The Oldest Light Bulb: Centennial Light Bulb

By dlumpkin on 11/11/2015

oldest light bulb

At HomElectrical, we are passionate about light bulbs. We want to provide you, our customers, with energy-efficient, long-lasting light bulbs at a great price. This is our passion at HomElectrical. So we get really excited when we hear about long-lasting light bulbs. This did inspire a question...

oldest light bulb

What is the oldest light bulb still in use?

After some research and some very interesting reading, we discovered that the oldest working light bulb is found in Livermore, California at Fire Station 6. The light bulb has been working for 114 years and has survived several power failures and even some moves from former fire stations.

The light bulb, which you can read more about the bulb at the official website, has a live-feed webcam so you can see it in action! Originally the bulb burned at around 60 watts but currently burns at 4 watts, which might partially explain the amazing longevity. Tours are given at the firehouse for anyone interested in seeing the bulb in-person and books are available at stores and online.

thought experiment time

We like to ask interesting questions here at HomElectrical. We wanted to know what the oldest working light bulb was and we found it. We are not done asking questions, though. This cool discovery LED us to ask another question...

What would the LED equivalent be to the Centennial Light Bulb? How long would it be burning for?

The average lifespan of an incandescent light bulb is around 1,200 hours (around 50 days of continuous use). The Centennial Light Bulb has been burning well beyond the average at 998,640 hours (or 114 years, since June 2015). The average lifespan of an LED bulb is around 8,000 hours (333.3 days of continuous use).

If we multiply 1,200/998,640 by 8,000/X we will be able to find the hypothetical lifespan of this super-bulb. We come up with 7,989,120,000 equaling 1,200X and then we divide by 1,200 to find X (which will tell us the lifespan in hours). The result is 6,657,600 hours or 760 years. That is more than three times as old as the United States has been a country. Let that sink in... 


If there was an LED that was as efficient as the Centennial Light Bulb it would be in use for nearly three quarters of a millennium. (760 years to be exact)

We crunched the numbers and the results are in: If there was an LED bulb that had the same efficiency rate as the Centennial Light Bulb, it would burn for a crazy amount of time. Here is the breakdown:






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