LED there be light

Not only has this hand-blown bubble of glass from sunny California made it into the Guinness Book of Records (as the ‘longest burning light bulb’) but it has also been given its own website where you can see if it still works. And indeed over the years they have had to change the webcam times but the bulb keeps burning on. The carbon filament bulb was hung from the ceiling of the firehouse in 1901. It shone out with a light of 60 watts at the time, though today the antique only manages to put out around four – but it’s still enough to illuminate the fire engines at night. The proud firemen entrusted with its care have at regular intervals even held events to celebrate the uninterrupted glow. In 2001 it was the bulb’s 100th anniversary and in 2011 the 110th birthday party was held. Rather than wait to 2021, in 2015 it was decided to throw a bash for the millionth hour of the fire-fighters forgetting to turn the thing off.

Rather surprisingly this record-breaking light is not fenced off like the Mona Lisa in the Louvre, but anyone can go and put their grubby hands on it. It’s even written on the webpage that visitors should: ‘Go to the rear of the station and ring the bell. If they are in someone will answer the door. Otherwise you can see the bulb if you look through the window up on the top of the wall to your left.’ LED producers must be looking on in envy. The light source of the 21st century is undoubtedly long-lasting, economic, with colours that can be tuned to be beautiful to the eyes but... Well, it’s not exactly clear how long diodes will work since so far no one has actually witnessed a burn out. And not for lack of trying. The producers spent 10,000 hours (just over a year) staring at their creation but eventually grew bored of making themselves blind so they decided it was time to start shipping and selling their LEDs instead. So using lots of top secret technical data that we obviously are not privy to, they came up with their best guestimate of seven years. Good though that may be it still doesn’t quite match up to the 120 years of that piece of glass in California. And even that seven years comes with one mighty caveat. Bear with me while I bore you with a little physics. Contrary to popular opinion Nikola Tesla didn’t invent alternating current to electrocute the criminal population of the United States, but it is actually the most efficient way to conduct electricity. The problem is that diodes like their electrons to be travelling in a single direction and not dancing backwards and forwards like someone doing the tango. So LEDs require a power pack, which has probably been put together in some south east Asian shed at a price that is so shockingly low you don’t want to know, just to convert AC to DC. The upshot is that although the LED might be good for seven years, its power pack probably isn’t and this results in LEDs sputtering out. But not with anything exciting like a whiff of smoke or a bang; they just slowly grow dim (although they might appear to blink if you look at them through a viewfinder).

Compare this to that trustworthy light source of yonder year still glowing with all its 4 Watts to light up fire engines on those dark Californian nights. Still a LED will do the same job about 20 pct cheaper.