Typically, incandescent bulbs last between 1,000 and 2,000 hours. Even LED bulbs, which are much more durable, usually last between 25,000 and 50,000 hours.
But hanging from the ceiling of the Livermore Fire Station in California is the world’s longest-lasting light bulb, which has been burning for over 120 years. What’s even more surprising is that this incredible lifespan belongs to an incandescent bulb, not some special new technology.
Despite its age, the bulb’s remarkable longevity only caught public attention in 1972 when a fire station employee told a local newspaper about the round bulb that had been continuously lit for years, with no one knowing its origin. Mike Dunstan, a young reporter for the Tri-Valley Herald, started investigating and was amazed by what he found.
It turns out the bulb has been glowing almost nonstop for over a century, only turning off briefly a few times, when it was moved in 1903, for about a week in 1937, and again in 1976 during another relocation. In recent years, it has also gone out a few times due to short power outages on its dedicated circuit.
Since then, this special bulb has drawn a lot of attention. The Guinness World Records officially recognized the 30-watt bulb as the “longest-lasting incandescent bulb in the world.” It has been featured in numerous major news outlets and TV programs.
In 1976, when it was moved to its new home at Livermore Fire Station No. 6, a crowd of police officers and firefighters eagerly waited to see if the bulb would light up again. Deputy Fire Chief Tom Brandall recalled, “The city electrician installed the bulb and connected the power. For about 22 to 23 minutes, it didn’t light up. The crowd held their breath. Then the electrician grabbed the switch and shook it hard, it came back on.”
Since then, the bulb has been under constant camera surveillance to ensure it stays lit at all times. In fact, in the following years, a live stream called “BulbCam” was launched so everyone could watch it in real time. On Facebook, there are over 9,000 groups dedicated to this bulb.
Despite its long life, the bulb has never been praised for its brightness. Early on, it was about as bright as a 60-watt bulb, but now it only matches the output of a 4-watt bulb. However, this shortcoming is offset by its unique design.
Master designer Adolphe A. Chaillet created this bulb, which was produced by his company, Shelby Electric Company. What makes it special is its carbon filament, which lasts longer and produces less heat than Edison’s tungsten filaments. Still, this doesn’t fully explain its incredible lifespan.
Many research groups, from the Mythbusters team to NPR, have tried to figure out why this incandescent bulb lasts so long. But so far, all attempts have only deepened the mystery.
In 2007, physics professor Debora M. Katz managed to acquire a Shelby bulb similar to the century-old one and discovered that its filament is eight times thicker than that of modern incandescent bulbs.
“I compared it to the filament thickness of modern bulbs. It turns out modern filaments are coils about 0.08mm in diameter, made from wire about 0.01mm thick. I didn’t realize this until I looked under a microscope. The Shelby bulb’s filament thickness is about the same as the coil diameter in modern bulbs, 0.08mm,” Katz explained.
Katz believes the thicker filament might be why the bulb lasts so long. She also thinks its longevity benefits from being kept on continuously rather than switched on and off daily, which stresses the filament by heating it up repeatedly.
But in the end, Katz and her students couldn’t pinpoint exactly what causes the bulb’s extraordinary lifespan. Justin Felgar, one of Katz’s students, suggested that to truly understand it, the bulb would need to be dismantled and tested in the U.S. Naval Academy’s particle accelerator, a costly process that hasn’t been done yet, as long as the bulb keeps shining.
Compiled from various sources
