In an electric circuit, interlock switches interrupt the current or divert the current from one conductor to another. Interlock switches are a form of safety device on machinery and industrial equipment that needs a guarding mechanism. When the guard opens, the switch trips and opens the circuit and disrupts the current flow of the circuit. The machinery shuts down if the circuit is interrupted.
An interlock switch is primarily a safety measure. A guard may be interlocked to prevent machine operation when the guard is removed. A control may be interlocked to make it nonoperational if a hazardous condition will result.
Manufacturing and industrial environments use interlock switches in machinery of all types. Interlock switches are also used in the domestic environment, in devices such as automated gates or slam-lock doors.
Interlock switches can be simple electromechanical switches like magnetic or limit switches. They also come in complex varieties with sophisticated interlocking mechanisms in the form of sensors and actuators. Examples of modern interlocking switches are multipole magnetic switches and uniquely shaped key switches.