IES TM-28-14

The objective of this Technical Memorandum is to provide guidance and recommended procedures for sampling, test intervals and duration, and a method for long-term luminous flux maintenance projection for LED lamps and luminaires. The intent is to help product manufacturers and users, standard developing bodies, and other organizations to avoid any unnecessary burdens related excessive product testing.

Typically, LED sources test data are available for at least 6000 hours prior to the design of lamps or luminaires with thejm. This provides the starting information for the luminous flux maintenance projection according to the combined method. That method also takes into account any detectable further contribution from the remaining lamp or luminaire components, rather than using only LED sources test data as a proxy. As a result, the luminous flux maintenance projection for the lamp or luminaire can begin as early as 3000 hours into their testing, when the protocol proposed by this document is followed.