If a light bulb burns for 1000 hours, why am I always changing them?

Answer 1

There could be several reasons. Too much line voltage, or surges in line voltage, that can occur during lightning storms or when power is restored after an outage, will severely shorten the life of any incandescent lamp.

You can purchase a "button," to put between the base of the lamp and the socket it screws into, that will increase lamp life by half-wave rectifying the line voltage... essentially discarding half the available power. The penalty is much reduced light output. You can also purchase bulbs with higher rated voltage, for example 130 instead of 120 volts, that will also last longer at lower line voltages (110 - 115 volts).

Another bulb killer is shock and vibration. It seems like I have to change my porch lights every other week or so because the closing (slamming) of the doors literally shakes them to death. I've tried using so-called "rough service" bulbs and garage door opener bulbs but nothing seems to work well.

This seems to go along well with someone else's answer that turning the lamp on and off reduces its life. There is a huge thermal shock when a light bulb first lights. Although they are designed with doubly-coiled filaments, delicately supported on wires inside the bulb, the failure mode is always this: the filament breaks.

Less often, but especially for bulbs that burn undisturbed and continuously, the tungsten filament eventually sublimes until it is too thin to support its own weight. This can take considerably longer than the typical 1000 hour life stated on the carton. But one day you turn the light off then back on again and... POOF! it's gone.

If you can afford the initial cost and don't mind the totally unnatural spectral distribution of the light, compact fluorescent lamps are a better bargain than most incandescent lamps. And soon, white-light emitting diodes (LEDs) will be available with life times of 50,000 hours or more.

Answer 2

The manufacturer states an average life of 1000 hours. That is the middle of the life expectancy of a light bulb. Actually a light bulb can last from a few hours to more than 1500 hours. 1000 hours is like 5 months in reality for a light bulb average use. If a bulb that has been used for a while is bumped or moved, the filament breaks because it has become brittle, shortening the life.

Answer 3

It's been stated already, the filament becomes very brittle after it has been used (i.e. the first time you turn the light on it will get like this) and each time subsequently is subjected to this shock of thermal expansion. The weakest point along the filament will eventually be weak enough to pop. If you have the option (a variable-intensity switch) on the lamp, turn it up slowly and it should last longer. If they ever come out with rhenium filament bulbs (unlikely due to high cost of the metal) they will not experience this problem as this metal will not become brittle no matter how long it is in use, only thinning due to long use would get one of these.

Answer 4

You can sit in your car every night eating popcorn with the door open and listen to the victory 'ding' while waiting to see how long it takes for the light to burn back out. or the battery to die, which ever comes first! yes, I can change a burnt bulb. I use a special tool...... Called a Husband.

Answer 5

you leave them on too long and it's burning them out or your not using the right light bulb for the right socket!

Answer 6

It's the on/off that shortens their life. If left to burn continuously, you'd get your 1000 hours

Answer 7

don't handle the bulbs with your bare hands. the oils from your hands will cause the bulb to develop a hot spot.

Answer 8

Yea, all the above prety much. lol

Answer 9

good point

Answer 10

bad wiring??