In conformity with IEC 60309 standards, all the industrial sockets have a lock or holding mechanism, which keeps the plug firmly locked in the socket, preventing it from being pulled out involontarily.
Sockets with an interlock switch have been designed to meet the safety requirements and, in particular, to prevent plug insertion or removal while the socket is under load.
Their interlocking device allows closure of the main switch and, subsequently, the power supply only when the plug is fully inserted in the socket, and when complete mechanical and electrical connection has occurred between the sleeves and pins.
Plug removal is possible only when the switch is in the "off" position.