Lifetime vs. Reliability of LEDs

LED lighting lasts for an average of 50,000 hours, with some lasting up to 100,000 hours. As incredible as this fact is, it does not mean that LED-based fixtures are magical products that do not need to be touched for 50,000 hours. I, Dr. Bulb, wish this were true!

The Department of Energy (DOE) recently released a fact sheet on the lifetime vs. reliability of LED products to explain the current methods and standards of LED lighting. It also acknowledges the shortcomings of LED standards.

The unfortunate reality: Nothing lasts forever—including lighting products! Products either fail in a “catastrophic” way, or a in a “parametric” way—meaning they stop producing an acceptable quantity of light.

Conventional lamp-based lighting systems (incandescent, fluorescent, or HID) typically fail when a lamp “burns out.” The other system components last longer than the lamp and have lifetimes that are not dependent on the lamp. Because of this, lamp replacement is easy.

It’s another story for LED lighting. The super long life of LEDs creates a tricky situation, since LED systems like those in LED bollard lights are not necessarily lamp based. The main problem is the fact that existing methodology is focused on lumen depreciation as the only failure mechanism, and NOT the rating of elements that go into the system beyond the light source. The typical approach to defining lifetime is no longer applicable to LED systems.

The DOE fact sheet defines Lifetime and Reliability as:

Lifetime: “A statistical measure (or estimate) of how long a product is expected to perform its intended functions under a specific set of environmental, electrical and mechanical conditions. Lifetime specifications can only describe the behavior of a population; any single product may fail before or after the rated lifetime.”

Reliability: “A statistical measure (or estimate) of the ability of a product to perform its intended functions under a specific set of environmental, electrical, and mechanical conditions, for a specific period of time. Reliability estimates for the entire useful life phase of a product are commonly reported using MTBF or MTTF.”

The solid state lighting industry has come a long way in establishing standards for testing and rating LED components and systems, but there is still no ideal way to rate system life expectations—yet!

It is important for the lighting industry as a whole to understand the accurate portrayal of LED product lifetime and reliability. Without the right information, ratings of LED products can seem misleading. Learn more here.

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