LED Buying Guide(3) - LED Bulbs What You Need to Know

Bulb Lifetime

Initially when LED bulbs came out with no standards, manufacturers would claim lifetimes of 100,000 hours with no real testing. Since then the standard has been to scale back to 50,000 hours so as not to over-state claims. (Beware of bulbs that are rated at 100,000 hours unless they state specifically WHY they are rated at so high manufacturing process, heat sink materials etc., I would be wary of trusting this rating).

As of May 2009, Many of the LED manufacturers that we've spoken to, producing their 3rd generation LED bulbs are now starting to be more conservative and rating their bulbs at 35,000 hours, having gotten test results back from 1-2 years of testing. Rated at 35,000 hours, you can rest assured the manufacturer is not overstating their claims. Anything more than 50,000 hours...buyer beware.

The lifetime of an LED lamp is generally considered to be the point where the light output has declined to 70% of its initial output, measured in lumens. For example, a 300 lumen LED spotlight with a lifespan of 50,000 hours will have 210 lumens at the end of its lifetime. However, the lifetime of a bulb does not mean it is unusable, only that its light output has degraded to a certain point. The LED bulb may continue to be useful for several thousand hours past its stated lifetime. Unlike old-fashioned light bulbs, it is extremely rare for an LED light to simply burn out. Rather, it will gradually fade over time.

Color Temperature

As a general rule, you should use warmer light indoors, and whiter light outdoors. A color temperature of 2500-4000 Kelvin works great indoors. You should use a bulb with a color temperature of 5000-7000 Kelvin outdoors, as the whiter light allows your eyes to see better at night. White light in the 5000-7000 Kelvin range is also excellent for display cases, boutiques, artwork, or other settings where you need excellent color rendition.