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How Long Do LEDs Last?

(March 2010) posted on Wed Feb 10, 2010

Nisa explains the “second-half syndrome.”

By Dr. Nisa Khan

As president of LED Lighting Technologies, Dr. M. Nisa Khan consults in the solid-state lighting industry and educates consumers about LED lighting. She has a bachelor’s degree in physics and mathematics, and master’s and Ph.D. degrees in electrical engineering. Email her at



Popularity begets popularity. Particularly today, because of the countless electronic communication systems that quickly dispatch popular news and information across the globe. Ask Tiger Woods. Today, the news travels – and aggrandizes – quickly.
In the scientific arena, popularity describes a matter, concept or idea that races across a given field, and later, perhaps, the nation or world. However, with science, a rise in popularity does not indicate a rise in validity.
For example, when a colleague recently remarked that LEDs last forever, I lightheartedly, but truthfully said only half will last a portion of forever. My reason? Lighting-industry professionals comprehend that a specific lamp series may be publicized to have a three-year life, but also recognize that only half the lamps are expected to last that long. The remainder may last only a fraction of three years. Some call this the “second-half” syndrome.
The “LED lamps operate interminably or almost forever” belief unfurls because casual observers read LED manufacturers’ claims of 100,000-hour lifespan. Unfortunately, such claims and beliefs have become popular, but nothing could be further from the truth. A classic fallibility example is the partially darkened, LED-arrayed, traffic lights we sometimes see.
Too often, the “second-half” failure syndrome frustrates signage and luminaire makers, especially if the lamps burn out within months or days of installation.
If prosaic traffic-signal LEDs experience lifespan problems, what can we expect from modern, but not-so-well-tested LEDs, especially the much-lauded, white ones?


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