The light bulb the cartel wanted to replace
The product was the incandescent light bulb. In the 1920s, major lamp makers in the Phoebus cartel coordinated around a standard bulb life of about 1,000 hours. The agreement was more than a shared recommendation: members monitored products and could penalize companies whose bulbs lasted too long or too briefly.
That helped limit competition over durability. A company that sold bulbs lasting much longer could give customers fewer reasons to buy replacements—and undercut the cartel’s common standard.
Why a longer-lasting bulb was possible
An incandescent bulb makes light by sending electricity through a thin tungsten wire, called a filament, until it glows. The filament gradually wears away under heat. Makers can extend its life by running it less hot, but that also makes it produce less light for the electricity it uses. Running it hotter produces brighter, more efficient light, but wears the filament out sooner.
So the cartel’s target did not mean every longer-lived bulb was automatically better in every respect. It meant manufacturers had a coordinated limit on a feature—how long a bulb could last—that might otherwise have been used to attract customers. The striking part is that the replacement cycle was shaped not just by the technology, but by an agreement among the companies selling it.
