How do we know?
↻ One of the pages with a moving picture
One light bulb has been glowing since 1901.
- In an old-style bulb, electricity flows through a thin wire called a filament. It is usually made of tungsten.
- The filament resists the moving electrons. It gets very hot and glows.
- Only about 10% of the energy becomes light. Most of the rest comes out as heat.
- An LED works another way. Electrons and empty spaces called holes meet and pair up, and that gives off light.
A light bulb at Fire Station #6 in Livermore, California, has been glowing 24 hours a day since 1901, now at just 4 watts. Guinness World Records lists it as the longest-burning light bulb.
In 2011, fans celebrated its one millionth hour. A webcam lets people check on it.
LED bulbs last many times longer than old-style bulbs, and they use much less energy.
Wow number
Many times longer: that’s how long LED bulbs last compared with old-style bulbs. They also use much less energy.
Myth or fact?
Old-style bulbs turn most of their energy into heat. Fact. They waste about 90% of their energy as heat.
LED bulbs get just as hot as old-style bulbs. Myth. LEDs give off almost no heat. They are cool to the touch.
Think about it
The Livermore bulb is rarely turned off. Turning a bulb on and off makes it heat up and cool down. Why might that wear it out?
Where in the world?
Livermore, California, USA where a light bulb at Fire Station #6 has been glowing 24 hours a day since 1901, now at just 4 watts — 37.6819° N, 121.768° W.
Where these facts come from
Every number on page 96, and who measured it
This page tells us how a hot tungsten filament glows and wastes most energy as heat.
Molecular Expressions Microscopy Primer: Physics of Light and Color - Incandescent Lamp Filaments: Interactive Tutorial — Molecular Expressions, a science site from Florida State University
micro.magnet.fsu.edu/primer/java/lightsources/filament/index.html
We checked it on 31 October 2026
This page tells us how the filament gets hot enough to glow.
How Do Holiday Lights Work? — The U.S. Department of Energy
energy.gov/articles/how-do-holiday-lights-work
We checked it on 31 October 2026
This page tells us how much less energy LEDs use and how long they last.
The U.S. Department of Energy
energy.gov/sites/prod/files/guide_to_energy_efficient_lighting.pdf
We checked it on 31 October 2026
This page tells us about the bulb in Fire Station #6 that has glowed since 1901.
On the bright side, famous light bulb still shining after over 100 years in fire station — Guinness World Records, which keeps lists of world records
guinnessworldrecords.com/news/2025/2/on-the-bright-side-famous-light-bulb-still-shining-after-over-100-years-in-fire-station
We checked it on 31 October 2026
This page tells us that the Livermore bulb holds the world record.
Longest burning light bulb — Guinness World Records, which keeps lists of world records
guinnessworldrecords.com/world-records/longest-burning-light-bulb
We checked it on 31 October 2026
This page tells us how LEDs make light.
Scientists Say: LED — Science News Explores, a science magazine for kids
snexplores.org/article/scientists-say-led
We checked it on 31 October 2026
Has this changed?
How a bulb makes light is not going to change, but the bulbs are: LEDs are replacing old-style bulbs in many homes.
The Livermore bulb is still glowing, so its record keeps growing.
Words from this page
- filament
- The thin wire inside an old-style bulb that glows when it gets hot.
- LED
- A kind of bulb that makes light when electrons and holes meet. It uses much less energy.
Try it!
Go on a bulb hunt at home.
1. With a grown-up, count the lamps and lights in your home. 2. Ask your grown-up to check which bulbs are LEDs. (Don’t touch any bulbs!) 3. Make a tally: LED or old-style?
What happens: you find out which kind your home uses most. LEDs waste far less energy as heat.
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