Lightbulbs Can Last Centuries

And Why They Don't Make Them That Way

Longest-Burning Bulb On Record - 108-plus years!

Easy Way to Make Bulbs Last For Centuries

Longest-Burning Bulb On Record - 108-plus years!

The longest-lasting incandescent light bulb on record is at a fire station in Livermore, California. It was installed on June 8 1901, was still working on April 13 2010, was always on except for a time it was moved and for any power failures affecting it, and as far as I know it is still in use and working.

Details in the Centennial Bulb web site.

Easy Way to Make Bulbs Last For Centuries

Simply operate a light bulb at half its rated voltage. Get a 230V light bulb from Europe and operate it in the USA at 120V. Believe me, that will do the trick! Life expectancy is generally about inversely proportional to voltage to the 12th power. At half voltage, a light bulb will last something like 4,000 times its rated life expectancy - give or take.

Bulbs.com has 13 incandescents having voltage ratings anywhere from 220 to 277 volts here.

Why It Does Not Pay To Do So.

Having the filament run at a lower temperature reduces the energy efficiency of a light bulb. Even at usual operating temperatures for 750-1,000 hour lightbulbs, a tungsten filament produces about 93 percent of its radiation in the infrared. That does not mean good efficiency at producing visible light. With a lower filament temperature, the percentage of radiation in the infrared increases and the percentage of radiation in visible light decreases. A light bulb that is 6-7 percent efficient in producing visible light at full voltage is only about 2 percent efficient in producing visible light at half its rated voltage.

I consider it a safe bet that the Livermore "century bulb" is even less than 2 percent efficient at converting electricity to visible light.

Since the cost of producing a given amount of light with incandescent lamps is usually mostly the cost of electricity rather than the cost of the light bulbs, it does not pay to make them last extremely long.

What Does Pay Off!

In many but not all places, compact fluorescent lamps pay off - both by lasting longer than most incandescent lamps and by being generally 3-plus times as energy-efficient.
Please read these pages so you can avoid some disappointments as well as know where to get some of the better ones:

General Info by Sam Goldwasser.
Some Helpful Hints and Brand/Model-specific and application-specific advice, etc.

In office buildings, schools and hospitals, non-compact fluorescents (usually 4 feet long) are almost always used since these are more efficient than smaller sizes. Due to economies of volume production, 4-foot bulbs don't cost more than smaller sizes.

One way to minimize lighting cost is to use a smaller number of higher wattage light bulbs instead of a larger number of lower wattage ones. Minimize the bulb count as much as possible without making light distribution too uneven or exceeding the ratings of the fixture. (Many fixtures have a 60 watt bulb wattage limit!) You spend less by buying and replacing fewer bulbs. In addition, higher wattage bulbs tend to be more efficient than lower wattage ones - for one thing, thicker filaments can be operated at a slightly higher temperature for a given life expectancy. For another, with reduced per-watt bulb costs, the cost of bulbs becomes less important (compared to the cost of electricity) for higher wattages so higher wattage bulbs are designed to run hotter and lower wattage bulbs are designed to last longer (which makes them run less efficiently).

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Written by Don Klipstein.

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