In a quiet fire station in Livermore, California, a small tungsten-filament bulb has glowed almost continuously since the late 19th century, outlasting generations of firefighters, the building it first illuminated, and even the company that manufactured it. Known today as the “Centennial Light,” this bulb has burned for more than 120 years, defying modern expectations about the lifespan of incandescent lighting. Its endurance has turned it into both a historical curiosity and a symbol in a long-running debate about manufacturing standards, planned obsolescence, and the lost art of early electrical engineering.
The bulb traces its origins to the late 1890s, when it was produced by the Shelby Electric Company of Ohio. Shelby was renowned for crafting exceptionally durable carbon- and early tungsten-filament bulbs, many hand-blown and hand-wired, their filaments thicker and less stressed by heat than later mass-produced designs. The bulb that would one day become famous was purchased sometime between 1895 and 1901, likely by Dennis Bernal, who owned the Livermore Power and Water Company. After Bernal sold his business to the city in 1905, the bulb was transferred to the Livermore Fire Department, where it began illuminating a horse-drawn fire engine bay.
Firefighters noted even early on that the bulb behaved unusually. While other incandescent bulbs failed within a year or two, common for the era, the Shelby bulb continued to burn steadily. Over the decades, it survived fires, relocations, and electrical upgrades. It was carefully disconnected and rewired during station moves in 1903, 1937, and 1976. The bulb now hangs in Fire Station 6, protected by a power supply designed to avoid voltage spikes. Its appearance is humble: a small, pear-shaped bulb emitting a soft, ember-like glow at about four watts.
For much of the 20th century, the bulb’s longevity was a local curiosity. It wasn’t until the late 1970s and early 1980s that journalists and engineers began to investigate the phenomenon seriously. After confirming the authenticity of the original wiring and tracing archival photographs, engineers concluded the bulb was indeed the same one installed at the turn of the century. In 2010, Guinness World Records certified it as the longest-burning light bulb on Earth.
Scientific explanations for its longevity point to several factors. Early filaments, especially those crafted by Shelby Electric’s skilled glassworkers, were far thicker and operated at lower temperatures than modern incandescent bulbs. Running cooler significantly reduces filament stress, oxidation, and evaporation. The bulb has also benefited from an exceptionally stable electrical environment. The fire station maintained consistent voltage over the decades, and the bulb rarely experienced the power surges that typically end incandescent lifespans. Perhaps most importantly, it has almost never been switched off; the on-off cycling that kills modern bulbs has barely touched it.
Beyond engineering, the Centennial Light has taken on cultural significance. Some see it as evidence that early industrial standards were superior, while others argue it demonstrates how modern consumer goods have been optimized for cost rather than longevity. The bulb is frequently cited in discussions about planned obsolescence, particularly regarding the Phoebus cartel, a consortium of lightbulb manufacturers in the 1920s accused of deliberately shortening bulb lifespan to increase sales. While the Centennial Light predates those events, it stands as a counterexample to the lifespan targets that later dominated the lighting industry.
The bulb has also inspired a peculiar kind of reverence. Livermore firefighters treat it with near-museum care, monitoring it through a webcam and leaving it connected to a dedicated circuit. Tourists visit the station to glimpse the tiny bulb that continues to shine when countless successors have burnt out. In 2013, when the bulb briefly appeared to fail, locals panicked, only to discover it was a faulty power supply, not the bulb itself. Once connected to a new system, the glow returned.
Today, more than 120 years after first being switched on, the Centennial Light remains a soft point of illumination in the corner of a modern fire station. It is not bright, and it is not used for practical tasks. Yet its warm glow has outlived every electrical trend since Edison: carbon filaments, tungsten filaments, fluorescents, halogens, LEDs, and smart bulbs. It stands as an engineering anomaly, a historical artifact, and a reminder that some technologies, when crafted without compromise, can last far longer than anyone ever intended.
Sources & Further Reading:
– Livermore-Pleasanton Fire Department archival materials and Centennial Light documentation
– Guinness World Records certification records for the longest-burning bulb
– Shelby Electric Company historical catalogs and manufacturing descriptions
– Engineering analyses published by the Centennial Light Bulb Committee
– Historical studies on early incandescent bulb construction and filament durability
(One of many stories shared by Headcount Coffee — where mystery, history, and late-night reading meet.)
