An LED light never truly burns out; it simply dims over time.  The lighting industry uses the L70 standard rating as the life span for an LED.  L70 is measured in hours until the LED reaches 70% of its original light output (30% lumen depreciation).  Testing has shown that the life span of an LED under ideal conditions at a constant 25°C  is theoretically as long as 350,000 hours (calculated by extrapolating test data to reach the L70).  In reality, LEDs do not operate under ideal conditions and will not exist nearly long enough to find out when they would actually burn out.

Many factors reduce LED life span.  LEDs are heat sensitive, and good heat dissipation is key to extending the lifespan of an LED fixture.  LED fixtures are sometimes installed in areas without good air circulation, thus leading to higher operating temperature and affecting product life.  Each 20°C increase in temperature typically will drop an LED’s life span by 10,000 hours.  LEDs are typically enclosed with plastic protective lenses, but over time plastic lenses tend to degrade, turn yellow, and block-in heat.  LED drivers (often enclosed within the fixture for retrofit LED products) typically have a warranty of 5 years and often fail before the LED reaches its L70 life span.  Like the LED, drivers contain semiconductor components and are heat sensitive; outside of its rated operating range each 10°C temperature increase may reduce the driver’s lifetime by half.  In a retrofit LED, the heat generated by the driver adds to that generated by the LED and compounds the overall heat problem.

If an LED fixture is well designed, the L70 life span can usually be estimated to be around 60,000 hours.  This is much greater than the life span of incandescent, fluorescent, or HID lamps.  Sunlite products are designed to last over 60,000 hours because they have excellent heat dissipation and are made with glass lenses that do not degrade or turn yellow over time.