Recommendation 1 of the 16th CCPR (2001)

Photometric standards of the International Bureau of Weights and Measures (BIPM)

The Consultative Committee for Photometry and Radiometry,

considering that

• it pertains to the BIPM to disseminate the best possible realizations of the SI units;
• the values attributed to the standards of luminous intensity and luminous flux maintained by the BIPM should both promote worldwide uniformity and be consistent with the 1979 definition of the candela;
• the Mutual Recognition Arrangement (MRA) implies that the realizations maintained and disseminated by the BIPM be recognized worldwide;
• the means of the results of the key comparisons of the national realizations of the candela and the lumen, CCPR-K3.a and CCPR-K4 (both approved following the 15th meeting of the CCPR in 1999), represent the most reliable reference values;
• the BIPM has already in the past maintained as references for the photometric units sets of standards the values of which were established from the results of international comparisons;
• the value of luminous intensity attributed to the standards maintained by the BIPM since 1985 is 0.30 % greater than the key comparison reference value of CCPR-K3.a;
• the value of luminous flux attributed to the standards maintained by the BIPM since 1985 is 0.36 % greater than the key comparison reference value of CCPR-K4;

recommends that

• the BIPM continue, as in the past, to maintain and disseminate realizations of the photometric units of the SI representing the means deduced from comparisons;
• the values attributed to the standards maintained by the BIPM as representing the candela and the lumen be reduced, with effect from 1st January 2002, by 0.30 % and 0.36 % respectively, so as to conserve and disseminate the reference values of the relevant key comparisons;
• these adjustments be published.

DOI : 10.59161/CCPR2001REC1E