Longest-lasting light bulb

The world’s longest-lasting light bulb is the Centennial Light located at 4550 East Avenue, Livermore, California. It is maintained by the Livermore-Pleasanton Fire Department. The fire department claims that the bulb is at least 121 years old (installed 1901) and has only been turned off a handful of times. The bulb has been noted by The Guinness Book of World Records, Ripley’s Believe It or Not!, and General Electric as being the world’s longest-lasting light bulb.

While it might seem astonishing that so many longest-lasting light bulbs have been so infrequently turned off, this is the precise reason for their longevity. Most of the wear and tear that leads to burnouts in incandescent light bulbs is caused by turning them on and off, not by burning them. Each time the bulb is turned on and off, the filament is heated and cooled. This causes the material of the filament to expand and contract, in turn causing micro stress cracks to develop. The more the light is turned on and off, the larger these cracks grow, until eventually the filament breaks at some point, in non-spectacular fashion, thus causing the light to burn out.^{[citation needed]} Another reason for the longevity of bulbs is the size, quality and material of the filament. Additionally, the consistency of the power delivery to the bulb and how little it fluctuates prevents the bulb’s filaments from being damaged by dirty power (brown-outs cause damage to electrical systems).