Why Do Electrical Plugs Have Holes? Unplugging The Mystery

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Why Do Electrical Plugs Have Holes

Electrical plugs are an everyday item we all take for granted, but have you ever wondered why electrical plugs have holes? 

These holes are vital in the safe and effective operation of electrical devices. Understanding their purpose can help you appreciate the careful engineering that goes into even the most mundane of objects, even if not an electrician.

In this post, we will explore the purpose of these holes and why they are an essential part of electrical engineering.

So, why do electrical plugs have holes?

The main reason is to prevent the plug from being accidentally pulled out due to the weight of the cord or plug. This ensures that your electrical device stays connected and powered on. 

Moreover, the bumps on the prongs improve the contact between the plug and the outlet, providing a stable and consistent electrical connection.

Other Reasons Include The Following:

1. Easy connection

In addition to providing a secure grip, the holes in electrical plugs offer an alternative way to supply power to electrical devices. 

If, for some reason, a traditional electrical outlet is not available, the holes can be used to connect the device directly to wires supplying 120V power. 

This can be particularly useful when a power outlet is not readily accessible, such as in outdoor settings or in emergencies. 

The holes in electrical plugs thus serve a dual purpose, highlighting their versatility and usefulness in various settings.

2. To cut production cost

Manufacturers of electrical plugs have a secret trick up their sleeves for cutting costs – the holes in the prongs! 

By incorporating these holes into the design, manufacturers can use a process called punch-out to efficiently produce large quantities of prongs. 

This process leaves behind leftover metal punch-outs, which can be melted down and reused to create another set of prongs. It’s a clever and resourceful way to save on raw materials and reduce waste in mass production. 

3. Safety feature

The holes can also be utilized as a safety lockout feature to prevent dangerous or defective devices from being used. 

The device becomes positively locked out by threading a safety lockout tag through the holes in the prongs, preventing it from being plugged in. 

This ensures that the device cannot be used until the danger tag is physically removed, providing extra safety and protection for individuals working with electrical devices.

You can also use a small padlock and lock the plug to prevent your kids from powering up dangerous machines in the house.

Do All Electrical Plugs Have Holes?

While holes in electrical plugs are not strictly necessary, they are a distinctive feature of Type A and Type B plugs commonly used in the United States and other countries that follow the NEMA standard. Type B plugs have an extra ground pin compared to Type A. 

In contrast, Europe uses circular prongs for their plugs, like the Type E standard in France and the Type F standard, similar to Type E but without a ground pin. 

What Are The Standards For Electrical Plugs?

There are two primary standards for voltage and frequency used in the world. North America uses 110-120 volts at 60 Hz, utilizing plugs A and B, while Europe uses 220-240 volts at 50 Hz, using plugs C through M.

Initially, Thomas Edison selected 110 volts DC for his electric system, but with Nicola Tesla’s assistance, George Westinghouse chose AC instead, recommending 240 V at 60 Hz. 

Despite this, authorities imposed restrictions on the voltage, limiting it to 110 V. Meanwhile, in Europe, AEG, a German company, chose 50 Hz, which aligned well with the metric system’s powers of ten.

Europe initially used the same voltage as North America, i.e., 110-120 V, but after World War II, regulators increased it to 220-240 V to decrease the amount of copper utilized for wiring. 

American regulators implemented a split phase 240 V system, which provided 120 V on two live conductors to each household with a single neutral. This saved copper and was also backward-compatible with existing appliances.

Other continents have adopted either of these two voltage standards, with some nations using variations or a mix of standards.

Which Side Of A 2-Prong Plug Is Positive?

A 2-prong plug has no positive or negative side because of the A/C current. It only has two prongs, one of which is the “hot” wire, and the other is the neutral wire. 

The hot wire carries the current from the source to the device, while the neutral wire returns the circuit to the source. The orientation of the plug does not affect the polarity of the wires.

Can I Use A Plug Without A Hole?

As per the regulations established by the American National Standards Institute (ANSI) and the National Electrical Manufacturers Association (NEMA), the holes are deemed “optional” and solely intended for manufacturing purposes. So yes, you can use a plug without holes.

Why Are Plugs Polarized?

A 110V circuit utilizes polarized outlets and plugs to enhance safety in North America. 

Their purpose is to ensure the completion of the electric circuit by keeping the hot-wired pin on the corresponding side of the outlet and the neutral side and pin on the other. Besides, certain devices necessitate the use of polarized plugs to function correctly.


Why do electrical plugs have holes? The holes in electrical plugs ensure the safe and efficient transfer of electricity from the power source to the device being used.

The design and function of electrical plugs may seem simple, but they result from careful engineering. 

As technology advances, we may see new and innovative designs for electrical plugs and outlets that further improve the current standard. 

However, the basic principles that govern the function of electrical plugs and the holes within them will likely remain the same for many years.

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