bluish white

that is incorrect, pure white is 6400 to 6500, although keep in mind many lighting companies show colour charts that are completely wrong. Although in my own experience the big industrial lighting companies seem to all be exactly right.

 

[Zengineer]

There is more light visible at 6500K than 5000K as well, all else being equal.

 

[GarageEnvy]

Definitely a personal preference but with my garage I used 5000k bulbs. As others mentioned I'd heard about them and went to a commercial lighting retailer where he had identical fixtures set up with different bulbs. That's where the difference is most noticable. When I mentioned it was for my shop, the guy said his wife was a welder (metal artist) and only works under 5000k bulbs.

 

[paris_tj]

I have 3200k and plan on buying 4100k soon. Current bulbs are too yellow....6500k are too expensive for me.

If you like the Daylight or 6500k ones, buy from a electric supply house. I just bought a case of the them for $1.99 each. That is about 33% of the price of HD or walmart around here. To me, that is pretty cheap.