The Purpose of the Two Small Holes on a Standard Plug

You may have noticed the small round holes near the ends of many electrical plug prongs and wondered what purpose they serve. Although they look insignificant, these holes are actually the result of intentional and functional design.

Common on standard plugs, especially in North America, the holes play an important role in how plugs interact with wall outlets. They are designed with safety, stability, and efficiency in mind rather than decoration.

One primary function is improving how securely a plug fits into an outlet. Many outlets contain internal spring clips that grip the prongs, and the holes help those clips align and hold more firmly.

A tighter connection prevents plugs from slipping out easily. This reduces power interruptions, limits poor electrical contact, and helps prevent excess heat that can develop from loose connections.

The improved fit also enhances everyday safety. When a plug stays fully inserted, less metal is exposed, lowering the risk of accidental contact—an important benefit in homes with children or frequent activity.

These holes also serve practical purposes during manufacturing. They allow plugs to be held steady during assembly, testing, and shipping, and make it easier to attach labels or security seals.

Though small and often overlooked, the holes in plug prongs demonstrate how thoughtful engineering improves reliability and safety. It’s a subtle reminder that even the simplest designs often serve multiple important functions.