Why is the Centennial Bulb Still Burning? The Secrets of Livermore’s 120-Year-Old Lightbulb

The Centennial Bulb, also known as the Livermore Light Bulb, has perplexed scientists, engineers, and enthusiasts alike for over a century.

Installed in 1901 at the Livermore-Pleasanton Fire Department in California, the light bulb has been burning continuously for more than 120 years. It has outlived its creators, numerous light bulb technologies, and even the fire station where it was initially housed.

But what is the secret behind the longevity of this miraculous bulb? In this blog post, we’ll delve into the factors that contribute to the endurance of the Centennial Bulb and discuss the lessons we can learn from it.

Handmade Filament

One of the main factors contributing to the Centennial Bulb’s longevity is its unique filament. Unlike modern, mass-produced light bulbs, Shelby Electric Company carefully handcrafted the Centennial Bulb using a carbon filament.

This particular filament is much thicker and more durable than the tungsten filaments commonly found in today’s incandescent bulbs. As a result, the filament is less prone to breaking or evaporating, allowing the bulb to continue shining for more than a century.

Low Wattage

Another key factor in the Centennial Bulb’s long life is its low wattage. The bulb operates at a mere 4 watts, significantly lower than the 40 to 100 watts typical for incandescent bulbs. It was originally designed to operate at 60 watts, but its wattage has faded over time.

This reduced energy consumption generates less heat, minimizing the stress on the filament and lowering the risk of it burning out.

Continuous Operation

Surprisingly, the fact that the Centennial Bulb has been continuously burning for over 120 years contributes to its longevity. Frequently turning a light bulb on and off can cause temperature fluctuations that weaken the filament, eventually leading to its failure.

By remaining continuously lit, the Centennial Bulb has avoided these temperature changes and the associated wear and tear.

Nitrogen Gas

The atmosphere inside the bulb also plays a crucial role in its enduring life. The Centennial Bulb is filled with 80% nitrogen gas, which is less reactive than the argon or krypton gas mixtures used in modern incandescent bulbs.

This inert environment helps to preserve the filament, preventing it from deteriorating as quickly as it would in a more reactive atmosphere.

Design and Quality

Lastly, the design and quality of the Centennial Bulb have contributed to its exceptional lifespan. The bulb’s thick hand-blown glass envelope and sturdy brass base have protected it from external factors such as temperature fluctuations, humidity, and physical damage.

Moreover, the handcrafted nature of the bulb ensured a level of care and attention to detail that is difficult to replicate in mass-produced products.


The Centennial Bulb stands as a testament to the durability and quality of early 20th-century craftsmanship. Its unique filament, low wattage, continuous operation, nitrogen-filled atmosphere, and careful design all contribute to its incredible longevity.

As we continue to push the boundaries of technology and develop more energy-efficient and long-lasting lighting solutions, the Centennial Bulb serves as a reminder of the importance of quality, attention to detail, and thoughtful design in the pursuit of truly sustainable products.

Thomas Smith

Thomas Smith is a food and travel photographer and writer based in the San Francisco Bay Area. His photographic work routinely appears in publications including Food and Wine, Conde Nast Traveler, and the New York Times and his writing appears in IEEE Spectrum, SFGate, the Bold Italic and more. Smith holds a degree in Cognitive Science (Neuroscience) and Anthropology from the Johns Hopkins University.

Leave a Reply

Back to top button