Correlated Color Temperature 6400K or 6100K.


First, Pardon me if I am sending to the wrong forum here, as this is the best one I could relate to my subject.
My question is related to CCT and chromaticity coordinates. I am not a lightening expert, my organization has received an offer for a CFL Lamps from one of the vendors stating that the CCT value is 6700 or 6400K; however the report they submitted indicates that the color coordinates are x=0.3185, y=0.3470, u=0.1952, v=0.4785, and that CCT is 6118, I can see is that 6118 is far away from 6400, is this range acceptable and can we still call it 6400K? as I know, color coordinates for 6400 are x=0.313, y=0.337.
They also mentioned that color tolerance is 5.1976 if this information helps.
If you were advised about this situation, would you consider the lamp having 6400K or 6100K?


Great question, and this is the perfect place to ask it.

Below is a handy screenshot I took from some NEC software that shows the relationship between the Kelvin temperature numbers and xy values. Sometimes, it’s nice to be able to visualize these spaces instead of just going by the numbers.

Another tool to use is the CIE color calculator at Bruce Lindbloom’s site:

There, the Kelvin calculation is 6114.5 (which is very close to your 6118).

In my estimation, this is too far away from 6400 to call it 6400.

A bigger question might be “will this work for my situation?” In many cases, people who want CFL tubes for ambient image viewing prefer to have a temperature close to 5000 Kelvin which is closer to daylight. If I wanted daylight illumination in my area, I would prefer 6100 to 6400.

Glad I haven’t messed up your forums, and
Thank You, it’s clear to me now.