Abstract: Disclosed are an installation device for air gap arrester and installation method thereof. The installation device includes a handheld pole, a wire clamping mechanism provided at the bottom end of the handheld pole for clamping a split wire, a tray provided on the handheld pole for lifting the arrester, an insulating rope provided on the tray, a fixing rope provided on the handheld pole for temporarily fixing the arrester, and a scale provided on the handheld pole for measuring the distance from the bottom end of the arrester to the bottom end of the handheld pole. The installation device for air gap arrester and installation method thereof have high installation efficiency.

Abstract: An arrangement of stack spark gaps, whereby a stack spark gap has multiple electrodes and insulating elements that are arranged between the electrodes, with a first electrically conductive clamping element and a second electrically conductive clamping element, whereby the two clamping elements are arranged opposite to the front ends of the stack spark gaps, with at least one connecting element, by which the two clamping elements are connected to one another, and with connection elements for electrical connection to the stack spark gaps. A device is provided for holding the stack spark gaps together and having them make contact. Three stack spark gaps are arranged beside one another between the two clamping elements, at least one of which is electrically conductive, and the two clamping elements are connected to one another electrically via the connecting element and are arranged with the spark gaps so as to form a star circuit.

Abstract: An arrangement of stack spark gaps, whereby a stack spark gap has multiple electrodes and insulating elements that are arranged between the electrodes, with a first electrically conductive clamping element and a second electrically conductive clamping element, whereby the two clamping elements are arranged opposite to the front ends of the stack spark gaps, with at least one connecting element, by which the two clamping elements are connected to one another, and with connection elements for electrical connection to the stack spark gaps. A device is provided for holding the stack spark gaps together and having them make contact. Three stack spark gaps are arranged beside one another between the two clamping elements, at least one of which is electrically conductive, and the two clamping elements are connected to one another electrically via the connecting element and are arranged with the spark gaps so as to form a star circuit.

Abstract: A switch module applied for a power supply system is disclosed. The switch module comprises a power switch, an insulating member, a surge absorber and a pyrocondensation belt. The power switch is connected with the power supply system, the insulating member is set on the power switch, the surge absorber is electrically connected with the power switch and adjacent to the power switch, the pyrocondensation belt is connected with the surge absorber and the insulating member. The pyrocondensation belt shrinks with a temperature of the surge absorber. When the insulating member is in the initial state, the insulating member does not affect the power switch. The insulating member makes the power switch off when the shrinkage degree of the pyrocondensation belt develops enough to block the power switch from being on.

Abstract: A switch module having a surge absorber is disclosed. In one embodiment according, the switch module includes a casing having an input terminal, an output terminal and an auxiliary terminal, a switch unit installed in the casing for connecting or disconnecting the input terminal to the output terminal, and a surge absorber installed in the casing and between the output terminal and the auxiliary terminal. Therefore, the switch module is capable of absorbing a voltage spike from the input terminal and thus shielding the circuitry of the switch module from damage.

Abstract: A structure for installing a lightning arrester between the cross arm mounted to the upper end of an electric pole and a power line is disclosed. A dead end clamp, the lightning arrester and an insulation reinforcing insulator are connected in series, an end of the insulation reinforcing insulator is connected to the cross arm by a shackle, a disconnector is connected to the voltage outlet portion of the lightning arrester, a grounding wire for diverting abnormal voltage to the ground is connected to the disconnector, and an insulation cover surrounds the dead end clamp and the voltage inlet portion of the lightning arrester.

Abstract: The junction box according to the invention includes a housing defined by a lower case and an upper case. A busbar substrate disposed within the housing includes a plurality of busbar substrates. The pier assembly is disposed on at least one of the lower case and one of the plurality of busbar substrates. The pier assembly either accommodates another of the plurality of busbar substrates or supports another of the plurality of busbar substrates. In one embodiment, the pier assembly is disposed on the lower case. In another embodiment, the pier assembly is disposed on one of the busbar substrates. In yet another embodiment, the pier assembly is disposed on the upper case. A method for assembling the junction box according to the invention includes providing a pier assembly for positioning a busbar substrate assembly and disposing a busbar substrate of the busbar substrate assembly in the lower case. The busbar substrate either receives the pier assembly therethrough or is supported on the pier assembly.

Abstract: A door-use feed protector and a circuit assembly arranging structure using the same is provided. The door-use feed protector includes a protector body to accommodate a circuit assembly in a curved state in a door and a circuit assembly holding portion provided on an outer wall of the protector body so as to hold a portion of the circuit assembly outside the protector body. The circuit assembly holding portion may be an auxiliary protector. The auxiliary protector has at least a pair of holding walls facing each other. The holding wall is provided with a resilient holding piece or an engagable cover for preventing the circuit assembly from protruding. The circuit assembly is introduced in the protector body of the door-use feed protector, and a portion of the circuit assembly led out of the protector body is held by the circuit assembly holding portion and is arranged toward an auxiliary in the door.

Abstract: A voltage-controlled oscillator including a dielectric resonator having a ferroelectric ceramic material placed between two metallized surfaces and biased by an electric field created by a difference in potential applied between the two surfaces as a function of a tuning frequency of the oscillator. Also included is a load impedance, and an active amplifier element coupled between the dielectric resonator and the load impedance. Further, the ceramic material is formed by metal oxides of the family: Bax;Sr(1-x) Ti(1-y)(A)y O3 (1) in which: A is a constituent configured to reduce dielectric losses of the material, and −0.4≲×≲0.9−0.001≲y≲0.2.

Abstract: A low profile mount for a disc varistor. A thermally sensitive switch is provided both for single and multiple electrode embodiments. The switch may be placed in a shorting circuit and include a spring biased conductor prevented from closure by a heat sensitive element which softens in responsive to excessive heat. The varistor may be fused to prevent excessive current from a short circuited but not open circuited varistor. Methods are also provided.

Abstract: There is provided a surge absorber without chips in which a pair of discharge electrodes arranged facing to each other in a housing 1 are fixed by welding of the housing 1 with a distance between the discharge electrodes maintained. Clean and dry air or a mixed gas mainly comprising such air is sealed in an air chamber 4.

Abstract: A stamp-making apparatus is provided in which a transparent presser plate is arranged such that the presser plate is parallel with a stamp-making object material, an ink ribbon having a stamp image formed thereon is urged against the stamp-making object material via the presser plate, and exposure of the stamp-making object material to light is carried out via the ink ribbon as a mask. A ribbon feeder rolls out an ink ribbon wound around one end portion thereof to a position facing the stamp-making object material, and then rolls up the ink ribbon around another end portion thereof. A relative translation of the presser plate and the stamp-making object material is made toward each other by moving at least one of the presser plate and the stamp-making object material to thereby urge the ink ribbon against the stamp-making object material. A guide guides the ink ribbon when the ink ribbon is fed, to space between the presser plate and the stamp-making object material.

Abstract: A device for connecting, and then isolating and disconnecting an arrester includes a non-conductive housing with two electrical terminals. The housing has opposite ends separated by an internal chamber. The terminals are mounted at the housing ends. A resistor engages and extends between the terminals in the housing internal chamber. A cartridge with an explosive charge is mounted in the internal chamber adjacent the resistor. A gap spacer surrounds the cartridge, is adjacent one of the terminals and is spaced from the other terminal.

Abstract: A current-limiting switch, with current connections and contacts, at least one of which is movable, having an associated drive, for opening the moving contact when a predefined electric current intensity is exceeded, are provided. The drive is a thermoelectric drive where a disk-shaped resistor body is present, in a closed housing made of insulating material, for high-intensity discharges, plurality of resistor bodies and associated electrode disks, acting as contacts, are connected electrically in parallel and mechanically in series in the housing made of an insulating material (1). This results in increased switching capacity with compact design.

Abstract: A miniature overvoltage protection device including a back-up air gap for use in miniature telephone modules and related equipment includes a generally U-shaped bracket adapted to receive an overvoltage protection device thereon and has a bracket insulating member with a dielectric disposed between the overvoltage protection device terminals and the ground provided on a U-shaped bracket in order to provide back-up air gap protection. In addition, it may include a thermally sensitive material to insulate the overvoltage protection device from the grounding bracket which is activated upon excessive heat occurring in the overvoltage protection device.

Abstract: A flange, which is integrally formed with the inner surface of the cylindrical member, is located at an intermediate point between the end surface position of the cylindrical member to which the electrode plate of one of the discharge electrodes is sealed and the tip position of the discharge electrode portion of that electrode. Both end surfaces of the cylindrical member are hermetically attached with the discharge electrodes. This arrangement prevents inner flashovers without affecting the discharge characteristics of the discharge tube and also ensures manufacture of discharge tubes with no possibility of gas leakage with very high yields even if the machining precision is not so high.

Abstract: The discharge tube of this invention does not employ special shapes of electrodes that are difficult to manufacture, but can still provide a uniform electric field. The electrodes are disposed in the inwardly drawn portions of the cylindrical body in such a way that the opposing front end surfaces of the electrodes are recessed from the inner surfaces of the inwardly drawn portions in a direction that they move away from each other. The discharge electrodes therefore do not project into the inner space of the cylindrical body but are enclosed by the inwardly drawn portions so that they are protected against influences of external electric fields from outside the discharge tube, thus assuring stable and reliable discharges.

Abstract: A breaker assembly for use in conjunction with a surge or lightning arrestor of the type that includes at least one varistor. The varistor circuit is enclosed within a substantially airtight housing that includes a hinged panel. A cantilevered arm is fixed to the hinged panel and includes, adjacent its free end, an aperture for interlocking a post. A conductive disk is fixed to the post and positioned vertically with respect to conductive arms to complete a circuit that includes the surge arrestor. The action of upper and lower springs, in conjunction with the post, serves to close or open such circuit. The position of the post is locked by the interaction of a notch therein with the cantilevered arm so that the opening and closing of the breaker switch is regulated by the attitude of the front panel of the housing that is, in turn, responsive to varistor-generated vapor pressure therein.

Abstract: A microgap type surge absorber comprises a columnar insulator element being covered with a conductive material and provided with a microgap around the center thereof, a pair of conductive caps being fixed on the both ends of the element, first and second electrodes being attached to the both caps, first and second glass tubes adhering to the periphery of the first and second electrodes and surrounding the end parts of the element, and a cylindrical third electrode being held between the both glass tubes and adjacently surrounding the element containing the microgap. The first, second, and third electrodes and glass tubes are charged with inert gas. When a glow discharge started from near the microgap extends to the conductive coating and arrives at the caps, an arc discharge is formed between caps through the third electrode. The third electrode protects the microgap from arc discharge current.

Abstract: An overload protector for a telecommunications system with an overcurrent protection device for each signal line in a chamber formed between a housing and a base and in which the base carries the line and ground pins and also an overvoltage device for each pair of the signal pins, the overvoltage device disposed at the base. In one construction, each overvoltage device comprises a solid state semi-voltage surge protection device at the base and a ground conductor extends laterally of the base between the ground pin and the device.

Abstract: A device for connecting and then isolating and disconnecting an arrester has a first electrical terminal, a second electrical terminal and first and second circuits for electrically connecting the first and second terminals. The first circuit includes a conductive casing mechanically coupled to the first and second terminals and a spark gap located between the outside of the casing and second terminal. The second circuit includes an interrupting mechanism for automatically interrupting connection between the first and second terminals.

Abstract: A line protector for a communications circuit. The protector has a three electrode gas tube, the end electrodes of which are connected to the protector's line input terminals. The middle electrode of the tube is connected to the protector's ground terminal. Decoupling devices such as positive temperature coefficient resistors are connected in series between the line input terminals and the protector's equipment terminals. The protector also includes an additional overvoltage arrestor in the form of two diodes connected between the protector's ground terminal and the equipment terminals. The diodes have a lower voltage rating than the gas tube. A conductive clip which is in firm engagement with the protector's ground terminal is used to removably hold the diodes.

Abstract: A thermal protection device for overvoltage suppressor which includes spaced contacts 6 mounted in overvoltage suppressor magazines 11 of communication systems. A bow-type spring 3 and a melt element 2 l are arranged with the overvoltage suppressor which is mounted in a chamber of a case body or housing 13. The melt element is pierced by at least one arm of the bow-type spring when an overvoltage occurs for short-circuiting the two contacts of the overvoltage suppressor. A thermal protection device with simple components prevents creepage currents between the bow-type spring and the contacts of the overvoltage suppressor 6, a chamber for the overvoltage suppressor is adjacent and abutting to a separate chamber formed in the case body for accommodating a bow-type spring. Between the two chambers there is a separating wall comprising a thermoplastic melt element.

Abstract: A surge arrester disconnecting device which includes a fixed electrode, a movable electrode, and a latch device for holding the two electrodes in engagement. A trigger device, associated with a first spring and a fusible wire stretched between the movable electrode and the trigger device, releases the latch when the fusible wire is melted by continuation current therethrough. Upon trigger actuation and latch release, a second spring assists in the non-explosive disconnection of the movable electrode.

Abstract: A connecting apparatus includes a connecting conductor for connecting a supporting insulator supporting an overhead transmission line and a lightning arrester through a disconnecting member. The connecting conductor includes at least first and second conductor segments having given lengths. The first conductor segment connected to the lightning arrester is greater in bending strength than the second conductor segment connected to the disconnecting member.

Abstract: Electrical distribution apparatus, such as a pad-mounted electrical distribution transformer, including an electrically grounded tank, an electrical element in the tank, and a draw-out surge arrester assembly which extends into the tank. The draw-out surge arrester assembly includes a housing, and a draw-out device removably disposed in the housing. The draw-out device includes a fuse connected in series with the surge arrester, between the electrical element and grounded tank, with the fuse being sized to isolate the surge arrester from the electrical element, should the surge arrester fail to recover properly from a voltage surge.

Abstract: A male base subscriber pair protector module in which substantially all of the internal components thereof are assembled upon an axially elongated base element prior to insertion within a module housing, thereby facilitating manufacture and allowing the use of a wide variety of existing components which are readily adapted for such assembly.

Abstract: A protector for telephone systems and similar systems is in the form of an elongate housing formed by two hollow box-like members, one fitting within the other. In the bottom member, a line terminal is provided at each end, each terminal connected to a line contact member in the housing. A ground terminal is provided at a mid position in the bottom member, connected to a support and ground member. A protector device assembly is mounted in the support and ground member, providing a breakdown gap connected between each line contact member and the ground. The device assembly can be two-electrode gas tube devices, a three-electrode gas tube device, or other devices. Back-up protector devices are positioned between each line contact member and the support and ground member.

Abstract: In response to spurious signals in a circuit connecting telecommunications equipment with a serving central office, the signals will pass through terminals of a protector module and through a protector unit inserted in the circuit causing a lead pellet to melt or the air gap between carbon blocks to short and establish a path to ground so that the spurious signals may be grounded. When the protector unit is removed from the protector module, the circuit remains grounded until the protector unit is replaced. Alternatively, when the protector unit is removed, the electrical path of the circuit is opened by introducing an insulator in the path of signals between the terminals. In one embodiment, in the open circuit condition, unusually high voltages arc over from the protector terminals to a metallic pin and then to ground.

Abstract: An improved telephone protector module for individual subscriber circuits of generally planar configuration, and having heat-sensitive means employing a solder pellet which, upon melting, flows through capillary action to effect a shorting to ground. Secondary air gap means is provided by spacing a pair of conductive parts using a thin insulative wafer having openings therein forming an interruption in the insulation.

Abstract: A subscriber pair protector module of gas tube type in which the heat coil assembly is supplemented by the provision of a planar fusible member placed in direct contact with the gas tube elements to provide a heat sink for a limited period of time to protect the module until the heat coil assembly becomes operative, thereby preventing damage to the synthetic resinous housing element of the module which would interfere with its subsequent removal. An improved gas tube element is also disclosed having recesses disposed in the end surfaces thereof to prevent total shorting action by the heat coil element until the planar fusible member has melted. An improved gas tube element is also disclosed having recesses disposed in the end surfaces thereof to prevent total shorting action by the heat coil element until the planar fusible member has melted.

Abstract: A low voltage valve type arrester device for connection between a domestic electric supply line and earth includes a varistor, a switching device and an encapsulated gas discharge voltage arrester connected in series. The switching device includes two switch members connected together by a solder connection and biased apart by a spring. A fusible link is connected to the two switch members in parallel with the solder connection. When a voltage surge occurs, current flows through the arrester to earth. If the surge is large enough to render the gas discharge arrester continuously conductive, the solder connection melts due to the heat dissipated in the varistor and the two switch members move rapidly apart. The fusible connection rapidly melts by which time the switch members are sufficiently far apart for no arc to form between them.

Abstract: Overload by-pass conductor with an external short circuit heat conduction path, including an outer wall of the overload by-pass conductor, two electrodes, one of the electrodes being a counter electrode, a contact surface connected to the counter electrode, a metal carrier being disposed along the outer wall and being electrically conductingly connected to one of the electrodes, and a solder piece being in a mechanically fixed connection with the metal carrier and being adjacent the contact surface, the solder piece being spaced from other parts of the overload by-pass conductor in an operating state, and the solder piece being deformable for causing an external short circuit upon the occurrence of an overload, the external short circuit being triggered after a delay with respect to the beginning of the overload due to the heat conduction path.

Abstract: A replacement type gas tube protector for use with an older type telephone protector block utilizing a bayonet lug type engagement. The original carbon block protection is replaced by a gas tube element of smaller dimension, a conductive washer, and an insulative washer having a conductive sleeve. The conductive washer and gas tube element form a primary air gap means. The conductive washer and the insulative washer form a secondary air gap means.

Abstract: A protector module (30) for protecting tip and ring conductors of a telephone 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 electrially 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 and a line pin (61) and a central office pin (57) with the line and central office pins being connected together electrically to establish electrical contact between a conductor of the circuit and its protector assembly. A shunting element (62) is disposed concentrically about the line pin and is releasably secured to one end of the line pin in an initial position by a fusible bonding material.

Abstract: An overvoltage surge protector and housing for telephone communication lines to protect equipment connected thereto includes an insulated housing having one terminal disposed therein which is adapted to be connected to earth ground and a second terminal disposed in a removable assembly which includes the means for connection to the communication line as an integral part thereof. The overvoltage surge protector device is adapted to be retained within the second terminal and, when removed for replacement by a service technician, requires that the communication line affixed to the terminal be removed from the terminal in order to remove the protector device, thus requiring the communication lines to be reconnected when the defective protective device is removed and/or replaced.

Abstract: A protector unit (30) for protecting tip-and-ring conductors of a telephone loop includes a pair of protector assemblies (40-40') which are supported within a common housing 932). A voltage protection subassembly (42) is connected electrically to a ground subassembly (44) for causing current associated with excessive voltage surges to be conducted to ground. Each protector assembly includes a heat coil subassembly (50) mounted on a dielectric half-base (51), together with a central office pin (57). The heat coil subassembly includes a line pin (61), an eyelet (62), disposed concentrically about the line pin and releasably secured to one end of the line pin in an initial position by a fusible bonding material, and a resistance wire (69), wound about the hub of the eyelet. One end of the wire is welded to the eyelet, and the other end is welded to the central office pin to establish a direct current path between the line pin and the central office pin.

Abstract: A miniature surge protector for use in telephone central offices, or the like which are provided with terminal blocks for communication lines includes an in-line over-current coil arrangement which grounds each communication line if an overcurrent flows therethrough and is additionally provided with a gas tube surge protector and an auxiliary air gap disposed across a pair of communication lines and a common ground terminal, thus providing overvoltage and overcurrent protection to a pair of telephone communication lines.

Abstract: A line protector for central office use comprises an elongated housing open at one side for receiving components and a cover for the opening. First and second surge arresters are coaxially positioned within the housing. First and second line terminals are respectively connected to the arresters as is a common ground terminal. The three terminals project from one end of the housing in the provision of coplanar flat pins for plug-in connection with a circuit board edge connector. Means including a test contact in the housing permits use of a test probe to test the lines while the protector is plugged into the connector. A shiftable insulator in the housing is used optionally to interrupt the inside lines at the line terminal pins.

Abstract: The subject-matter of the present invention is a plug-in connector with arresters (1) for separating blocks, comprising a cartridge-type housing (20) of insulating material having receptacles for the arresters (1), each of said arresters being connected through a respective fuse element (11) and an earth contact (3) to an earth strip (7) and being exchangeably retained within the receptacle by means of compression springs (10). In order to obtain a number of advantages with respect to manufacture and operation, such as simple construction and inexpensive manufacture as well as easy manipulation and suitability for two respective tapping contacts per arrester, in the plug-in connector according to the invention the arresters (1) each comprise three electrodes (12, 12', 12") each of which is connected to a contact pin (c, b, a) both mechanically and electrically.

Abstract: A gas tube overvoltage protector has two opposed electrodes sealed in a tubular dielectric housing, the outer ends of the electrodes extending from the housing. The inner ends of the electrodes define a primary gap at sub-atmospheric pressure. The lower electrode has an extension of reduced diameter on its outer end. An auxiliary gap is formed by pushing on a metal cap over the lower end of the dielectric housing, with a thin flexible dielectric member between the cap and the outer end of the bottom electrode, the extension extending through the dielectric member and cap. One or more apertures in the thin dielectric member define the auxiliary gap, between metal cap and bottom electrode. A further feature is that the cage, within which the protector is positioned, has one or more legs preformed such that their lower ends are pushed into positive contact with the metal cap when assembled into a closed ended hollow cap for assembly into a protector block.

Abstract: An improved gas type telephone protector module in which the firing of a heat-sensitive means causes a slidably mounted ground plate to bypass in both circuits to the flow of excess current and/or voltage surges to ground. Means are incorporated to provide a secondary air gap which becomes operative upon the failure of either chamber of the gas tube.

Abstract: A clip-on device to protect telephones and communication apparatus, wherein clips for releasably holding a 3-terminal gas protector are external extensions of electrically insulated spaced terminals within the housing. A heat coil in series with each communication line and a carbon block air gap protector across each half of the gas protector for redundancy, are within the housing. The heat coil protects against a sustained overcurrent condition on the line while the gas and air gap protectors ground over-voltages of short duration. Utilizing heat conduction means, heat generated from sustained over-voltage melts a fusible disc allowing spring biased parts within the housing to move and short line terminals to ground.

Abstract: A lightweight frame having a base of non-conducting material and end frame members consisting of aluminum mounts a pair of clip-type fuse supports. Each fuse support is attached to connectors which extend through the housing for connection to the lead in and ground lines of a radio, television, or like antenna. A plastic cover snaps in place over the base and ends to allow the user to view the condition of the fuses.

Abstract: 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.

Abstract: An electrical surge arrester module having a back-up external spark gap in its base assembly comprising an insulator plate perforated at points intermediate a terminal contact surface in said base assembly and a conductive plate at ground potential when said surge arrester module is in use.

Abstract: A clip-on device for use with an over-voltage protector to protect telephones and other sensitive apparatus. The device comprises a housing in which is disposed in electrically insulated spaced array, electrical contact means and heat conduction means. Each of these means have portion external to the housing which detachably grasps the over-voltage protector. Movable elements disposed within the housing include electrically insulating fusible spacers. The housing clips onto the over-voltage protector and engages the respective electrodes thereof. A sustained overload condition causes the fusible spacers to fuse whereupon the movable elements operate to short the electrical contact means to ground.

Abstract: A line protector has a housing with coaxial surge voltage arresters, line terminals and a ground terminal. One line terminal is substantially at one end of the cavity of the housing while the other line terminal extends substantially the full length of the cavity of the housing. The ground terminal extends from between the arresters to said one end of the housing cavity. Each terminal projects from the housing at said one end. The three terminals are insultated from the arresters by barrier walls in the housing. A cover closes a side opening in the housing through which the components of the protector are inserted.

Abstract: A secondary valve arrester for protection of secondary electrical systems, comprises a housing having a lid and base portion, the latter of which includes a plurality of compartments each of which is dimensioned to receive a valve block and spark gap assembly or a varistor assembly; the number of said assemblies included in the arrester corresponding to the number of phases protected in the system. Each said assembly includes connecting electrodes of similar construction, each connecting electrode having two offset male terminals and one offset female terminal for connection to externally connected lead wires or other connecting electrodes. The housing lid includes first and second rib sets for extension into the base portion to retain the said assemblies in a tightly stacked condition in respective compartments.

Abstract: A clip-on device to protect telephones and communication apparatus, wherein clips for releasably holding a 3-terminal gas protector are external extensions of electrically insulated spaced terminals within the housing. A heat coil in series with each communication line and a carbon block air gap protector across each half of the gas protector for redundancy, are within the housing. The heat coil protects against a sustained overcurrent condition on the line while the gas and air gap protectors ground over-voltages of short duration. Utilizing heat conduction means, heat generated from sustained over-voltage melts a fusible disc allowing spring biased parts within the housing to move and short line terminals to ground.