Thermally activated emergency electric switch

Abstract From the Canadian patent

The manually actuatable electric switch has a fusible element which melts on subjection to a predetermined temperature to discontinue the flow of electric current through the switch. The structure is incapable of operation on melting of the fusible element without replacement of the element, thereby preventing accidental reactivation, of the switch prior to termination of the unusual thermal conditions causative of the melting of the element. A manually operable plunger normally used to open and close the switch is mechanically connected to the stem of the switch through the fusible element. Melting of the element severs the mechanical connection between the plunger and the switch.