Incandescent light bulbs

In the period 1840-1880, twenty-two different versions of the incandescent light bulb were invented. In the UK, Joseph Swan invented an incandescent light bulb and in 1880 set up a business installing lightbulbs in homes and landmarks in England. His house was the first to be lit by an electric light bulb. In the US, Thomas Edison set up his own business installing incandescent bulbs of his own invention.

Edison was sued by another US inventor, William Sawyer, who claimed that Edison’s patent for “a filament of carbon of high resistance” was based on the prior art contained in Sawyer’s own patents and was thus invalid. The lawsuit lasted for several years, and a judge eventually ruled that Edison’s patent was valid. To avoid a possible court battle with Joseph Swan, whose British patent had been awarded a year before Edison’s, he and Swan formed a joint company called Ediswan to manufacture and market the invention in Britain.

A scanned image of a page from Thomas Edison’s 1880 patent, with a diagram of an incandescent bulb. Image: Wikimedia, Public Domain.

As time passed, light bulb manufacturers continued to experiment and innovate new, longer-lasting light bulb designs. Soon, some manufacturers began advertising their light bulbs as ‘longer lasting’ or ‘lasts 2500 hours’. Some manufacturers realised that if the trend toward longer-lasting bulbs continued they would see decreasing sales, since people would not need to replace their lightbulbs very often. They could save themselves and even increase their profits by deliberately limiting the life of their lightbulbs to 1000 hours – but this would only work if all the lightbulb manufacturers joined in. The lightbulb manufacturers joined together to form a cartel called ‘Phoebus’, which existed from 1924 to 1939. The members of Phoebus signed an agreement to limit the lifetime of their bulbs to 1000 hours. In order to ensure compliance, lightbulbs from the cartel-member manufacturers were tested, and those manufacturers whose bulbs lasted too long were heavily fined.

Glamorous art deco style light bulb ads from the 1920s.  Image source:

Glamorous art deco style light bulb ads from the 1920s. Image source: Kaufmann Mercantile.

Why was Phoebus able to impose fines on its members – what hold did the cartel have over them? Did all lightbulb manufacturers join in willingly, or did Phoebus twist their arms in some way? And does some version of the Phoebus cartel still exist today? There’s no way to know, but it’s interesting to think about. One thing we do know is that over the years many patents for long-lasting lightbulb designs were registered, but none of these led to commercial success. And even in 2012, according to Statistic Brain, incandescent light bulbs – the type still used most commonly today – lasted an average of just 750 hours.

Image source:


Wikipedia: History of the light bulb

Wikipedia: Phoebus cartel

Statistic Brain: Light bulb statistics