cool white lamps

[vincef]

Any one have an idea, why some cool white lamps would give off a warm white colour, do high frequency or switch start fittings effect the colour?

 

[nickblake]

they can when first switched on and cold , i have come across this on occasions and last week ,when i changed a load of ballasts to HF new end caps and cool white 840 tubes and when they were switched on they went a slight shade of pink but after about 1/2 and hour they changed to cool white and have stayed that colour ever since

 

[accordfire]

Any one have an idea, why some cool white lamps would give off a warm white colour, do high frequency or switch start fittings effect the colour?

Frequency will affect the colour of a fluorescent, halide, or even sodium fitting to some extent - the gas used needs to reach the correct temperature to burn the colour it was designed for. Also the starter may be under rated for the load if they're burning the wrong shade?

Cool white is a higher frequency burn than warm white - and frequency is key to how the atoms are "excited" inside the lamp - the faster, the higher the temperature, and hence the "bluer" the colour. Slower, the warmer, and more red.

You can often see this problem in switchgear designed for warmer tubes, when they're switched to higher light temperature tubes. What's probably happening is that the tubes aren't being run at full temperature, due to a switchgear limitation - mostly it's a case of changing the ballast for a unit that will cope.