In this video from Silver Cymbal on YouTube, we get the full story behind the design choice of holes on electric plugs.
Why do electric plugs have holes? You have seen them for years but what do they do? Stop believing the myths & learn what they do for yourself. After receiving multiple comments asking me to answer this question I hope you enjoy this video.
Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7:30pm ET! To join, head over to YouTube and check out the show’s live chat and our Discord!
Python for Microcontrollers – Adafruit Daily — Python on Microcontrollers Newsletter: A New Arduino MicroPython Package Manager, How-Tos and Much More! #CircuitPython #Python #micropython @ThePSF @Raspberry_Pi
EYE on NPI – Adafruit Daily — EYE on NPI Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey
The holes in the prongs (particularly on US/Canadian plugs) can serve a few purposes. The main purpose is to allow the outlet to firmly grip the plug to prevent it from coming lose and falling out of the socket. This works by having little bumpers installed inside the outlet that line up with and fit inside the holes on the prongs. This keeps the prongs secure inside the outlet, but with enough force the plug can still be removed.
A secondary feature of the holes is that it allows you to wire 120V power directly to the prongs without using a traditional electrical outlet. If you, for some reason, needed to supply power to the appliance via direct wires, these holes would make the job a lot easier by allowing you to connect the wires directly to the prongs.
Finally, you can apply a bar or locking device through the prongs as a safety feature to prevent a device from being plugged into an outlet (e.g. as a child safety precaution or to prevent people from plugging in a device that is malfunctioning).
From Reddit:
The holes in the prongs (particularly on US/Canadian plugs) can serve a few purposes. The main purpose is to allow the outlet to firmly grip the plug to prevent it from coming lose and falling out of the socket. This works by having little bumpers installed inside the outlet that line up with and fit inside the holes on the prongs. This keeps the prongs secure inside the outlet, but with enough force the plug can still be removed.
A secondary feature of the holes is that it allows you to wire 120V power directly to the prongs without using a traditional electrical outlet. If you, for some reason, needed to supply power to the appliance via direct wires, these holes would make the job a lot easier by allowing you to connect the wires directly to the prongs.
Finally, you can apply a bar or locking device through the prongs as a safety feature to prevent a device from being plugged into an outlet (e.g. as a child safety precaution or to prevent people from plugging in a device that is malfunctioning).