A heat sensitive telephone protector module of a type having visual indicator means to indicate the actuation of heat sensitive means upon the occurrence of excessive current flow. The module includes dual heat sensitive units for protecting the tip and ring circuits of an individual subscriber pair, and a single indicator unit which is outwardly projected from the module housing by action of either heat sensitive element.

A central office protector module which includes a light to provide a visual indication whenever the module shorts either of the lines protected by the module to groud as a result of either a sustained overcurrent or overvoltage condition on either line. The module includes a sixth or alarm pin in addition to the two line pins, two equipment pins and one ground pin usually included in the module. The module also includes two internal alarm terminals which are each associated with a respective one of the lines. The light is connected to those terminals and a source of voltage. The alarm terminals are connected to ground to complete the circuit to the light when the associated line is connected to ground within the module.

A protector module (30) for protecting tip and ring conductors of a telepe loop includes a pair of protector assemblies (40--40') which are supported within a common housing (32). A voltage protection subassembly (42) of each protector assembly is connected electrically to a grounding subassembly (44) for causing current associated with excessive voltage surges to be conducted to ground. Each protector assembly also includes a current protection subassembly (41) which comprises a dielectric base, as well as a tubular line pin (61) and a central office pin (57) which are connected together electrically. A shunting element (62) is disposed concentrially about and is supported at one end of the line pin in an initial position by a pellet (70) of a fusible material which extends between a closed end of the shunting element and an edge surface (68) of an open end of the line pin. A spring (43) between a cup (93) of the voltage protection subassembly and the housing maintains the voltage protection subassembly in engagement with the shunting element and the pellet of fusible material in engagement with the line pin. When current flow exceeds a predetermined level that is sufficient to melt the pellet of fusible material or during a prolonged voltage surge, the spring is effective to cause the shunting element to be moved to a position where a flange (67) thereof engages a plate (86) of the grounding subassembly to establish a fault current path to ground.

An externally mounted blown fuse indicator including a housing, a spring-biased plunger, a tungsten restraining wire, two terminals, and a cover, the plunger having a meltable region that is heated by the restraining wire and melts to release the plunger when the fuse blows, the spring engaging a midsection of the plunger, the housing carrying tabs at its ends for engagement with a switch to be activated by the plunger, the spring-biased plunger having greater than 3 ounces force at an extension of 0.11".

A combined transient voltage and sneak current protector is presented. The protector device comprises a two-piece substantially rectangular insulative housing. The housing has four spaced and aligned openings at the bottom thereof for receiving upstanding terminals from a terminal block. The interior of the housing is loaded with four contact members which are adapted to effect electrical connection with a three element surge suppressor (e.g. transistor) and a pair of small cylindrical fuse elements. Each of the four contact members include a female connector communicating with the four aligned openings in the housing. The housing interior also includes a ground contact which electrically connects to the middle element on the surge suppressor. The ground contact passes through a lateral opening in the housing for mating with a novel plug-on grounding bus connector.