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For as long as we’ve been putting light bulbs in our homes, we’ve been replacing bulbs as they burn out. Flip a switch and a light that used to work just fine no longer does. Incandescent lamps had the dubious benefit of having an evident way of determining when it was time to replace them. Things aren’t quite so simple for LEDs.

What it comes down to is a fundamental difference between catastrophic failure and practical failure. Incandescents are prone to catastrophic failure. When a light simply ceases to function from one instant to the next, like when an incandescent filament breaks, that’s catastrophic failure. While LEDs can fall victim to catastrophic failure, usually due to faulty internal components, it’s much more likely you’ll run into practical failure with your LED lamps.

Practical failure occurs far before an LED lamp burns all the way out. Unlike incandescents, LEDs gradually dim over time. As such, rating an LED for lifespan with catastrophic failure in mind is not useful. The light will cease to be practically operational well before it ever burns out completely.

LED lifetime expectancy ratings are instead based on the amount of time it’s estimated to take for the light to lose 30% of its luminosity. The reality is that as the light dims over time, you may not notice as the change will be gradual. In some cases it may not matter that the light is functioning at less than optimal brightness. But in commercial settings or when lighting stairs or otherwise dimly lit exterior areas, brightness counts.

Two important factors to consider when looking at the useful life of an LED lamp are lumen maintenance and the specific light’s L70 rating. Lumen maintenance is an approach of measuring the light output (lumens) of a brand new light source and comparing that with its light output after a certain period of time. L70 and L50 are examples of lumen maintenance – benchmarks for when 70 or 50 percent of a lamp or fixture's total light output remains. According to LEDs Magazine, the L70 of a light can be thought of like this:

“Rated lumen-maintenance life is measured in hours with associated percentage of light output, noted as Lp. In other words, L70 of 30,000 hours means that the tested LEDs produce 70% of the initial light output at 30,000 hours. If an LED has L50 of 30,000 hours, its lumen output decays faster than one with L70 of 30,000 hours.”

Many of SunLake’s LEDs have a lifetime expectancy of 20+ years. It is extremely doubtful that you’ll remember vividly the light output from a bulb you installed 20 years ago compared to today. While the bulb may still function, it will be reaching its L70 by that point and should be replaced. Keep in mind that SunLake offers a 10-year warranty on nearly all its products. Should a light fail in that time, we’ll make it right.