IESNA categorizes ‘cutoff ’ into four different classifications: Full Cutoff, Cutoff, Semi-Cutoff and
Non-Cutoff.
Below are the definitions according to IESNA along with illustrations:
Full Cutoff - A luminaire light distribution with zero candela (intensity) at an angle of 90 degrees or above. Additionally, the candela per 1000 lamp lumens does not exceed 100 (10%) at a
vertical angle of 80 degrees.
Semi-Cutoff - A luminaire light distribution where the candela per 1000 lumens does not exceed 50 (5%) at an angle of 90 degrees or above. Additionally, the candela per 1000 lamp lumens does not exceed 200 (20%) at a vertical angle of 80 degrees.
Non-Cutoff - A luminaire light distribution where there is no candela restriction at any angle.
