Why every electrical outlet now has a grounding pin
A metal pin is now present in nearly every electrical outlet. But do you know why it is there? Below, we explain its application.
5 June 2024 08:19
Electrical outlets vary depending on the country. In Poland, type E outlets (CEE 7/5) are most commonly used. These outlets are also popular in Belgium, the Czech Republic, France, and Slovakia. They have two holes—for the phase and neutral wires—and a metal pin. The latter is particularly important from a safety perspective.
How does an electrical outlet work?
Inside outlets, there are spring-loaded metal contacts that connect with the electrical grid wires. When a plug is inserted into the outlet, its contacts touch the pins in the plug, allowing the current to flow between them. Within the outlet, there is a potential difference, called voltage. Once the plug is inserted, the current flows from the phase wire to the neutral wire, supplying electrical energy to the connected device.
Why do outlets have two holes? This is related to the principle of conserving electric charge. The charge cannot be destroyed; it must accumulate somewhere or be discharged. If the outlet had only one hole, the electric charge would accumulate on the device, leading to potential equalization and stopping the current flow.
What does the metal pin provide?
So why is the metal pin in the outlet so important? Its main function is to protect users. In the event of a failure where the device casing unintentionally connects with the phase wire, the lack of a metal pin could lead to a dangerous electric shock.
"Current always flows through the path of least electrical resistance, and the resistance of the cable is much lower than the human body's resistance. Therefore, the current usually flows through the ground instead of the body, which additionally activates electrical protections," emphasizes the "Ask a Physicist" website.
The main functions of the metal pin in electrical outlets are:
- Protection against electric shock. The grounding pin, connected to the ground, discharges the current in case of failure, protecting users.
- Voltage stabilization. Grounding helps to stabilize the voltage in the system, which is crucial for preventing surges and spikes and helps protect devices.
- Increasing the effectiveness of protective systems. Grounding works with protective systems, such as residual current devices (RCDs), which detect abnormal current circuits and quickly disconnect the power, preventing damage and hazards. The metal pin is particularly important for high-power devices or those located in damp areas with higher risk of shock.
