Why every electrical outlet in Europe has a metal pin for safety

Electrical outlets differ depending on the country. In some European countries, type E outlets (CEE 7/5) are most commonly used, especially popular in Belgium, the Czech Republic, France, and Slovakia. These outlets have two holes – for the phase and neutral wires – and a metal pin. The latter is particularly important from a safety perspective.

Inside outlets, spring-loaded metal contacts 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, quickly leading to potential equalization and stoppage of the current flow.

So why is the metal pin in the outlet so important? Its primary 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 dangerous electric shock.

"Current always flows through the path of least electrical resistance, and the resistance of the cable is much lower than the resistance of the human body. Therefore, the current usually flows through the ground instead of the body, which additionally activates electrical protections," emphasizes the expert form University of Warsaw.

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 stabilisation. Grounding helps stabilise the system's voltage, which is crucial for preventing surges and spikes and protecting 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 essential for high-power devices or those in damp areas with a higher risk of shock.