How bulb makers turned shorter life into a business strategy
In 1924, major lightbulb manufacturers met in Geneva and formed an international cartel later known as Phoebus. Their shared interest was straightforward: a bulb that lasted longer meant customers bought replacements less often. The group agreed to standardize bulbs around a shorter lifespan—roughly 1,000 hours—rather than let manufacturers compete by offering products that kept shining longer.
That agreement made limited durability an engineering target, not merely an unfortunate side effect. Incandescent bulbs produce light by heating a thin filament until it glows. The filament gradually wears out under that heat. Manufacturers can alter its design and operating conditions to trade brightness and efficiency against longevity. A bulb built to meet a fixed lifetime target can therefore be made to fail sooner than one optimized to last as long as possible.
Why coordination made the plan pay
A single company that deliberately sold shorter-lived bulbs risked losing customers to a rival promising longer service. By coordinating across companies, the cartel reduced that competitive pressure. Common standards also made the target easier to monitor: members could test bulbs and penalize producers whose products lasted too long.
The commercial payoff came from repeat purchases. Customers still needed light, but instead of buying a bulb once and using it for years, they returned to the market sooner. The innovation was not simply making a fragile bulb; it was aligning an industry around a product life that encouraged replacement.
The arrangement is often treated as an early emblem of planned obsolescence—the practice of designing products with a limited useful life to sustain sales. It helped make a lasting question visible: when companies decide how durable a product should be, engineering choices can shape not only how well it works, but how often customers have to buy it again.
