Color Temperature in Fluorescent Lamps

What is color temperature?

Two fluorescent lamps may have a power of say 30W. This means that they will both give an incandescent equivalent of about 150W, and have the same brightness, but the type (or quality) of light they give could be vastly different, depending on their 'color temperature'. This is often quoted, in one way or another, to describe the type of light given by a fluorescent lamp.

What is white light?

Fluorescent lamps work by the ultra violet discharge inside the tube striking the coating, which then produces white light. White light is a mixture of all colors of the visible spectrum, but the mix can be different, and the more from the red end of the spectrum, the 'yellower' the light, the more from the violet end the 'bluer' the light . The coating of the tube is responsible for the type of light emitted. Different compositions of coating give different qualities of light ..

How is color temperature measured?

To make matters more complicated, this can be given as Kelvins (K) of the lamp, or as a color code. These are two ways of describing the same thing. The following describes various light sources:

– 1700K is approx. a match flame
– 1850K is approx. a candle flame
– 2700K or color code 827 is the color of most incandescent lamps and is often called warm white or very warm white
– 3000K or 830 is the color of most halogen lamps and is called warm white
– 3500K or 835 is the color of early morning or evening sunlight and is called white
– 4000K or 840 is the color of stronger light and is called cool white
– 6000K or 850 is the color of craftlight or daylight lamps and is called daylight white
– 6500K or 860 is the color of some specialist lamps and is called cool daylight
– 10000K is the approx. color of a bright day with blue skies.

Fluorescent lamps can be made between 2700K and 6500K. Generally the higher the color temperature, the more expensive the lamp, and the 'whiter' the lamp. Some people prefer a 'softer' yellowish tone for artificial lighting, and rooms with lots of reds and yellows. Others prefer a 'cooler' bluish tone, especially for rooms with lots of blues and greens. Close intrict work, such as sewing, embroidery, etc. benefits from high color temperatures, as do older people, whose eyesight is deteriorating.