L90

L90 is a designation used in several fields, often serving as a threshold or label in performance specifications. The most widely cited use is in LED and solid-state lighting, where L90 denotes a lumen maintenance life goal.

In lighting applications, L90 refers to the time, typically measured in hours, at which a luminaire’s light output declines to 90 percent of its initial value under defined test conditions. This metric is used to compare products, support reliability claims, and inform warranty expectations. Test conditions can vary by standard and manufacturer, but they generally specify drive current, ambient temperature, and measurement procedures. L90 is commonly reported alongside other maintenance metrics such as L70 or L80, which indicate different brightness thresholds.

L90 values are influenced by factors including operating temperature, electrical drive conditions, and manufacturing quality. Higher temperatures and aggressive drive currents tend to shorten the L90 life. Because testing protocols and environmental assumptions differ, direct comparisons between products should consider the exact test conditions and the standard used.

Beyond lighting, L90 can appear as a general designation in other contexts, such as model numbers, part codes, or route identifiers, where its meaning is entirely context-dependent. As a result, the precise interpretation of L90 should be determined from the relevant documentation or specification accompanying a given use.