TM-28-14 is meant to serve as a guide and overview for “sampling, test intervals and duration, and a method for long term luminous flux maintenance projection for LED lamps and luminaires using data obtained when [a] product is tested according to IES LM-84: Approved Method for Measuring Luminous Flux and Color Maintenance of LED Lamps, Light Engines, and Luminaires and LM-80: Approved Method: Measuring Lumen Maintenance of LED Light Sources. According to Rita Harrold, IES Director of Technology, “This standard [ TM-28-14] is meant to help both manufacturers, and users, and standards developing bodies to avoid burdens related to excessive testing by balancing testing time effort and statistical rigor.”
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