CRI and lamp life

stevebea

Senior Member
I know CRI and lamp life are directly related. A lamp with a CRI of 80 will have app. half the lamp life of a lamp with a CRI of 52. Does this have to do with the phosphors in a flourscent lamp? Enlighten me. :)
 

Electric-Light

Senior Member
I know CRI and lamp life are directly related. A lamp with a CRI of 80 will have app. half the lamp life of a lamp with a CRI of 52. Does this have to do with the phosphors in a flourscent lamp? Enlighten me. :)
You got that completely wrong. Basic T8 lamps were rated at 20,000 hours with CRIs in mid 70s. The tightening energy standards are making them obsolete. Modern T8 lamps have CRIs from 80 to 86, output of 2900 to 3100 for a 32W and a life rating of 26,000 to 50,000 hrs.

You can get F15T8, F30T8 and such with traditional warm white phosphor (CRI 53) , but they're not installed for general lighting and they tend to have a life of 5000 to 9000 hours with glow starter bottle start.
 

broadgage

Senior Member
Here in the UK, the better color rendering lamps are more expensive and usually a little less efficient, but they have the same life time.
T8 lamps are normally more efficient and longer lasting than T12 which are obsolete for general lighting.
When T8 lamps first came on the market, only the popular colours were available, 827, 830, 840, and 865. Therefore "colour matching" and other specialist colours initialy had to be in the older and shorter lived T12 formatt.
These days the high color rendering lamps are available in T8 and are stated to have the same lifetime as the lower color rendering lamps.
 

stevebea

Senior Member
You got that completely wrong. Basic T8 lamps were rated at 20,000 hours with CRIs in mid 70s. The tightening energy standards are making them obsolete. Modern T8 lamps have CRIs from 80 to 86, output of 2900 to 3100 for a 32W and a life rating of 26,000 to 50,000 hrs.

You can get F15T8, F30T8 and such with traditional warm white phosphor (CRI 53) , but they're not installed for general lighting and they tend to have a life of 5000 to 9000 hours with glow starter bottle start.
This week I lamped a 2 lamp circleline T9 fixture. To make a long story short both lamps were 3000k but the 32w had a CRI of 52 while the 40w had a CRI of 80. The 40w was rated at 8000 hrs. while the 32w was rated at 12,000 hrs. Even though they were both 3000k the color difference was very different. Turns out supply house sent the wrong 32w lamp but it got me thinking about CRI and lamp life being related.
 

Electric-Light

Senior Member
Here in the UK, the better color rendering lamps are more expensive and usually a little less efficient, but they have the same life time.
T8 lamps are normally more efficient and longer lasting than T12 which are obsolete for general lighting.
When T8 lamps first came on the market, only the popular colours were available, 827, 830, 840, and 865. Therefore "colour matching" and other specialist colours initialy had to be in the older and shorter lived T12 formatt.
These days the high color rendering lamps are available in T8 and are stated to have the same lifetime as the lower color rendering lamps.
RE80s are more efficacious than RE70s getting close to 100 lm/W. RE70 phosphors are on their way to retirement.

We do have wide spectrum RE90s (yielding CRI ratings of 90 to 98), but they are not efficacious with efficacy of 50-60lm/W at best. These provide good color rendering, but also poor efficacy as they emit in a wider band including areas of spectrum where our eyes are not particularly sensitive.

RE80s use a blend of three phosphors hence the name "triphosphor" or "trichromatic" only emitting only in three narrow bands thus improving efficacy.
 

Electric-Light

Senior Member
It is the rare-earth phosphor blend RE80s that are seeing the most development right now.

90+ CRI lamps have been around for decades and they exist, but they only put out about 2/3 the light output for given energy use. In my opinion, they have no use in general lighting.

There was a company called Duro-Test (the name exists, but the original company is gone) that tried to push high CRI lamps for general service lighting from retail shops to classrooms with strong marketing effort using questionable claims of benefits to push "full spectrum" lamps.

They claimed things like "more natural", better for health, ability to see better, positive effect on learning and so on with their ~5500K 90+ CRI lamps. I guess there was a time when you'd see them for general lighting. The lumen output sucked no matter what and now, you don't see these extremely inefficient lighting except in very special applications like color proofing, dental labs, museum exhibits and auto body shops.
 

birtclp

Member
It is the rare-earth phosphor blend RE80s that are seeing the most development right now.

90+ CRI lamps have been around for decades and they exist, but they only put out about 2/3 the light output for given energy use. In my opinion, they have no use in general lighting.

There was a company called Duro-Test (the name exists, but the original company is gone) that tried to push high CRI lamps for general service lighting from retail shops to classrooms with strong marketing effort using questionable claims of benefits to push "full spectrum" lamps.

They claimed things like "more natural", better for health, ability to see better, positive effect on learning and so on with their ~5500K 90+ CRI lamps. I guess there was a time when you'd see them for general lighting. The lumen output sucked no matter what and now, you don't see these extremely inefficient lighting except in very special applications like color proofing, dental labs, museum exhibits and auto body shops.
I remember those guys calling on us in the 90s. Now there are a lot of LED mfrs using the same tactics and making the same smoke-and-mirror type claims. Same song and dance, different product.

Philips standard T8 lamp at 78 CRI touts 2800 lumen output and 30,000 hour lamp life @ 12 hours on.

Philips standard T8 lamp at 85 CRI touts 2950 lumen output and 30,000 hour lamp life @ 12 hours on.

No difference in lamp life, but better CRI and lumen output. Higher CRI lamp does cost more. Philips offers a higher lumen output (3100 lm) lamp, but it is only available in the higher CRI. They also offer a longer life lamp (36,000 hours @ 12 hours on) but there is no difference in lamp life between 78 CRI and 85 CRI versions.

I believe Sylvania and GE T8 lamp offereings are similar to Philips.
 

Electric-Light

Senior Member
Philips standard T8 lamp at 78 CRI touts 2800 lumen output and 30,000 hour lamp life @ 12 hours on.

Higher CRI lamp does cost more.

I believe Sylvania and GE T8 lamp offereings are similar to Philips.
The 85 CRI will become the standard in my opinion, unless they can/choose to tweak the RE70s to meet the new legislation.

Manufacturing of lamps not meeting these standards is banned July 2012. I don't know if they'll continue producing at full production until the deadline or if they'll voluntarily halt it sooner.

For what the average specifiers need to know about 4' T8 lamps, 89 lpw is required for all but daylight. 5000 and 6500K requires 88 lpw.

2850 lm required for 32W
2816 lm required for 32W in 5,000 and 6,500K

Current RE 70 lamps rated at 2800 lumens will not meet the standards, but by an amount I considered to be negligible in real life.

I'll set aside the 90+ CRI products, as they're not used for general purpose lighting.

Almost all CFLs and T5s use RE80 now. Base T8s use RE70 and upgraded ones use RE80 as of now.

The lamps that do meet the energy code have a minimum efficacy of 89 lpw and best ones have 97 lpw and they only lose measly 5% output from new to burn out, excluding loss caused by lamps/fixtures getting dirty or diffuser yellowing. Not bad seeing that LEDs are allowed 30% loss during "lifetime".
 
Last edited:

BullsnPyrs

Senior Member
This week I lamped a 2 lamp circleline T9 fixture. To make a long story short both lamps were 3000k but the 32w had a CRI of 52 while the 40w had a CRI of 80. The 40w was rated at 8000 hrs. while the 32w was rated at 12,000 hrs. Even though they were both 3000k the color difference was very different. Turns out supply house sent the wrong 32w lamp but it got me thinking about CRI and lamp life being related.
Why do you focus on the CRI? You are comparing lamps of two different wattages.
 

Electric-Light

Senior Member
This week I lamped a 2 lamp circleline T9 fixture. To make a long story short both lamps were 3000k but the 32w had a CRI of 52 while the 40w had a CRI of 80. The 40w was rated at 8000 hrs. while the 32w was rated at 12,000 hrs. Even though they were both 3000k the color difference was very different. Turns out supply house sent the wrong 32w lamp but it got me thinking about CRI and lamp life being related.
3000K CRI 52 is the classic warm white phosphor. Been around for over half a century. The 80 CRI is RE80.

Neither GE nor Philips makes 40W in 3000K. They both make 32W in RE830 and 40W in classic cool white (62 CRI)
Neither makes any Circline in 3000K/WW.

http://www.usa.lighting.philips.com/pwc_li/us_en/connect/tools_literature/downloads/SAG-100_2009_Fluorescent.pdf

GE and Philips are all 12,000 hours.

What's the brand, model and date code? The same brand/model from 1995 won't necessarily have the same specs as 2009.
 

weressl

Esteemed Member
Yes, but why is its lifespan shorter. :confused:
The color improvement is accomplished by 'doping' the mercury with different rare earth metals. The stability of these compounds is much weaker than the base mercury compound. Remember that each time the lamp is 'ignited the material is vaporized and returns to its solid state after it is turned off. As the material slowly decomposes, it eventually looses enough of its compounded form that will not be enough to sustain the ignitable(excitable) gas, thus the end of the lamp occurs.
 

Electric-Light

Senior Member
The color improvement is accomplished by 'doping' the mercury with different rare earth metals.
No, it isn't. The phosphor is phosphor. It simply glows in different bands when struck by 253.7nm UV. Its blended in such that the final color is acceptable when its blended with the visible light that low pressure mercury gives off along with UV.

The stability of these compounds is much weaker than the base mercury compoundRemember that each time the lamp is 'ignited the material is vaporized and returns to its solid state after it is turned off. .
we're not talking about metal halide lamps.
 

stevebea

Senior Member
3000K CRI 52 is the classic warm white phosphor. Been around for over half a century. The 80 CRI is RE80.

Neither GE nor Philips makes 40W in 3000K. They both make 32W in RE830 and 40W in classic cool white (62 CRI)
Neither makes any Circline in 3000K/WW.

http://www.usa.lighting.philips.com/pwc_li/us_en/connect/tools_literature/downloads/SAG-100_2009_Fluorescent.pdf

GE and Philips are all 12,000 hours.

What's the brand, model and date code? The same brand/model from 1995 won't necessarily have the same specs as 2009.
It was a Sylvania lamp..... I will get model and date code. When I called Sylvania the gentleman I spoke to was surprised they still manufacture a lamp with a CRI of 52.
 

Electric-Light

Senior Member
It was a Sylvania lamp..... I will get model and date code. When I called Sylvania the gentleman I spoke to was surprised they still manufacture a lamp with a CRI of 52.
Lighting industry isn't quite in touch with the internet as consumer goods industry. Usually new products are out there before its on the internet catalog. Osram Sylvania's website is so antiquated in design its such a PITA to search it.

FC12T9/WW/RS, 32W #20037, 52 CRI, 3000K 15,000 hrs.
I didn't find a 3,000K FC16T9 40W in OSI catalog.
 
Top