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Joe Pack
01-24-2004, 9:30 PM
I am planning to switch out my old magnetic T-12 ballasts for newer electronic T-8 ballasts and bulbs. My problem is that I don't know how to interpret the color rendering index numbers (CRI) and the temperature (3000-5000K).

These fixtures are in kitchen, bathroom and utility areas. I definitely do not want the "cool" yellow/green lighting that the 99cent bulbs provide. Instead, I want to move toward the warmer or more natural light end of the spectrum. I currently use "warm white" bulbs that bring out the warmer colors in our cherry cabinetry and furniture.

I can buy bulbs in a 700 series, 800 series and 900 series (900 is too expensive - approaching $15/bulb, but the 700 and 800 series are about $2.60 each in case quantities). The 700 and 800 series are available in 3000k, 4000k and 5000k.

Can any of our lighting experts..........(Big groan here) shed a little light on this for me?
In short, what do you recommend for use in our kitchen, bathrooms (1 with no natural light) and utility room?


Messages In This Thread

Ken Garlock
01-24-2004, 10:37 PM
Hi Joe. Let me add what little I know about the subject. I did some research on the very subject when addressing the lighting for my shop.

First color temp. Color temperature is measured in degrees Kelvin, where zero degrees Kelvin is absolute zero. When passing current through the filament of a bulb it begins to heat and when sufficiently hot begins to give off light. As the filament continues to heat it goes from red to white and eventually toward blue. For each temperature the filament will emit a specific color. For photographic purposes, white is defined to be 6500 degrees Kelvin. Anything hotter(>6500K) has a blue tint, anything cooler (<6500K) has a red tint. As an aside, most TV sets are set to about 8000-9000 deg. Kelvin at the factory. Apparently people perceive a blue-ish tint to white to be better, I don't know why. :confused: So, a 5000K bulb will be closer to the defined "white" than a cooler bulb will be.

Second CRI. CRI, Color Rendition Index, has a range of 0-100. It is a measure of how close a bulb's light is to sunlight when viewing a object. A bulb with an index of 100 when shined on a object gives the same color rendition of said object as natural sunlight would. In theory, you can switch between the two and not notice a difference. In practice, a CRI above 80 is acceptable, and a 90 or more is desirable.

As far as fixtures go, you will want a fixture that uses a T-8 bulb. Personally, I went with the electronic ballasts as I think they are better and less noisy. You do not want a T-12 fixture. :(

I suggest that you take a look at the company where I bought my bulbs:

Full Specturm bulbs (http://www.fullspectrumsolutions.com/Fluorescent.htm)

Yes, they cost more, but will last longer, and give good quality light, IMO.

Hope this help....

Joe Pack
01-25-2004, 12:47 AM
Thanks, Ken. Your explanation makes more sense than some of the techy web pages I have been looking at.

Joe Pack
01-25-2004, 12:48 AM
Thanks, Ken. Your explanation makes more sense than most of the techy web pages I have been looking at.

Sorry 'bout the instant message thing...I hit the wrong button.