ANSI C78 376:2001 pdf download.Specifications for the Chromaticity of Fluorescent Lamps.
ANSI C78 376 covers the objectives and tolerances for the chromaticity of T8, T10 and T12 fluorescent lamps with a nominal loading of from5toi0 watts per foot at their normal 100 hour rating point. This standard alsc covrs some corrpact lamps, where noted. The colors included are 2700K, 3000KIwarm ivhite, 35O0K/whit, 4000Kl4lOOKIcool white, 5000K, and 6500K/daylight. The lamp under tet shall be operateJ under reference conditions as specified in ANSI C78.375 Guie for Operation of Fluorescent Lamps and in the relevant C78 lamp standard.
2. Color specification basis
The x and y coordinates used n this specification are based on the 1931 CIE* Chromaticity Diagram. Lamps shall be rated in terms of the measurements standards established by the National Institute of StandardsEand Technology. Tolerances are based on the ellipses defined by David L. MacAdam in his piper “Specification of Small Chromaticity Differences” printed in Journal of the Optical Society of America, vol 33, no.1, Jan 1943, pp 18-26.
* International Committee on lllumination
3. Nominal color temperature
Values of correlated color temperature (CCT) will vary within a chromaticity tolerance ellipse since they are a function of color coordinates. For colors which are designated by nominal color temperature, the value shall b based on the CCT of the objective chromaticity.
For new colors, the nominal v tue of the color temperature shall differ from the CCT of the objective chromaticity by less than 100K. For a color with a nominal color temperature generally established prior to this stand rd, the value may be retained when it differs from the CCT of the objective chromaticity by a sli htly greater amount.
4. Objective chromaticities
The objective chromaticities are shown in Table 1.
5. Chromaticlty tolerancs
For the lamps covered by this tandard the chrón’ratiéTtytoterance is defined by a 4 step MacAdam ellipse. The ellipse are shown in figures 1 through 6.
In the construction of these ellipses the data shown in Table 2 are used. The values of g11 2g12, and g22 are taken from McAdam’s paper referred to above. They are the basis for calculating è, a, and b. è is th angle between the major axis of the ellipse and the x axis. a and b are major and minor serhi-axis of a one step ellipse, respectively.
ANSI C78 376 pdf download.