L70 and L90
March 22, 2019
How long will an LED product last? Well, a good indication is the specification called L70. In this blog, we explain what it is and how it is derived.
What is Lumen Maintenance?
Lumen Maintenance is a measurement used to evaluate the decrease in light output of a bulb that occurs over time. LED life is defined as when the light bulb produces 70% of the initial lumens (L70). This measurement lets you know how long you can depend on an LED to provide an acceptable level of intensity as the day you installed it. Comparing L70‘s across products will allow you compare 2 products and determine which one should last longer.
What is an L90 Rating?
LED must maintain 90% of their initial lumens during their rated life. This value is tested by third party labs and after a running the product for a specific amount of time, the lab will calculate the L90 value. This report is typically called a TM21 report.
What is an L70 Rating?
Based on the L90 value determined in the L70, manufacturers ‘calculate‘ the L70 value which in essence is the maintenance of 70% of their initial lumens during their rated life. Please note, this is a calculated value because it is impractical for a product to run 10‘s of thousands of hours to determine the actual numbers.