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17-30-034

cut-off

technique used for concealing light source(s) and surfaces of high luminance from direct view in order to reduce glare, or to reduce light emission above the horizontal

Note 1 to entry: In outdoor lighting, cut-off classifications define the luminous intensity limits in two illumination zones that occur within the range of 80° to 180° above nadir. Light emitted in the 80° to 90° zone is more likely to contribute to glare, and light emitted above the horizontal is more likely to contribute to sky glow.

Note 2 to entry: In public lighting, distinction is made between full-cut-off luminaires, semi-cut-off luminaires and non-cut-off luminaires.

Note 3 to entry: This entry was numbered 845-10-29 in IEC 60050-845:1987.

Note 4 to entry: This entry was numbered 17-269 in CIE S 017:2011.

Publication date: 2020-12
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