A series-wired electrical loop that must remain closed for the elevator to run; any safety device opening its contact immediately cuts power to the drive and brake.
Full Definition
The safety circuit (or safety chain) is the single most important electrical system in an elevator. It is a series circuit passing through every mandatory safety device: door interlocks (car and all landings), overspeed governor electrical switch, pit stop switch, car top stop switch, final limit switches, buffer return contacts, and tension sheave switch. If any device opens its contact — due to a fault, over-travel, or maintenance need — the circuit breaks, the drive control de-energises, and the electromagnetic brake clamps simultaneously. EN 81-20 §14 lists all required safety devices and circuit integrity requirements. Bypassing any safety circuit contact without authorisation is a serious safety violation.
