Jordfejlstrømsafbrydere

Jordfejlstrømsafbrydere, often abbreviated as RCDs (Residual Current Devices) or FI-afbrydere (Fehlersstrom-Schutzschalter), are safety devices designed to protect against electric shock. They work by monitoring the electrical current flowing through a circuit. In a normal circuit, the current flowing out on the live wire is equal to the current returning on the neutral wire.

If a fault occurs, such as a person touching a live wire, some of the current will bypass the normal return path and flow to the ground. This imbalance in current is detected by the jordfejlstrømsafbryder. When the imbalance exceeds a predetermined, very low threshold (typically 30mA for personal protection), the device rapidly interrupts the power supply to the circuit, preventing serious injury.

Jordfejlstrømsafbrydere do not protect against overcurrents or short circuits, which are the functions of circuit breakers or fuses. They are specifically for detecting and mitigating the risk of electric shock caused by earth faults or leakage currents. They are an essential component in modern electrical installations, providing an additional layer of safety beyond traditional protective devices. Installation and maintenance should always be carried out by qualified electricians to ensure proper functioning and compliance with safety standards.