In an episode of Friends, Monica becomes obsessed with a light switch that, according to Joey, does “nothing.” Monica, convinced that it must control something in the apartment (“They wouldn’t have put it there if it didn’t do something!”), begins an obsessive hunt to uncover what the switch does. Though it’s scarcely more than a silly subplot, Monica’s dilemma exposes an interesting household problem: Every home seems to have a mysterious light switch somewhere—near the back door, next to the porch light, at the basement stairs, along a row in the den. A light switch that does nothing.
The light switch is a lovely, ordinary thing. You can look at one and understand intuitively that the up position means on and the down position means off. The panel sits flush against the wall, elegant in its unobtrusiveness. The placement of light switches is so familiar that in the dark, you can feel around at the standard height (four feet from the ground) until you find the right panel to illuminate an unfamiliar bathroom.
Light switches exemplify familiar design, which, according to Henry Petroski’s Small Things Considered: Why There Is No Perfect Design, is a name for things that are “so predictable in their form and function that we do not give them a second thought.” We haven’t given light switches much thought for nearly a century now. The toggle light switch was patented in 1917, replacing the push-button switch of the late 19th century. Since the toggle’s inception, it has remained the most ubiquitous switch in North America. The 1980s saw the introduction of the rocker, a flat-paneled switch that became popular domestically and throughout Europe and Asia. But the rocker was really just a facelift, a minor aesthetic evolution of the traditional design similar to the shift from push-button to toggle. The light switch has essentially never changed.