How long does a bulb last?
Light bulb manufacturers adhere to a standard industry rating for light bulb life called “rated life.” The rated life is a measure of the median time in hours that it takes for a light bulb to burn out. This is the point in laboratory testing at which half the test bulbs have burned out and half the test bulbs are still burning. A 60-watt incandescent bulb may have a rated life of 1,000 hours. However, not all bulbs of this type will last exactly that long. That rated life is the median – the point in lab testing when 50% of the test samples have burned out and 50% are still burning.
