In many older homes, especially those built without overhead lighting, a wall switch often controls one electrical outlet instead of a ceiling fixture. This allows you to plug in a floor or table lamp and turn it on or off with the switch. To help identify these switch-controlled outlets, some electricians install them upside down, placing the grounding hole at the top. In many cases, only one socket is connected to the switch, while the other remains powered continuously for devices like clocks, chargers, or internet equipment.

However, an upside-down outlet doesn’t always mean it’s switch-controlled. The National Electrical Code does not require this installation style, and electricians or homeowners may choose the orientation for different reasons, including personal preference or added safety in certain situations.

The easiest way to determine whether an outlet is controlled by a switch is to plug in a lamp or another small device and test the nearby wall switches. Once you know which outlets are switch-operated, you’ll better understand how they’re intended to be used—and you may avoid thinking an outlet is broken when it’s simply waiting for the correct switch to be turned on.