A protective switch that disconnects the circuit when it detects current leaking to earth, preventing electric shock in elevator installations.
Full Definition
A residual current device (RCD), also called a ground fault circuit interrupter (GFCI), monitors the current balance between live and neutral conductors. In a healthy circuit the currents are equal; any imbalance indicates current leaking through an unintended path — possibly through a person. When the imbalance exceeds the rated sensitivity (typically 30 mA for personal protection), the RCD trips within milliseconds. In elevator installations RCDs are installed to protect lighting circuits, socket outlets in the pit and machine room, and any circuits where persons might contact live parts. EN 81-20 requires residual current protection for socket outlets within the lift shaft and machine room.
