Translations:Residual current device/2/en

A residual current device (RCD) or Ground Fault Circuit Interruptor (GFCI) is a device that constantly measures the current flowing between the outgoing and incoming wires of a circuit to see if there is a difference. If there is a difference, it means that there is a fault at some point in the circuit and a potential hazard. A RCD is typically incorporated into a breaker or outlet so that it is able to disconnect the circuit upon identifying a difference in current or fault. RCDs are often required by the electrical codes in many countries. In a grounded system this current is typically returning through the grounding system. RCDs are far more effective at preventing electrical accidents than OCPDs as they are far more sensitive and can therefore identify hazards more easily. All RCDs should include a test button (pictured in yellow in the diagram) that enables users to periodically make sure the device is functioning correctly.