# What's your preferred color temp for CFLs?



## Lightmeup (Feb 23, 2006)

I've seen a lot talk lately about how much more people prefer the "daylight/full spectrum" etc. CFLs to the more common 2700 degree variety. I have a few of these 2700 degree bulbs and also find them to be yellow and dim with poor color rendition. I want to replace my incandescents with CFLs, but not the 2700 degree variety. The problem is that the terms like "daylight and full spectrum" seem kind of meaningless. Bulbs with these descriptions can have a wide variation in color temp. I have looked around and bulbs seem to be generally available in 3500, 4100, 5000, and 6500 degree versions. 

I have two general requirements. A lot of small output bulbs for ceiling fixtures that take 5 or 6 bulbs. I'm thinking 9-13W would be fine. Anything bigger would be too bright. And then some larger 20-25W bulbs for lamps or other single bulb applications that would need more brightness.

I guess I'm thinking probably the 4100 or 5000 degree versions would be my best choice. But I was wondering if you folks who have tried these out already would chime in with your favorite color temp (degrees) preference? Also, do you find that different temps are more appropriate for certain applications, like background lighting, reading, watching TV, or whatever?

LMU


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## NewBie (Feb 23, 2006)

Personally, I like 6500k, but many of the CFL bulbs out there have poor phosphor choices, which really limits the CRI. As such, many 6500K CFLs don't look all that great.

Though, as things are winding down at the very end of the day, I really prefer the warmer color temps, very late in the evening. But if I am working, I like the 6500K temp in the late evening.

It is interesting how my color preferences follow a day sun cycle.

That said, I don't mind 9300K color temps either, when I am working. Overcast days can reach 10000K color temp.

Remember, CRI and color temp don't necessarily fall hand in hand.

It will be nice when we can hit the local store and buy LED bulbs with adjustable color temperatures.


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## jtr1962 (Feb 23, 2006)

5000K but anything from 4100K to 6500K is just fine provided the CRI is decent (mid 80s or better). Note that it's more I tolerate CRI in the mid 80s but prefer it in the 90s.


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## brickbat (Feb 24, 2006)

NewBie said:


> Though, as things are winding down at the very end of the day, I really prefer the warmer color temps, very late in the evening.



I'm the same way. If I'm supplementing natural daylight, higher color temps are good, and lower color temps seem too yellow. But after sundown, I find high color temps too jarring most of the time. No way would I use 4100K lamps for general background/TV watching, etc. I do perceive 2700/3000 K lamps as generally somewhat yellowish, but don't find that objectionable.

But that's me. It's really a matter of individual choice. Try some, and let us know what works for you. If being used as general background lighting in a residence, I believe the optimum color temp depends on the colors in the room environment. Got blue carpet? 2700K lamps aren't gonna make it look very vibrant.

I've found that not all 2700 and 3000K lamps look the same. Most seem to have a pinkish tint. Going to the higher color temps is one way to get away from that, if it bugs you.


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## asdalton (Feb 24, 2006)

That's pretty much the same for me. I prefer the warm-white tints for living spaces, and the cooler tints for kitchens, bathrooms, and work spaces.


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## jtr1962 (Feb 24, 2006)

One big problem with almost all the CFLs commonly sold in retail stores is that the CRI isn't particularly good. Usually it's in the 80 to 82 range, which is passable for general lighting but won't bring out all the colors. Usually it's the deep reds which are lost, and this is regardless of color temperature. Lower color temperatures such as 3000K are simply achieved by altering the ratio of red to green and blue phosphors, but the red phosphor still doesn't emit in the deep red. As a result with the low color temperature lamps your brain tells you the deep red should be there due to the apparent color temperature of the light but it isn't. For that reason I consider low-color temp CFLs the worst possible choice regardless of decor. Not only does the light color inherently distort colors same as incandescent, but it's missing crucial parts of the spectrum which happen to be large chunks of a typical incandescent spectrum. The lack of deep reds with higher color temperature CFLs isn't as apparent since your brain doesn't expect as much of them. For that reason alone if all you have available are CFLs with so-so CRI I'd recommend going with the higher color temperature ones. If you really find high-color temperatures like 6500K objectionable then 3500K is still fairly soft, but without the annoying yellow cast of the 2700K/3000K lamps.

Regarding decor, I've noticed modern decor tends to have more neutral/cold colors. These will definitely look better under high CCT CFLs and look absolutely horrid under the soft white ones (whites in particular are disgusting under soft-white light). The only colors soft white CFLs might cause to look better are decors heavy in wood tones and reds (but not deep reds). However, this is relative only to higher color temp CFLs with the same 80 to 82 CRI. A decent (CRI 90+) 5000K CFL will cause wood to look just as rich as it does under any kind of light, and it will bring out some of those deep reds that normal CFLs don't.

All this being said, I really feel CFLs are only a quick and dirty solution to save energy. The selection of color temperatures is very limited, usually being between 2700K and 6500K in most stores. The selection of ones with decent phosphors is even more limited, with nothing above about 84 easily available in any color temperature other than 5000K. Long term I feel every household is better served converting to electroncially-ballased fixtures using four foot T8 lamps. Even at Home Depot you have a pretty good selection of lamps. Via mail order you can get any color temp you want with a CRI of at least 86, and some (3000K and 5000K) are available with CRI up to about 93. There are even a few ~5500K ones with a CRI of 98 available which are quite close to sunlight. Besides all this, the linear T8s are 50% more efficient than CFLs, and the tubes last 20,000 to 35,000 hours instead of the 6,000 to 10,000 of CFLs.


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## Lightmeup (Feb 24, 2006)

brickbat said:


> But after sundown, I find high color temps too jarring most of the time. No way would I use 4100K lamps for general background/TV watching, etc.


So this has nothing to do with brightness though, right? You would prefer a 13W 2700K bulb to a 9W 4100K bulb?


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## jtr1962 (Feb 24, 2006)

Lightmeup said:


> So this has nothing to do with brightness though, right? You would prefer a 13W 2700K bulb to a 9W 4100K bulb?


In general high-color temperature lights look better when your overall lighting level is higher. I've heard some people here complain that a single 23 watt 6500K CFL can make a room look "gloomy" but when they put 3 in the same room it looks just fine. However, even for low lighting levels I'd recommend not going with anything warmer than 3500K. 3500K will still look fine in a dimly lit room without having the obnoxious yellow overtones of the more common 2700K/3000K. In fact, it seems in LED circles 3500K is being standardized upon as the new "warm white". That being said, I personally don't find 5000K or 6500K objectionable even at low lighting levels. It reminds me of being outside on a moonlit night.


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## brickbat (Feb 24, 2006)

Lightmeup said:


> So this has nothing to do with brightness though, right? You would prefer a 13W 2700K bulb to a 9W 4100K bulb?



Well, yes, I'd prefer the lower color temp without regard to the brightness for background/general lighting. With task lighting, I'm less picky. But so what? 

My favorite vegetable is swiss chard, but I'm not gonna call the other choices horrid, annoying, or obnoxious. To each, his own.

Find out what you like and go with it. And if you happen to share your abode with a wife/parents/kids, you may find they don't see things in the same light as you. So in the public spaces, you'll have to compromise.

BTW, haven't we all been here before, last October...


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## jtr1962 (Feb 24, 2006)

brickbat said:


> My favorite vegetable is swiss chard, but I'm not gonna call the other choices horrid, annoying, or obnoxious. To each, his own.


Just to be fair, I use the same adjectives for excessively blue light as well. :nana: As for compromise, 3500K is definitely for anyone in a situation where the people see things differently. It's not cool enough for those who like incandescent like lighting to find it objectionable, yet it's not warm enough that those who like cool lighting will complain, either.

I'm of the opinion though if kids are involved go with 5000K, high CRI lighting regardless of you or your wife/husband's personal preferences. My reason? Because long term anything other than light close to sunlight can cause eyestrain which in turn can lead to other vision problems. And in addition to that I recommend lighting a place brightly (100 lumens/ft² minimum) when kids are involved for similar reasons, especially when they're doing close work.


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## flashfan (Feb 25, 2006)

As a general rule, I like lights of 4200K or higher throughout the house...except for the living/family room, and dining room chandelier. I once tried a 55-watt CFL (5500 or 6500K) bulb in a living room torchiere lamp, and it was horrible. The room looked "odd" and just felt really unpleasant/depressing. Changed it back to a lower temperature color, and we're happy campers.

And like my flashlight preference, I want/need my lights to be as bright as possible. Used to use a bunch of 300-watt torchiere lamps, now "downgraded" to 55, 85 and 105 watt CFLs. The only downside is these bulbs are extreemely expensive and HUGE! Also, I don't think the life of the bulbs is anywhere near the stated runtimes--better than incandescent, but for the price...


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## James S (Feb 25, 2006)

lowes carries phillips bulbs at 4100k here and I think they are great. As my old horrible 2700k Commercial Electric bulbs from HD die I'm replacing them with these. The color is very white, without being blue and they are locally available and not too expensive.

Since these things are a bit of an investment to do the whole house. I recommend you pick up one of each of those listed settings. YOu can order off the web if you need to get one of each. It will be easy to see which is better in your own eyes.


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## jtr1962 (Feb 25, 2006)

flashfan said:


> I once tried a 55-watt CFL (5500 or 6500K) bulb in a living room torchiere lamp, and it was horrible. The room looked "odd" and just felt really unpleasant/depressing.


Well, going from 2700K to 5500K/6500K _is_ a huge jump, and undoubtedly decor affects color temp choices. We still have incandescents in the three chandeliers here (despite my and my mom's hatred of the light color), but we hardly use them. I'm really waiting for LED small-base replacement bulbs for these since current CFL replacements are too expensive/not dimmable. At the rate power LEDs are falling in price and increasing in efficiency I might try my hand at just making the LED bulbs myself once I can get 100 lm/W, 3 watt or so LEDs. 2 of them would handily replace a 60-watt small-base bulb.


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## Lightmeup (Feb 26, 2006)

The reason I ask is that I recently ran across this deal on ebay:
http://cgi.ebay.com/50-COMPACT-FLUO...ryZ20706QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

15W, 5000k, 550 lumen bulbs for about $1.30 apiece. I need a lot if I'm going to change everything out, and this seemed like a good deal. The CRI is only 82 though. Anyone know anything about these bulbs?


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## NewBie (Feb 26, 2006)

jtr1962 said:


> One big problem with almost all the CFLs commonly sold in retail stores is that the CRI isn't particularly good. Usually it's in the 80 to 82 range, which is passable for general lighting but won't bring out all the colors. Usually it's the deep reds which are lost, and this is regardless of color temperature. Lower color temperatures such as 3000K are simply achieved by altering the ratio of red to green and blue phosphors, but the red phosphor still doesn't emit in the deep red. As a result with the low color temperature lamps your brain tells you the deep red should be there due to the apparent color temperature of the light but it isn't. For that reason I consider low-color temp CFLs the worst possible choice regardless of decor. Not only does the light color inherently distort colors same as incandescent, but it's missing crucial parts of the spectrum which happen to be large chunks of a typical incandescent spectrum. The lack of deep reds with higher color temperature CFLs isn't as apparent since your brain doesn't expect as much of them. For that reason alone if all you have available are CFLs with so-so CRI I'd recommend going with the higher color temperature ones. If you really find high-color temperatures like 6500K objectionable then 3500K is still fairly soft, but without the annoying yellow cast of the 2700K/3000K lamps.
> 
> Regarding decor, I've noticed modern decor tends to have more neutral/cold colors. These will definitely look better under high CCT CFLs and look absolutely horrid under the soft white ones (whites in particular are disgusting under soft-white light). The only colors soft white CFLs might cause to look better are decors heavy in wood tones and reds (but not deep reds). However, this is relative only to higher color temp CFLs with the same 80 to 82 CRI. A decent (CRI 90+) 5000K CFL will cause wood to look just as rich as it does under any kind of light, and it will bring out some of those deep reds that normal CFLs don't.
> 
> All this being said, I really feel CFLs are only a quick and dirty solution to save energy. The selection of color temperatures is very limited, usually being between 2700K and 6500K in most stores. The selection of ones with decent phosphors is even more limited, with nothing above about 84 easily available in any color temperature other than 5000K. Long term I feel every household is better served converting to electroncially-ballased fixtures using four foot T8 lamps. Even at Home Depot you have a pretty good selection of lamps. Via mail order you can get any color temp you want with a CRI of at least 86, and some (3000K and 5000K) are available with CRI up to about 93. There are even a few ~5500K ones with a CRI of 98 available which are quite close to sunlight. Besides all this, the linear T8s are 50% more efficient than CFLs, and the tubes last 20,000 to 35,000 hours instead of the 6,000 to 10,000 of CFLs.




When going with T8 and other linear fluorescents, it also pays to do your research on ballasts, as you can get ballasts that are only 70% efficient as well as 93% efficient. Thats a whopping 23% difference in efficiency.


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## brickbat (Feb 26, 2006)

Your original post led me to believe that you hadn't tried any high color temp lamps in your house, and didn't know what color temp to pick. Now you want to buy 50 of 'em ??? Going from 2700 to 5000 is still a pretty big jump. 

As to the specific lamps on eBay, I've never heard of the Energetic brand, and would be a bit suspicious of its reliability. Can't see the markings on the lamp to check for UL listing, but I would check that, before filling my house with these.


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## brickbat (Feb 26, 2006)

jtr1962 said:


> Because long term anything other than light close to sunlight can cause eyestrain which in turn can lead to other vision problems.



That sounds like something straight out of a marketing brochure for a Full Spectrum lamp...


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## jtr1962 (Feb 26, 2006)

brickbat said:


> That sounds like something straight out of a marketing brochure for a Full Spectrum lamp...


I remember reading studies to that effect some years ago, and definitely not in a marketing brochure for full spectrum lamps. I also add in my own experiences. I never liked doing any close work under incandescents because the yellow color gave me headaches and the light levels were too dim. Old school cool-white fluorescents were better, but I always felt something was lacking. Years later I learned about flicker and color rendering. I tried some high CRI, 5000K tubes in the shoplights in my workroom downstairs and also changed out the magnetic ballasts for electronic ones. It was way better than the old cool-white lamps in terms of eyestrain and ability to work long periods without fatigue. My own results matched those in the study, and that's what I base my recommendations on.



Newbie said:


> When going with T8 and other linear fluorescents, it also pays to do your research on ballasts, as you can get ballasts that are only 70% efficient as well as 93% efficient. Thats a whopping 23% difference in efficiency.


Typical overall system efficiency for T8 tubes and ballasts is 82 lm/W. Don't forget that driving a tube at the 25 to 50 KHz frequencies of most electronic ballasts results in an efficiency increase of 10 to 15% over whatever the tube is rated at since T8 tubes are rated on 60 Hz magnetic ballasts. This sometimes covers all the losses in the electronic ballast. I've seen many T8 ballasts which drive the tubes at a ballast factor of 0.89 while using about 28 to 30 watts per tube. This equates to an overall system efficiency of 95 to 102% of the tube itself. In my kitchen the ballast drives 4 tubes to 89% of brightness while using 107 watts. The tubes are rated at 2950 lumens at 32 watts _on a magnetic ballast_, or 92 lm/W. With the mentioned ballast the overall system efficiency 4x0.89x2950/107 = 98 lm/W, or more than the tubes by themselves! The ballast is instant start. In general instant start ballasts are more efficient although a little harder on the lamps. With rapid start ballasts system efficiencies roughly equal to the lamps themselves are more typical. 32 watt T8 lamps generally are rated at anywhere from 2750 to 3300 lumens, so the choice of lamp can make up to a 20% difference in overall efficiency. As a general rule go with the slightly more expensive SPX over the SP phosphors if using commodity tubes since they give about 2900 lumens instead of 2750, and have better color rendering (86 versus 78).


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## jtr1962 (Feb 26, 2006)

Lightmeup said:


> The reason I ask is that I recently ran across this deal on ebay:
> http://cgi.ebay.com/50-COMPACT-FLUORESCENT-MINI-SCREW-IN-BULBS_W0QQitemZ4442983137QQcategoryZ20706QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
> 
> 15W, 5000k, 550 lumen bulbs for about $1.30 apiece. I need a lot if I'm going to change everything out, and this seemed like a good deal. The CRI is only 82 though. Anyone know anything about these bulbs?


I don't know anything about those particular lamps but as brickbat said check with the seller if they are UL rated. You don't want something which could potentially start a fire in your house. As for the CRI of 82, it will be less noticeable on a high-color temp lamp for the reasons I mentioned earlier, and will be just fine for most casual lighting. The main thing lacking will be deep reds but that will be the case with most of the CFLs sold except the full-spectrum ones regardless of color temp. If they are decent lamps it's a great deal though. If you want full-spectrum high CRI 5000K lamps try these although they are somewhat pricey compared to most other CFLs.

As for the jump from 2700K to 5000K, either you'll like it and quickly get used to it or you won't. If you don't this doesn't necessarily mean that higher color temp lamps aren't for you, but rather that 3500K might be a better place to start. I'm guessing already that since you mentioned that the 2700K lamps are dim and yellow to you you'll probably make the adjustment. The only question is will you prefer 3500K, 4100K, 5000K, or 6500K? Only you can answer that question. You might want to pick up one of the Commercial Electric 23 watt, 6500K lamps which Home Depot sells to either confirm or eliminate 6500K as a potential choice. It'll also give you some idea of whether you'll prefer something a little less blue (i.e. 5000K), or maybe intermediate between 6500K and 2700K (i.e. 4100K), or something closer to 2700K but still somewhat whiter (i.e. 3500K). Or perhaps you'll prefer different color temps in different rooms as some people here use.


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## Lightmeup (Feb 26, 2006)

Wow jtr1962, those bulbs you mentioned are a lot more expensive. $12-$14 apiece, IF you buy a dozen. That ebay seller I mentioned also has some 13 watt mini in 6500k as well as 24 watt in 5000k for the same price. I think I'll order a few of each to experiment with before I buy any larger quantities. This is the best deal I've seen for higher temp bulbs. The 2700K variety could always be had for under $2, but until recently the higher temps were always much more expensive. I don't have any deep reds in the home to speak of, so I don't think I'll feel deprived by the CRI=82. It should be a big improvement over the incandescents. What's the typical color temp and CRI of an incandescent? 

LMU


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## jtr1962 (Feb 26, 2006)

Lightmeup said:


> What's the typical color temp and CRI of an incandescent?


It can be as low as 2500K for 25 watt, small base candelabra type bulbs but figure about 2800K for a 60 watt bulb and 2900K for a 100 watt bulb. CRI is by definition 100 since an incandescent bulb is a blackbody but of course its really the combination of CRI and color temp which makes a light source feel "natural".

Keep us updated on how you find the various color temps compared to standard 2700K.

Yes, those full-spectrum CFLs are pretty pricey which is why I never bought any. I do use their 32W T8 tubes though and I'm quite satisfied.


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## NewBie (Feb 27, 2006)

Newbie said:


> When going with T8 and other linear fluorescents, it also pays to do your research on ballasts, as you can get ballasts that are only 70% efficient as well as 93% efficient. Thats a whopping 23% difference in efficiency.





jtr1962 said:


> Typical overall system efficiency for T8 tubes and ballasts is 82 lm/W. Don't forget that driving a tube at the 25 to 50 KHz frequencies of most electronic ballasts results in an efficiency increase of 10 to 15% over whatever the tube is rated at since T8 tubes are rated on 60 Hz magnetic ballasts. This sometimes covers all the losses in the electronic ballast. I've seen many T8 ballasts which drive the tubes at a ballast factor of 0.89 while using about 28 to 30 watts per tube. This equates to an overall system efficiency of 95 to 102% of the tube itself. In my kitchen the ballast drives 4 tubes to 89% of brightness while using 107 watts. The tubes are rated at 2950 lumens at 32 watts _on a magnetic ballast_, or 92 lm/W. With the mentioned ballast the overall system efficiency 4x0.89x2950/107 = 98 lm/W, or more than the tubes by themselves! The ballast is instant start. In general instant start ballasts are more efficient although a little harder on the lamps. With rapid start ballasts system efficiencies roughly equal to the lamps themselves are more typical. 32 watt T8 lamps generally are rated at anywhere from 2750 to 3300 lumens, so the choice of lamp can make up to a 20% difference in overall efficiency. As a general rule go with the slightly more expensive SPX over the SP phosphors if using commodity tubes since they give about 2900 lumens instead of 2750, and have better color rendering (86 versus 78).




Ballast Catalog:
http://www.gelighting.com/na/busine...e_library/ballast/downloads/89458_ballast.pdf


A cross-section of High End bulbs, info provided by GE:

F32T8/SP65/ECO 
Watts 32 
Lumens (Initial) 2700 
Lumens (Mean) 2565 
Average Rated Life 20000 
Color Temperature (K) 6500 
Color Rendering Index (Ra) CRI 78
Nominal Efficacy (Lumens/Watt) 82


F32T8/SPX50/ECO 
Watts 32 
Lumens (Initial) 2800 
Lumens (Mean) 2660 
Average Rated Life 20000 
Color Temperature (K) 5000 
Color Rendering Index (Ra) CRI 86 
Nominal Efficacy (Lumens/Watt) 85 

F32T8XLSPX30HLEC 
Watts 32 
Lumens (Initial) 3100 
Lumens (Mean) 2915 
Average Rated Life 24000 
Color Temperature (K) 3000 
Color Rendering Index (Ra) CRI 85 
Nominal Efficacy (Lumens/Watt) 94


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## brickbat (Feb 27, 2006)

jtr1962 said:


> ...check with the seller if they are UL rated ...



Of course the good thing about non-UL listed lamps is that you'll get plenty of deep red, orange, and yellow when your house burns. And many burning homes make an almost-perfect blackbody radiator, so the CRI will be quite good, although the low color temperature (and smoke, for that matter) may cause eyestrain...


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## Lightmeup (Feb 28, 2006)

I checked, and they are UL listed.


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## jtr1962 (Feb 28, 2006)

brickbat said:


> Of course the good thing about non-UL listed lamps is that you'll get plenty of deep red, orange, and yellow when your house burns. And many burning homes make an almost-perfect blackbody radiator, so the CRI will be quite good, although the low color temperature (and smoke, for that matter) may cause eyestrain...


:laughing:


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## Lightmeup (Mar 6, 2006)

Does anyone know if there would be any problem using a regular CFL in a lamp with a 3-way brightness switch? (Not a dimmer, but the rotary switched socket that uses the 3-way incandescent bulbs). I know that it won't give different brightness levels, but I just want it to operate in a regular all/on or all/off mode.


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## jtr1962 (Mar 6, 2006)

Lightmeup said:


> Does anyone know if there would be any problem using a regular CFL in a lamp with a 3-way brightness switch? (Not a dimmer, but the rotary switched socket that uses the 3-way incandescent bulbs). I know that it won't give different brightness levels, but I just want it to operate in a regular all/on or all/off mode.


No problems at all. Just be aware that the CFL will only operate in the medium and high switch positions, not the low one, and as you said not at different brightness levels.

I remember looking for 3-way CFLs last year to replace the 3-way 2700K ones we have in a few table lamps but really couldn't find any in color temps other than 2700K.


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## Lightmeup (Mar 6, 2006)

So when I turn it on or off, it doesn't matter what position the switch is on; off/low is off, and medium/high is on?


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## jtr1962 (Mar 6, 2006)

Lightmeup said:


> So when I turn it on or off, it doesn't matter what position the switch is on; off/low is off, and medium/high is on?


Yes, that's the way it works. Basically two clicks on, next two clicks off, etc. The base center of regular 3-way bulbs is the higher-wattage filament, the ring outside that is the lower-wattage filament, and the screw part is connected to both filaments. Off means no power all all, low is power to the outer ring, medium is power to the base center, and high is power to the base center and outer ring. A regular CFL will of course only work with power to the base center, and this is the medium and high positions.


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## Lightmeup (Mar 6, 2006)

One thing I'm wondering about is the brightness (lumens) ratings for some of these bulbs. The ones I mentioned above were 15W, 5000K temp, 550 lumens output. There are also 14W, 2700K temp, 900 lumens output, and 11W, 2700K temp, 550 lumens output available for about the same price. Why do the higher color temp bulbs seem less efficient?


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## chevrofreak (Mar 6, 2006)

I got a 3 pack of the 5500K fluoro's from Home Depot, and while they work great for photography I find them to be too blue. While at Lowes the other day I noticed a 3500K "daylight" type fluoro spiral, I might get one to try.


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