We have a two circuit track light system in our kitchen that has 10 heads on two switches. Some kind of system that the switches work alternate heads.
Anyway, these are down pointing 120v heads, with big green shades. Ceiling height is 10′. The best looking bulbs are the white globe decorator bulbs. It seems to take 100w bulbs to yield enough light.
I have found a source for globe CFL bulbs, but the case quantity is 24, so the cost is not insignificant. More to the point, how can I figure out what color ‘temperature’ will work best? And will these CFL bulbs work well at all, given that they are pointed down?
Here is one example,
http://www.goodmart.com/products/409700.htm
On a related question, assuming we don’t do CFL, can anyone recommend a specific brand of globe bulbs? We got Sylvania, and found that the base was not very secure. They burned out quickly, and the globe broke away easily from the base. Maybe they aren’t designed for upside down use?
Replies
Flourescents don't *have* color temperatures. They're not blackbody sources. Whether you like them warm or cool is just a matter of taste. Look at them and take your pick.
We have base-up pendant fixtures in the kitchen, with large conical shades. These tend to retain heat, and we found that CFL's don't last as long as incandescents in those conditions.
-- J.S.
Here is a source of several styles of globes and capule bulbs.
These are 2700/2880k which matches incandenscents.
http://www.energyfederation.org/consumer/default.php/cPath/2050_25_44_168http://www.energyfederation.org/consumer/default.php/cPath/2050_25_44_168
http://www.energyfederation.org/consumer/default.php/cPath/2050_25_44_1619
And these are "daylight" or 5000k bulbs.
http://www.energyfederation.org/consumer/default.php/cPath/2050_25_44_668
True daylight varies by the time of the day, but 5000k is typical called daylight and I thing represents high noon. And 6500k is North Light daylight.
John is right in that the CFL's not truely hot body ratiators. But they have multiple clor spikes and the the color temp represents the peak light in that spectrum.
There is another parameter that indicates how well the light matches that of the ideal hot body radiator. CFL's are in the range of 82-84%.
While cheap cold white bulbs are as low as 65%.
I think that they can burn in any position, but check the specs. I have several of the "twisted style" (brand unknown) burning base up.
And I have a pair of the Pasonic tube shapped ones burning base up. They have provided very reliable and are in a semi-exposed outdoor area.
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I have Panasonic globe bulbs in cans in my ceiling, no problems. Been in there over a year with no failures.
Expensive yup, about $15 each.
Joe H
Fluorescent bulbs DO have a color-temperature rating, which is probably as valid for them as it is for incandescent bulbs (their little filaments don't burn at 6500 Kelvin, either!) Fluorescents get the different color spectrum by using different phosphors inside the tube (which fluoresce at slightly different colors.)
Although "daylight" sounds great, you probably will not like it in a kitchen as much as you would a "warm white".
There's a paradox in terminology here, which I'll try to explain as best _I_ understand it. Higher "color-temperature" bulbs look "colder" (or "cooler") to humans! This is because the higher c-t bulbs have more blue in them relative to the "warm white" bulbs, which are tailored to look more like the incandescent bulbs we are all used to seeing. The "warm white" bulbs have a color in which yellows and reds are more predominant, whch corresonds to a cooler radiating body (confused yet?? Just remember "Roy G. Biv" from your high school science classes; that's the acronym which lists the colors in "white" light (or the colors of the rainbow) in order of increasing energy.) And the old ugly "cool white" fluorescents looked that way because they had a LOT of blue in them! I'm not sure why we humans register "blue" as "cool"; it may have something to do with the filtering of the sun's light by the earth's atmosphere (which tends to filer out the bluer colors), and the lack of that filtering at higher altitudes (where it is colder.) But that IS how we're wired!
Anyway, enough theory. The "daylight" bulbs (which will have a color temperature of ~5000K (Kelvins) or greater) are GREAT for work spaces; the full color spectrum makes it easier to see fine details or read fine print. But most people don't like them for living spaces; they can make people's faces look sickly, and make food look weird.
ANOTHER thing to worry about: even so-called "instant-on" Compact Fluorescents can take 30 seconds or more to reach their full light output. Some brands are worse in this regard than others. This can pose a real problem in some areas. Bottom line: TRY BEFORE YOU BUY. If you can't return the bulbs you are buying by the case, you might just be buying a case of trouble!
G
So what level of CFL were you recommending for the K?
jt8
"One of the fondest expressions around is that we can't be the world's policeman. But guess who gets called when suddenly someone needs a cop." -- Colin Powell
Hi, John T8,
You had asked:
"So what level of CFL were you recommending for the K?" (K here being "Kitchen")
Unfortunately, when you start talking about "warm white", the K (Kelvin) numbers aren't so applicable! It's kinda like buying "mahogany" stain; you can buy three cans from three different manufacturers, paint them side-by-side on a piece of white pine, and all three will probably look somewhat (or a LOT) different from each other.
In very general terms, it would be a "lower" color temperature (I hate to say "cooler", because of the confusion in terminology noted earlier.) BillHartmann's post here indicated that 2700 to 2880K were considered to be equivalent to incandescents, and I wouldn't DISagree with that.
The trick here is that fluorescent bulbs "naturally" tend to look blue (i.e. higher color temperature.) It's only more recently that bulb manufacturers have developed phosphors that emit light more in the yellow, green and red ranges. So if a manufacturer is trying to duplicate the look of an incandescent bulb, he will create a mixture of phosphors with predominantly yellow output, plus some reds, greens and blues so that the bulb doesn't end up looking like a Bug-Lite!! Obviously, when mixing colors like this, there are a lot of ways the final color output can vary; and it's my understanding that many mixed-phosphor bulbs (of which "warm white" is one) have an ultimate spectrum which does not resemble ANY "hot-body radiator". Therefore, the concept of such a bulb being rated with a color temperature is almost irrelevant.
I used to have some bookmarks that explained the color-temperature thing in great detail, but darned if I can find them at the moment. I do have one guy's website who reviews many brands of bulbs semi-regularly, both for color and quality:
http://members.misty.com/don/cfbest.html
He may have some comments on bulbs you're looking at, or that you can find in your area.
My recommendation: the CFLs really can save a lot of energy; and in California, they are now mandated in many locations within a house. Pick out several CFLs that are candidates, get yourself a good "soft-white" incandescent of similar light output, and do a "taste test". It will be easier if you obtain a few of those cheap clamp-lights with reflectors, and use them for your test fixtures, so that you can switch between bulbs rapidly. (In my experience, women are usually better at detecting color differences in this sort of setup. In general, their brains seem to be better wired for color; and they usually are pretty aware of how makeup colors and food colors are supposed to look. Nothing sexist intended here, ladies; just my observations, and I KNOW it holds true for me!!)
It probably sounds like a lot of work, but it will pay off big-time in the end result; and hopefully, you won't have to do it again until (a) the bulbs burn out (which could be years) and (b) the manufacturer stops making the bulb you selected! You might even be able to save some others a bunch of effort by posting your test results here!!
George
> (their little filaments don't burn at 6500 Kelvin, either!)
True, the practical maximum for tungsten filaments is about 3350 - 3400 K. That's for old fashioned photofloods, the ones rated for a life of only 4 - 6 hours. The actual temperature of a filament is off from the CT by something like 50 K, I forget whether its higher or lower.
As for blue being hotter, you can sort of get that from watching a blacksmith work. When the metal gets barely hot enough to glow, it's dull red. Heat it higher, and it goes towards orange and yellow. Of course, it melts before you can get through the whites to blue. Whites are where most of the blackbody curve falls in the 400 - 700 nm visible spectrum. Heat things even more, and it shifts out the other end, where blue is.
You can also sort of see it from the blackbody locus on the 1931 CIE chromaticity chart, but they usually only show the middle where the reasonable white point choices are.
Color temps for flourescents are even more bogus than shop vac horsepower. The shop vacs only give you an incorrect numerical value, they're still talking about power. Flourescents are nowhere close to having blackbody spectral distributions, like the sun and incandescents. They can only claim that it sorta looks like a particular CT to some folks.
-- J.S.
:-)
You said it better than I did, J.S.!
Also, what we hoomans perceive as "white" actually comes from a mixture of ALL the colors. The white associated with REALLY hot bodies is, I believe, representative of a plasma state (i.e. no "elements", just protons and neutrons and electrons in a soup), wherein all possible color wavelengths are equally represented statistically.
Yeesh, didja ever think you'd find so much physics on a HOMEBUILDING site???
:-),
G
"...so much physics on a homebuilding site..."
This is why I love BT - learn something new every day!
physics is nice, but I just wanted to know which bulbs to use where :)
jt8
"One of the fondest expressions around is that we can't be the world's policeman. But guess who gets called when suddenly someone needs a cop." -- Colin Powell
I used incandescents that were mirrored on the inside for downlights in an previous home
..they would kick the light back into the reflector.and you could look at them while they were running because of the mirror
mine were from Westinghouse..but I don't use those fixtures anymore ,so I don't know if they are still made...
but they looked like this....
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, wer ist jetzt der Idiot ?
I have not seen them in years.But I see that the reflector bulbs are available in CFL's.They are in the links I posted above..
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A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
I see those now , I just don't get warm fuzzies from fluorescents...I also see a cold cathode lamp !
have to find out if those can withstand some vibration from a screen door banging shut.....
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., wer ist jetzt der Idiot ?
Bryan,
It really is a matter of personal preference in terms of what color temperature to use, and you might like different bulbs in different rooms (with different paint, light levels).
But you probably can get the same type of bulb from the same manufacturer in a more standard (and thus cheaper and available in one piece quantities). Get one or two of each color temperature you think you might like and try them, without investing in a whole case. Use the extras somewhere that is not as important.
Hilltop