IES TM-19-17

Designers of lighting systems are often faced with wide variations in the presentation of luminaire photometric test data. Designers also occasionally find that the calculated values do not agree with measured values. This discrepancy can be attributed to a number of factors. Some of the common problems, such as improper installation methods, can be identified on site and corrected. However, discrepancies in photometric performances are often attributed to out-of-date test reports, manufacturing defects, component tolerances (lamp, ballast), and improper prorating during calculations.

Therefore, it is necessary to establish more-consistent presentations and verifications for luminaire photometric data.

This document provides recommendations to luminaire manufacturers for uniform presentation of test reports of printed or electronic roadway luminaire photometric data. For large installations, it recommends consideration of random sampling of luminaires for photometric testing, and it recommends procedures for prorating photometric test results for calculations where applicable. This Technical Memorandum (TM) does not specifically address computer programs that are used to read and supply formatted electronic photometric data.