The Model 854 Electric Switch Lock is used to securely lock the hand-throw lever of a hand-operated switch machine or ground-throw switch stand in the normal position. It provides a means of interlocking a manually operated switch with the signal circuits so that the switch may not be operated unless traffic conditions permit, or unless the normally sealed emergency release is operated. This switch lock may be applied to either a right or left hand layout. The Model 854 Switch Lock has a durable cast-construction. The relay is designed to operate at 100 ohms on 8 to 12V dc. If AC operation is required, a transformer and rectifier are required in separate housing.