Lamp Life Expectancy
Life expectancy is defined as the number of hours of operation for a lamp until 50% of them fail. This means that it is possible for some lamps to fail after a short amount of time and for some to last significantly longer than the rated lamp life. This is an average (median) life expectancy. Production tolerances as low as 1% can create a variance of 25% in lamp life. For LEDs, lamp life is when 50% of lamps have lumen output drop to 70% or less.
Lamps are also sensitive to switching cycles. The rapid heating of a lamp filament or electrodes when a lamp is turned on is the most stressful event on the lamp. Most test cycles have the lamps on for 3 hours and then off for 20 minutes. (Some standard had to be used since it is unknown how the lamp will be used by consumers.) This switching cycle repeats until the lamps fail and the data is recorded. If switching is increased to only 1 hour on, the lamp life is usually reduced because the number of times the lamp has been turned on has increased. Rooms with frequent switching (bathroom, bedrooms, etc.) can expect much shorter lamp life than what is printed on the box.
Read more about this topic: Electric Light
Famous quotes containing the words lamp, life and/or expectancy:
“Life is the lust of a lamp for the light that is dark till the dawn
of the day when we die.”
—A.C. (Algernon Charles)
“There was never a revolution to equal it, and never a city more glorious than Petrograd, and for all that period of my life I lived another and braved the ice of winter and the summer flies in Vyborg while across my adopted country of the past, winds of the revolution blew their flame, and all of us suffered hunger while we drank at the wine of equality.”
—Norman Mailer (b. 1923)
“If I had my life over again I should form the habit of nightly composing myself to thoughts of death. I would practise, as it were, the remembrance of death. There is no other practice which so intensifies life. Death, when it approaches, ought not to take one by surprise. It should be part of the full expectancy of life. Without an ever- present sense of death life is insipid. You might as well live on the whites of eggs.”
—Muriel Spark (b. 1918)