In Livermore, California, a remarkable light bulb has defied the odds for over a century. Known as the Centennial Light, this carbon-filament bulb has been glowing since 1901, earning it the title of the world's longest-burning light bulb, recognised by Guinness World Records.

Origins of the century-old bulb

The Centennial Light's story began in the late 1890s at the Shelby Electric Company in Ohio, where it was hand-blown using a design patented by French engineer Adolphe Chaillet.

It was first installed at the Livermore Power and Water Company in June 1901. When the company's owner, Dennis Bernal, sold the business, he donated the bulb to the Livermore Fire Department.

Since then, it has been moved a few times, with its final relocation in 1976 to Fire Station 6. Each move was treated with reverence, including a full police and fire truck escort.

Now 123 years old, the bulb still shines, albeit dimly, with the light of a 4-watt nightlight. Its original wattage was either 30 or 60 watts, but its steady glow continues to captivate.

While the bulb has experienced brief interruptions due to power outages, renovations, or equipment failures, it has never truly burned out.

How has it lasted so long?

Many believe the the Centennial Light's extraordinary longevity stems from its robust, handcrafted carbon filament, which is thicker and more durable than modern tungsten filaments. Operating at just 4 watts, it generates minimal heat, reducing filament stress and preventing burnout.

Its continuous operation is also believed to have preserved it, avoiding the wear caused by frequent on-and-off cycles. The bulb's nitrogen-filled atmosphere further slows filament deterioration, offering a more stable environment than the argon or krypton gases used in modern bulbs.

It is also believed that the bulb's thick, hand-blown glass casing and sturdy brass base protect it from damage and environmental factors, a testament to the 20th century craftsmanship of the Shelby Electric Company.

According to a blog post by British bulb company Lightbulbs Direct, today's Class A LED bulbs, for instance, are celebrated for their efficiency and durability, with lifespans of up to 50,000 hours. That's more than six times longer than compact fluorescent lamps (CFLs) and far beyond the life expectancy of halogen and incandescent bulbs. Yet, even these advanced designs pale in comparison to the Centennial Light's century-plus endurance.

For those curious about this marvel, the Centennial Light has a dedicated following, complete with a 24/7 live webcam, which you can find here.

The Centennial Light, because of its enduring history, remains a symbol of engineering ingenuity and a reminder of a bygone era when things were built to last.