Abstract: An electric device is provided as an interface between a permanent power source (e.g., an electric wall outlet) and an electrical appliance for interrupting electrical power to the appliance in the event the temperature of either the power cord plug of the electrical appliance or permanent power source rises above a predetermined temperature. The electric device detachably couples to the electric power terminals of both the permanent power source and electrical appliance and is sensitive to the temperature of the aforementioned terminals. The electric device includes first and second temperature switching elements which are responsive to interrupt electrical power from the permanent power source to the appliance when either of the terminals is of a temperature which equates with a first predetermined temperature determined by the first temperature switching element or a second predetermined temperature determined by the second temperature switching element.

Abstract: In a circuit breaker having a thermal-magnetic trip, the voltage across the bimetal is used to sense load currents. This voltage signal representative of current through the bimetal can be used as an input to an arcing fault detector. The signal is converted to a bandwidth limited di/dt signal. If the magnitude of the di/dt signal exceeds a threshold indicative of the onset of an arc a predetermined number of times within a given interval, the circuit breaker is tripped. The voltage across the bimetal can also be used in other devices requiring a measure of load current such as, for example, a meter or an overcurrent alarm.

Abstract: An overcurrent protection device for a motor M with an overheat prevention function having a housing 10 with fixed contacts 16, 18 and movable contacts 24, 26. A first snap acting bimetallic element 20 in the device is responsive to heat from overcurrent conditions and a second snap acting bimetallic element 40 is responsive to heat from the temperature for the motor M. The movable contacts 24, 26 are controlled by the first bimetallic element to cause engagement or nonengagement with the stationary contacts 16,18. Coupling members 42, 44 contained in the housing engage both bimetallic elements 20, 40 and allow the first overcurrent bimetallic element 20 to snap independently of the second bimetallic element 40 while providing for snap action of the second bimetallic element 40 to also cause the first bimetallic 20 to snap.

Abstract: A combined electrical plug and circuit breaker that interrupts current when excessive current flows. A housing receives a body portion with extending blades. A bi-metallic strip opens silver contacts when an overload occurs. A rod member can reset the contacts when the overload problem is solved.

Abstract: An electrical service installation comprises a plurality of circuit breakers protecting against overcurrent hazards in branch load circuits. An acceleration, bypass circuit is provided for each circuit breaker. Current flow through each of the bypass circuits is controlled by a normally non-conductive SCR. Current flow to each branch circuit passes through a sensing resistor that is connected across the gate and cathode of the associated SCR. When the voltage drop across the sensing resistor reflects a current level indicative of an "arc short circuit", the SCR is triggered to a conductive state. Current then flows through the bypass circuit increasing current flow through the associated circuit breaker, to thereby provide a substantially increased current magnitude for magnetically tripping the circuit breaker. Circuit breakers are thus tripped to provide protection against the hazards of "arc short circuit" currents that do not have a magnitude sufficient to initiate magnetic tripping.

Abstract: An overload protective apparatus has fixed contacts connected to at least one pair of fixed terminals secured on the bottom of a case, a dish-shaped polymetallic element, e.g., a bimetal or trimetal having movable contacts bonded thereon so as to oppose the fixed contacts, and an adjusting bolt supporting a central portion of the polymetallic element for maintaining the polymetallic element at a position separate from the bottom of the case, wherein the polymetallic element and the adjusting bolt are accommodated in the case. The polymetallic element used herein is constructed to make a current density around bonding portions for the movable contacts higher than other regions, such that portions around the movable contacts are more susceptible to rupture when an abnormal current flows through the polymetallic element. The polymetallic element is also constructed to prevent degradation of the spring constant thereof.

Abstract: A starting device for a single phase induction motor can reduce the power consumption and restart in a short time. The starting device for the single phase induction motor having a main winding and a starting winding comprises a starting positive temperature coefficient thermistor connected in series with the starting winding, a bidirectional current control device connected in series with the starting winding and the starting positive temperature coefficient thermistor, and an auxiliary positive characteristic thermistor having a heat capacity smaller than that of the starting positive temperature coefficient thermistor connected in parallel with the starting positive temperature coefficient thermistor, a terminal of the auxiliary positive temperature coefficient thermistor being connected to a gate of the bidirectional current control device.

Abstract: An overcurrent protection device 10 has a fixed 26 and a movable 32 contact electrically connected to a pair of terminals 14, 16 and a snap acting bimetallic member 34 which is responsive to a thermally resistive element 28, connected in series with the contacts between the terminals to cause the contacts to move from an engaged position to a disengaged position. The device further includes a current bypass path 24 adapted to be connected in parallel with the thermally resistive element 28 and a second thermally responsive bimetal member 24 b to cause the electrical connection. Additionally, a heater block 18 can be provided between the terminals 14, 16 which has a resistance significantly higher than that of the thermal resistive element 28.

Abstract: In an auxiliary power unit for a vehicle which comprises a plug to be connected to a cigarette lighter socket provided on the vehicle, and sockets electrically connected to the plug to provide power sources for electrical devices on the vehicle. An overcurrent protective switch is turned off to interrupt the path of current to the sockets when overcurrent flows through the sockets, and a thermally operated member provided for each socket detects the temperature of the socket. When the temperature thus detected exceeds a predetermined upper limit value, the thermally operated member shunts the path of current from the socket, thereby to cause the overcurrent protective switch to operate.

Abstract: A thermal setting process of the bimetal strip consists in securing an adjusting pin to the trip bar by means of laser welding when the bimetal strip reaches a first preset temperature, and then checking tripping at a second temperature with or without action on a positioning screw of the bar.

Abstract: A data-recording machine is protected against temperature overshoots by a device (12) for protecting electrical lines comprising two blister-type thermosensitive elements (10C, 10F) which control series-connected electric contacts (7C, 7F) so as to close the electrical line outside the normal operating range and to prohibit operation even after a return to said range.

Abstract: A thermic protection device for vehicle lighters in which the electric contact holder base (16) is provided with a first bimetallic lamina (15) for thermic protection against superheating that causes a short circuit allowing the lighter to be reutilized.The base (16) is fitted with a second bimetallic lamina (18) for thermic protection that remains abut against the resistor (12) of the lighter's plug (10) when this is pressed into the base, maintaining the electric contact until at least the first lamina (15) is started up.

Abstract: A multipole circuit breaker, for example, a three pole circuit breaker, can detect a condition when less than all of the phases are open circuited to trip the circuit breaker. This reduces the tripping time and hence risk of damage to the electrical load. The circuit breaker includes a thermal trip unit and a phase sensitivity assembly that is interlocked with the bimetals included with the thermal unit. The phase sensitivity assembly includes one or more levers, responsive to the deflection of a bimetal corresponding to the open circuited phase resulting from cooling action of a bimetal relative to the other bimetals. The relative displacement of the cooling bimetal is used to either trip or reduce the tripping time of the circuit breaker.

Abstract: A heat flow detector is described which measures a predetermined rate of heat flow in its surroundings. The surroundings being in the proximity of a recessed incandescent fixture which is designed to operate safely in the designated environment. Should the operating environment change for the fixture it will be sensed by the heat flow detector. If the operating environment becomes more dangerous so that a fire or other damage may occur the heat flow sensor will turn the incandescent lamp off and on at a slow rate to indicate the changed operating environment.The heat flow detector will cause a slow turn off and on if an oversize lamp is inserted in the incandescent fixture. The heat flow detector will then prevent an overheated condition due to an incorrect bulb.

Abstract: A temperature switching device for an electrotechnical part to be protected against an excess temperature due to a fault, with a first bimetallic switch and an ohmic resistor connected in parallel thereto, so that, after opening the bimetallic switch as a result of an excess temperature, the flow of current takes place across the ohmic resistor, which produces heat and as a result the bimetallic switch is kept open even in the case of the cooling of the excess temperature initially triggering the switching process due to a malfunction of the electrotechnical part to be protected, as a result of the evolution of heat of the ohmic resistor. At least the ohmic resistor is connected in series with a further automatically resettable thermal switch having an opening temperature above that of the first thermal switch, but well below temperatures causing irreversible damage to bimetallic elements and the two thermal switches being in close thermal contact.

Abstract: A current interrupting apparatus adapted to be interposed in either a single or multiple phase electrical circuit includes a fuse interposed in each phase of the circuit. A current interrupter is electrically connected in series with each fuse for interrupting the current through the circuit, each current interrupter including a pair of normally closed electrical contacts and structure for opening the pair of contacts in response to a fault current of a magnitude different from the magnitude of current necessary to cause fusing of the fusible element of the fuse. A current interrupter triggering circuit is included in the apparatus for triggering operation of the contact opening structure of all of the current interrupters in response to fusing of the fusible element of any of the fuses to protect the circuit from the effects of single phasing.

Abstract: A 60 VA transformer is described. A recycling circuit breaker mounted on and connected in series with the secondary winding of the transformer preserves the integrity of the transformer and permits its continued use after a short circuit. A thermal fuse mounted on and connected in series with the primary winding provides short circuit protection in the event the circuit breaker fails in a closed position. Achievement of this end is attained by decoupling the transformer windings to reduce short circuit, secondary current flow. Decoupling is provided by spacing the transformer windings a distance of about 0.090 in. A controlled failure mode provides energy limiting protection for the secondary load circuit in the event of circuit breaker failure in the closed position. Controlled failure is provided by the use of secondary insulation which melts within one minute of a short circuit, permitting turns of the secondary winding to short and reduce current flow to eight amp. within the one minute period.

Abstract: An overtemperature protector for an incandescent lamp socket housing comprises a glass enclosed circuit breaker and an electrical heater in proximate heat transfer relationship therewith. The heater is in series with the circuit breaker so that when the circuit breaker is open, there can be no current flow through the heater.

Abstract: A motor protector includes a case having an open end, a terminal plate secured to the case and having a pair of fixed contacts, a disc-shaped bimetal supported in the case and having a pair of movable contacts engaged with and disengaged from the fixed contacts respectively, a temperature-sensitive switch disposed so as to close the open end of the case and sensing the temperature of a sensed object to be turned on when the temperature thereof reaches a predetermined value, and a heater disposed in the vicinity of the bimetal and connected in series to the temperature-sensitive switch.

Abstract: Protective circuits for preventing fires due to arc short circuits (as opposed to dead short circuits), are described. Current flow in excess of that existing during normal transient overloads is indicative of an arc short circuit. Protection is provided by triacs which are triggered by circuit current flow in excess of that existing during normal transient overloads. When triggered, the triacs, in series with the fuse or circuit breaker, are placed directly across the power source and thus actuated substantially instantaneously to interrupt current flow to the load circuit. By thus interrupting current flow the hazard of a fire is obviated. Means are also provided for giving a visual indicium that the protective circuit has been actuated by triggering of the triacs. Additional means are provided for triggering the triacs in response to an overheated main electrical service connection.

Abstract: An overtemperature protector for an incandescent lamp socket housing comprises a glass enclosed circuit breaker and an electrical heater in proximate heat transfer relationship therewith. The heater is in series with the circuit breaker so that when the circuit breaker is open, there can be no current flow through the heater.

Abstract: A controlled cycling thermal protector device is provided comprising a snap blade and a PTC resistive heater disposed outside of a bulbous envelope in which the snap blade thermal protector is housed. The snap blade thermal protector and the resistive PTC heater are wired and constructed so as to prevent cycling of the snap blade thermal protector. The PTC heater is disposed upon a sleeve which encircles the bulbous envelope so as to radiate heat onto the snap blade thermal protector to keep it open once the circuit has been broken.

Abstract: A changeover contact-making apparatus with interlocking member and module of protection protected against overcurrents is provided. In a same case, two contact-making systems and coil switches are disposed on each side of a median plane PP' in which the interlocking member is placed. In one of the case inner volumes defined by the plane PP' are placed a single protection module, a tripping mechanism and the respective connection terminals.

Abstract: A wound bobbin coil (A) and a fuse (B) are interconnected electrically in series. The coil and the fuse are mounted closely adjacent and molded into a tough, nylon encapsulation (C). The series connected coil and fuse are connected with electrical terminals (26, 30) to form a unitary electrical component which is readily connected with associated circuitry. In this manner, when the coil becomes damaged sufficiently to blow the fuse, both the coil and the fuse must be replaced. A repairman cannot short the fuse or merely replace the fuse and allows a damaged coil to continue functioning. In the preferred utilization of the present coil in a freezer compartment ice maker, coil failures can cause flooding, overheating, and other catastrophic damage to a refrigerator/freezer.

Abstract: A terminal block and overload protector for a compressor assembly for connection to the terminal pin assembly of a compressor located on the inside wall of a compressor casing. The assembly includes a housing with three apertures therein into which three of the terminal pins are disposed. Electrical connector clips are disposed in the housing for connection to the terminal pins. The housing also includes a space in which a motor protector is secured. The motor protector has two terminal pins which are secured to slip-on quick-connect terminals. The motor protector housing has a third connector clip secured thereto. Each of the three connector clips has a knurled inside surface for gripping and retaining of the respective terminal pins.

Abstract: A thermal protection device for a dual input voltage lighting fixture apparatus which includes a reversible connector for coupling either of two possible input voltages to the appropriate terminal of a winding of a transformer/ballast apparatus via a normally closed contact of a heat responsive thermal switch having a heating element electrically coupled to the reversible connector and thermally coupled to the closed contact. The latter contact opens in response to a level of heat above a given value. The transformer winding has two connection terminals, one of which is a tap point, connected to the reversible connector. The connection scheme provides the same energizing voltage to the heating element for each of the two different possible levels of the input voltage. The apparatus will automatically indicate if the connector is reverse connected for either of the two input voltages.

Abstract: A light responsive control and overload protection circuit for low voltage illumination systems includes means responsive to ambient light for providing an enabling output. Control means respond to the enabling output for switching heating current on when enabled. Heat-producing means is provided. The heating current passes through the heat-producing means whenever the control means is enabled. Heat-responsive circuit breaker means are in circuit between a low voltage power source and the load. The heat-producing means is thermally coupled to the heat-responsive circuit breaker means to transfer heat thereto and effect and maintain an opening thereof whenever sufficient ambient light is present. Heat-responsive means respond to heat from the heat-producing means to prevent the overheating thereof during overloads and load circuit short circuiting.

Abstract: A safety connector providing an overcurrent protective element, an overvoltage protective element and bimetal connecting terminals, in which the overcurrent protective element includes an upper terminal and lower terminal on the upper and lower part of the body, and which includes bimetal connecting terminals within the body, and a heating coil connected to the upper terminal and to a bimetal connecting terminal. Another bimetal connecting terminal is connected to the lower terminal. An overvoltage protective element is mounted on the bimetal connecting terminals on the electrodes and grounding electrode, respectively, and leading ends of the bimetal connecting terminals are placed to face each other.

Abstract: This invention relates to a compact protector which is used to prevent the over-heat of a compact motor used in heat generating appliances such as a hair dryer or electric washing machine. The protector incorporates therein an excess current prevention portion utilizing a bimetal and an excessive temperature rise prevention portion utilizing a temperature fuse. The protector opens an electric path by the double safety devices.

Abstract: A motor protector having a thermostat metal element thermally coupled to an electrical motor in a refrigerator compressor motor system has a heater responsive to motor current thermally coupled to the thermostat metal element and has an improved component arrangement to provide locked rotor and ultimate trip protection for the motor without requiring calibration of the operating temperature for the protector after assembly or after incorporation in the motor system.

Abstract: A motor protector having a thermostat metal element thermally coupled to an electrical motor in a refrigerator compressor motor system has a heater responsive to motor current thermally coupled to the thermostat metal element and has an improved component arrangement to provide locked rotor and ultimate trip protection for the motor without requiring calibration of the operating temperature for the protector after assembly or after incorporation in the motor system.

Abstract: A safety device for protecting communications equipment that is coupled to a communications line. The device includes a safety connector having overcurrent and overvoltage protection means therein for connecting the communications line to ground upon occurrence of an overcurrent or overvoltage on the line. The safety device includes a housing and receptacles for connecting to input and output terminals of the communications line and to a ground terminal, wherein the terminals are on a terminal stand that serves many communications lines and receives many safety devices thereon. The overcurrent protection means employs a bimetal element that is heated by a heating coil connected in the communication's line. The overvoltage protection means includes a gas discharge tube which also may include bimetal elements.

Abstract: A PTC starter that is electrically connected to an asynchronous motor by pins that extend through holes into the starter housing, which includes an open top, generally box shaped base portion and a cover having a downwardly opening recess mountable on the base portion. Support structure is provided in the base portion for loosely retaining a disc shaped PTC resistor and a pair of contact members on opposite sides of the resistor in a loose stacked relationship with the resistor, the support structure including a base portion receptacle for loosely retaining an electrical terminal bushing portion adjacent to a contact member. The cover in having its recessed portion moved downwardly along the contact members and resistor result in the contact members being resilient retained in electrical engagement with the resistor electrode surfaces, and at least two terminals extending upwardly through the cover. Advantageously the housing mounts a thermal protective switch for the motor.

Abstract: The motor protection switch comprises a movable contact piece being manually movable by way of an actuator, which includes actuator buttons. The contact piece can be brought in and out of contact with a resting contact piece. The motor protection switch can also be released by overload current or short circuit current. A retracting or pullback mechanism with two settings settable from outside are provided for the actuator. In the first setting the pullback mechanism will hold the actuator in a trip position between the "on" and the "off" position after overload tripping or short circuit tripping has occurred. In the second setting the pullback mechanism will allow direct movement of the actuator from said "on" position into said "off" position after overload tripping or short circuit tripping has occurred.

Abstract: A motor protector of the type having a snap acting thermostatic element is shown particularly adapted for use with compressor motors in which a conventional three pin header is mounted on the compressor casing to allow electrical energization of the motor. An improved heat transfer path is formed between the windings of the motor and the thermostatic element of the protector by suspending the protector from one of the motor pins in optimum heat conductive relation therewith and thermally separated from the compressor casing and any component mounted on the other two pins.

Abstract: A surge protector with first and second electrodes, with a heat sensitive member and with a contact member which is electrically connected with the first electrode and which is mounted so as to be brought into contact with the second electrode upon the temperature of the heat sensitive member reaching a predetermined value when receiving heat from the protector. In an embodiment, the heat-sensitive member is composed of a material whose shape is a function of its temperature, such as a shape memory alloy. The heat sensitive member can also serve as the contact member.

Abstract: An electrical lighting fixture adapted for recessed mounting has structure for mounting and energizing a lamp and has an insulation detecting protector device adapted to interrupt operation of the lamp to prevent overheating of the fixture if thermal insulation is disposed around the fixture in such a way as to excessively block heat dissipation from the fixture. The protector device has structure for mounting the device on the fixture to be subject to representative fixture conditions, has a thermally responsive switch which is actuatable in response to heating to a selected temperature for interrupting operation of the lamp, and has an electrical resistance heater which is thermally coupled to the switch for actuating the switch if thermal insulation excessively blocks dissipation of heat from the protector device.

Abstract: The protective circuit against overpoling and overloading of an electronic consumer includes a combination of a zener diode connected parallel to the consumer and a parallel connection of a fuse and a conventional diode connected in series with one power supply terminal. Preferably an additional fuse is connected in series between the power supply and the first-mentioned fuse. In the case of a polarity reversal, a fuse burns out, but after restoring normal operational conditions the protective circuit permits operation of the consumer.

Abstract: An electric motor protection device comprising a body, an electric strip, a plunger, and pressure and temperature sensitive snap discs. The electric strip moves from a current conductive, closed position to a current nonconductive, open position when the current conducted through the strip exceeds a preset level. The plunger engages the electric strip also to move the strip from the closed position to the open position. The pressure and temperature discs move from normal positions to overcenter positions to engage the plunger and move the electric strip from the closed position to the open position, respectively, when the vapor pressure forces on the pressure disc and the temperature of the temperature disc exceed preset values.

Abstract: A protective means for a series capacitor in a high-voltage network comprises a voltage-dependent resistor (varistor) arranged in parallel with the series capacitor, a spark gap arranged in parallel with the varistor for shunting the latter when it becomes overloaded, a current-sensing member, for example a current transformer, for sensing the current through the varistor, an energy absorption detector for sensing the temperature of the varistor, and a pulse transformer electrically or magnetically connected to the current-sensing member, for triggering the spark gap. During normal operation of the network and the series capacitor the current-sensing member is short-circuited by a normally closed switching device.

Abstract: A thermoswitch is physically located on a portion of the current supply connector between the current source and the exciter winding of the starter motor. The portion, constructed as a simple strip with flaps holding the thermostat, influences the temperature-dependent control portion of the thermoswitch according to heating in the armature, field winding, and brushes of the starter motor. The thermoswitch turns OFF the starter system by interrupting current supply to the kick-in starter relay.

Abstract: A recessed lighting unit for supporting an energizing lamp adapted to fit into an electrical socket using a housing. The electrical socket and lamp are mounted in the housing. The housing includes an opening for the passage of light from the lamp to the area to be illuminated. A source of power runs to the socket through a wireway. A heat protection mechanism interrupts the flow of electrical power to the lamp and socket upon the generation of excess heat in the vicinity of the housing. The heat protection mechanism is mounted immediately adjacent the housing in the wireway and forms a structural unit with the housing and a junction box.

Abstract: A circuit interrupter includes a circuit breaker mechanism having a trip coil energized by a current transformer to separate the contacts upon command of a microcomputer-based trip unit during overcurrent conditions. A bimetallic normally-open thermal switch is mounted on the internal conductors of the breaker and is connected in parallel with the trip unit to energize the trip coil when the conductors overheat. The thermal switch is also connected to the interrupt terminal of the microcomputer to cause appropriate display and alarm information upon activation of the thermal switch.

Abstract: A circuit breaker, having a latching mechanism and a solenoid senses current through a circuit. The sensed current is converted to a proportional voltage. A current rating plug and receptacle system, responsive thereto, provides a standardized voltage. The proportional voltage is applied across a resistor in series with parallel connected permanent shunt resistor and replaceable plug resistor. The standardized voltage is obtained across the parallel connection. A peak detector provides an approximate true peak value voltage of the standardized voltage. An instantaneous trip circuit, a ground fault detector, and both short term and long term delay circuits provide trip signals upon certain conditions. Upon the presence of any trip signal, an OR circuit provides a control signal to gate an SCR having a thermal switch coupled across its anode and cathode. A supply voltage is applied across a serial connection of the anode, the cathode, and the solenoid.

Abstract: A combination starter-protector device adapted for removable mounting in electrical contacting engagement onto at least a pair of male terminals of a dielectric plug device secured to an apparatus housing. The combination starter-protector device has a casing, a PTCR disposed therein, and a switch in the casing for association in thermal coupling relation with the PTCR. A spring associated with the casing is adapted for releasable securing engagement with the apparatus housing so as to maintain the combination starter-protector device against displacement from the electrical contacting engagement thereof with the at least male terminal pair of the dielectric plug device when the combination starter-protector device is removably mounted thereto.

Abstract: A metal oxide varistor (MOV) is directly electrically connected between a line conductor and ground to dissipate the energy associated with voltage surges appearing on the line conductor. A thermostatic switch, in the form of a resilient arm held in electrical connection with one of the MOV electrodes by low melting point solder, opens in response to a failing MOV to insert a spark gap electrically in series with the MOV. Overvoltage protection is thus maintained, albeit limited to higher level voltage surges.

Abstract: A protective disconnect to prevent overheating of electrical apparatus is described. The device consists of a cutting member accepting a conductor and capable, upon closure, of severing said conductor. The cutting member is surrounded by a thermoconstrictive material which, upon being subjected to heat at a certain temperature, actuates said member.

Abstract: An electric cigar lighter for automobiles and the like, comprising a holder device presenting an outwardly facing socket, and an ignitor plug receivable in the socket. The plug comprises a manually operable part, and carries a heating element which is electrically connected in circuit with a normally-closed heat-responsive switch that is disposed in the holder device. The socket, in addition to its grounding circuit, has a "hot" contact which is engageable with a cooperable contact on the plug to effect the circuit through the heating element when the manually operable part is depressed. The holder device also carries a bimetallic member which is engageable with one of the parts of the switch. The member normally occupies a closed-circuit position wherein it is separated from the one switch part.

Abstract: A circuit breaker having an electronic fault sensing and trip initiating unit which provides increased versatility and ability to coordinate the circuit breaker with other interrupting and protective devices in a wide variety of electrical distribution systems. Electronic circuits and components are provided to vary the ampere rating of the breaker, to adjust current carrying capacity, to provide a long time delay trip, a short time delay trip and an instantaneous trip depending on the amplitude of high fault currents, to provide a ground fault trip, to shorten or lengthen the trip time for short time delay faults and for ground faults, and to provide shunt trip capability. The tripping mechanism is magnetic and mechanical, and includes a plunger movable between a trip and non-trip position controlled by an electronic switch in the electronic circuitry, and a toggle mechanism which is unlatched by the plunger when it moves to the trip position.

Abstract: An automatic electric cigar lighter, and especially a cigar lighter igniting unit as used for automobiles and the like. The cigar lighter has a holder which presents an outwardly facing socket, and embraces a unique ignitor plug that is received and stored in the socket. At its inner end the plug has a heating element for electrical connection in the circuit of a heat-responsive switch which is also carried by the plug. The latter comprises a manually operable part by which the heat-responsive switch can be closed to complete the heating circuit through the element. A bimetallic member is also carried by the plug, being engageable with one of the switch parts and normally having a circuit-opening position wherein it maintains the one switch part separated from the other. The member is shifted to a closed-circuit position when the plug is actuated. In both positions it receives radiant heat when the heating element is incandescent.