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Have You Ever Wondered Why Electrical Plugs Have Holes?

Holes in Electrical Plugs

If you’ve ever looked at an electrical plug, you may have noticed that there are two (or sometimes three) holes in the top of it. If you’re like most people, you probably haven’t given it much thought. But have you ever wondered why those holes are there? Keep reading to find out!

The Origins of the Electrical Plug

The first electrical plug was invented by Benjamin Franklin in 1752. At the time, plugs were made of copper and brass and did not have any holes. It wasn’t until 1881 that an electrician named Henry Howell patented a design for a plug with two small holes.

Howell’s design was based on a previous invention by George Fellows, who had patented a design for an electrical outlet with two holes in 1875. Fellows’ outlet was designed to prevent people from accidentally electrocuted by mismatched plugs and outlets. When Howell saw Fellows’ invention, he realized that it could be adapted for use with plugs as well.

The Purpose of the Holes in Electrical Plugs

Holes In The Top Of Electrical Plugs Serve An Important Purpose

Those holes actually serve a very important purpose. They’re used to help prevent the electric current from arcing. Arcing is when sparks jump through the air from one conductor to another. When electricity is flowing through a wire, electrons move around the metal conductor in a circle. Sometimes, though, those electrons can jump off of the conductor and into the air.

If there’s enough voltage, an arc can form between two conductors—like the live conductor and the earth conductor in an electrical plug. When an arc forms, it creates heat. If enough heat builds up, it can cause a fire. The holes in an electrical plug help to prevent arcs from forming by providing a path for any arcs that do form to escape.


So there you have it! The next time you look at an electrical plug, you can rest assured knowing that those holes serve a very important purpose. And if you ever find yourself in a situation where sparks are flying from an electrical socket, be sure to unplug the appliance right away and call an electrician—it could be a sign of a serious problem. Thanks for reading!