WO2026024331A1 - Afci line side terminal/shunt - Google Patents

Abstract

An arc fault circuit breaker (AFCI) includes a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a shunt portion, the shunt portion including one or more sensing pins; an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault.

Description

PATENT APPLICATION PA02983 (1640-115 PCT) AFCI LINE SIDE TERMINAL/SHUNT CROSS REFERENCE TO RELATED APPLICATIONS [0001] The present application claims the benefit of and priority to U.S. Provisional Patent Application No. 63/675,420, filed on July 25, 2024. The entire disclosure of the foregoing application is hereby incorporated by reference herein. TECHNICAL FIELD [0002] The present disclosure relates to an arc fault circuit interrupter (AFCI). BACKGROUND [0003] Household appliances are typically connected via plugs to electrical receptacles which have at least a hot terminal and neutral terminal. When an appliance operates, current is conveyed to the appliance through the terminals. An electrical arc can occur when electrical current flows outside of the intended conductive paths (e.g., through air) rather than through the intended conductive paths, and such a condition is commonly referred to as an arc fault. Some causes of arc faults can be the result of connections that are not electrically and/or mechanically robust. [0004] Arc faults are potentially dangerous due to the high temperatures of the arcs. Thus, some arcs may have a potential of creating damage. [0005] A protection device that is used to detect arcs and whose output is used to trigger a circuit interrupting mechanism is referred to as an arc fault circuit interrupter (AFCI). [0006] In one example, US Patent 7,003,435 discloses an apparatus and method for a arc fault detector, and is incorporated herein by reference as if fully set forth. PATENT APPLICATION PA02983 (1640-115 PCT) SUMMARY [0007] In an aspect of the present disclosure, an arc fault circuit breaker (AFCI) includes a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a shunt portion, the shunt portion including one or more sensing pins; an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault. [0008] In an aspect of the AFCI, the spacing is set to provide a predetermined resistance. [0009] In an aspect of the AFCI, the line terminal includes a contact, wherein the contact, the shunt portion, and the sensing pins are integrally formed together. [0010] In an aspect of the AFCI, the shunt portion is part of the conductive path. [0011] In an aspect of the AFCI, the load terminal is configured to provide branch circuit current, wherein the branch circuit current flows through the shunt portion. [0012] In an aspect of the AFCI, the contact of the line terminal further includes a plurality of contacts; wherein the shunt portion provides electrical communication between the plurality of contacts; and the plurality of contacts are part of the conductive path. [0013] In an aspect of the AFCI, the contacts, shunt portion and sensing pins are composed of a same material. [0014] In an aspect of the AFCI, the AFCI includes a printed circuit board (PCB), wherein the sensing pins are soldered to the PCB. [0015] In an aspect of the AFCI, the arc fault detection circuit resides on the PCB. PATENT APPLICATION PA02983 (1640-115 PCT) [0016] In an aspect of the AFCI, the arc fault detection circuit measures a voltage across the sensing pins to detect an arc fault. [0017] In an aspect of the AFCI, upon the voltage across the sensing pins being indicative of an arc, the AFCI electronics cause the circuit interrupter to break the electrical contact between the line terminal of the AFCI and the load terminal of the AFCI. [0018] In an aspect of the AFCI, the AFCI includes a sensing core, the sensing core in electrical communication with the arc fault detection circuit, wherein the arc fault detection circuit detects an arc fault based on a signal from the sensing pins, a signal from the sensing core, or both. [0019] In an aspect of the AFCI, the shunt portion is integrally formed with the line terminal. [0020] In an aspect of the AFCI, the shunt portion is integrally formed with the load terminal. [0021] In an aspect of the AFCI, one of the plurality of sensing pins is configured to provide a ground reference voltage to the arc fault detection circuit. [0022] In an aspect of the AFCI, the one or more sensing pins are spaced apart from one another. [0023] In an aspect of the AFCI, the shunt portion includes a plurality of sensing pins and one or more amplifiers in electrical communication with at least two of the plurality of sensing pins. [0024] In an aspect of the present disclosure, an arc fault circuit breaker (AFCI) includes a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a nickel- manganese-copper alloy shunt portion, the shunt portion including one or more sensing pins; PATENT APPLICATION PA02983 (1640-115 PCT) an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault. [0025] In an aspect of the AFCI, the nickel-manganese-copper alloy comprises 84.2% copper, 12.1% manganese, and 3.7% nickel. [0026] In an aspect of the present disclosure, an arc fault circuit breaker (AFCI) includes a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a shunt portion, the shunt portion including a plurality of sensing pins the plurality of sensing pins including a first sensing pin, a second sensing pin, and a third sensing pin; a first amplifier in electrical communication with the first sensing pin and the second sensing pin; a second amplifier in electrical communication with the first sensing pin and the third sensing pin; an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault. [0027] The details of one or more aspects of this disclosure are set forth in the accompanying drawings and the description below. Other aspects, features, and advantages will be apparent from the description, the drawings, and the claims that follow. BRIEF DESCRIPTION OF THE DRAWINGS [0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of this disclosure and, together with a general PATENT APPLICATION PA02983 (1640-115 PCT) description of this disclosure given above, and the detailed description of the embodiment(s) given below, serve to explain the principles of this disclosure, wherein: [0029] FIGS. 1A and 1B are perspective views showing an embodiment of a circuit breaker including an Arc Fault Circuit Interrupter (AFCI), in accordance with the principles of the disclosure; [0030] FIG.2A is a side view of an example line side terminal/shunt of the AFCI shown in FIGS.1A and 1B, in accordance with the principles of the disclosure; [0031] FIG. 2B is a perspective view of the example line side terminal/shunt of the AFCI shown in FIGS.1A and 1B, in accordance with the principles of the disclosure; [0032] FIG.2C is a perspective view of an example shunt of the line side terminal/shunt of the AFCI shown in FIGS.2A and 2B, in accordance with principles of the disclosure; [0033] FIG. 2D is a perspective view of the example line side terminal/shunt of the AFCI shown in FIGS.2A and 2B, in accordance with the principles of the disclosure; [0034] FIG. 3 is a perspective view showing internal components of an example embodiment of the AFCI of FIGS. 1A and 1B, in accordance with the principles of the disclosure; and [0035] FIG.4 is an example schematic diagram showing the operation of the AFCI of FIGS 1A and 1B, in accordance with the principles of the disclosure. [0036] The figures depict embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the present disclosure described herein. PATENT APPLICATION PA02983 (1640-115 PCT) DETAILED DESCRIPTION [0037] The present disclosure relates to circuit interrupting devices for opening and closing electrical communication between line terminals (e.g., input) and load terminals (e.g., output) of a device. Electrical communication between the line and load terminals may be enabled by establishing a conductive path between the line and load terminals. The devices described herein may be of any suitable type such as, without limitation, ground fault circuit interrupters (GFCIs), arc fault circuit interrupters (AFCIs), ground fault protection equipment (GFPE), and suitable combinations thereof (e.g. AFCI/GFCI breakers). Generally, circuit interrupting devices according to the present disclosure include a circuit interrupter (e.g., a solenoid), a user accessible actuator, a fault detection circuit, a test circuit, and other suitable components. Optionally, such a circuit interrupting device may include elements to prevent electrical communication between the line and load terminals unless the circuit interrupter is successfully tested via the test circuit. It is contemplated that the circuit interrupter, reset portion, reset lockout mechanism and trip portion may be combined or otherwise implemented in a variety of ways without departing from the spirit or scope of the present disclosure. In an embodiment, described herein is an AFCI having a shunt configured to detect arc faults. Such a shunt may be used in place of, or in addition to, one or more sensing coils (e.g., a current sensing coil, differential coil, Rogoski coil). [0038] The causes of arcing are numerous, for example: aged or worn insulation and wiring; mechanical and electrical stress caused by overuse, over currents or lightning strikes; loose connections; and, excessive mechanical damage to insulation and wires. Several types of arcing may occur in electrical installations (e.g., buildings), for example: series arcing, parallel arcing, and harmless arcing. Series arcing occurs in series with a load. In this instance the load limits the current flowing in the arc. Parallel arcing occurs between phase and neutral or between phase and ground. In this instance the arc is in parallel with any load present and the PATENT APPLICATION PA02983 (1640-115 PCT) source impedance provides the only limit to the current flowing in the arc. It is important for any arc detection system that both series arcing and parallel arcing be detected and mitigated. On the other hand, harmless arcing (e.g., that due to a fan motor or drill) does not represent a hazard. Such harmless arcs may occur during normal operation of certain common electrical devices may be found in brushed motors (typically with signals in the range of 2-4 MHz), switching power supplies, ballasts, and dimmers. Unwanted arcing (e.g., series and parallel arcing) may typically generate a signal within a 4-10 MHz frequency range, which is typically much higher than signals generated by harmless arcs. [0039] A circuit breaker including arc detection may include a line side phase and neutral terminal as well as load side phase and neutral terminals. The line side phase terminal is capable of transmitting electrical power to the load side phase terminal when the line side phase terminal is in electrical communication with the load side phase terminal. Similarly, the line side neutral terminal is capable of transmitting electrical power to the load side neutral terminal when the line side neutral terminal is in electrical communication with the load side neutral terminal. The line side phase and neutral terminals connect to a power source, and the load side phase and neutral terminals connect to a branch circuit having one or more loads. These terminals may be, for example, any suitable electrical fastening devices, such as, but not limited to binding screws, lugs, binding plates, jaw contacts, pins, prongs, sockets, and/or wire leads, which secure conductive paths to the circuit breaker, and conduct electricity. [0040] The circuit interrupting and reset portions use electromechanical component(s) to break and reestablish the conductive path between line and load phase terminals, and between line and load neutral terminals, respectively. Examples of such electromechanical components include solenoids, bimetallic components, hydraulic components, switches, relays, contactors, or any other suitable components capable of being electromechanically engaged so as to break or reestablish conductive paths between the line and load terminals. In some PATENT APPLICATION PA02983 (1640-115 PCT) embodiments, circuit interrupters are activated in response to specific fault types, such as the presence of an overcurrent, a ground fault, an arc fault, or a combination thereof. Additionally, the same circuit interrupter may be used to protect against overcurrent, ground fault, arc fault conditions, or combinations thereof. Additionally, there may be individual circuit interrupters configured to react, respectively, to overcurrent, ground fault, or arc fault protection. Such, the individual circuit interrupters may be configured to share certain components. [0041] To protect against overcurrent, arc faults, and ground faults, the circuit interrupter breaks the electrical continuity between the line and load phase terminals by opening the circuit when a fault is detected. For example, first electrical contact may be moved away from a second electrical contact to open the conductive paths may be removed. [0042] As mentioned above, an AFCI may include coil components for connecting to a breaker panel. The coil may provide an input to detection electronics for detecting an arc fault. [0043] In accordance with the brief description of the drawings, FIGS.1A and 1B are perspective views showing an embodiment of a circuit breaker including an AFCI (circuit breaker AFCI) 100, in accordance with the principles of the disclosure. As shown in FIGS.1A and 1B, the circuit breaker AFCI 100 includes a housing 101, which contains one or more of the components described above. However, persons of skill in the art will appreciate components of a circuit breaker AFCI 100 may also be included that may not be shown in the Figures. [0044] For example, the circuit breaker AFCI 100 includes a line side phase terminal 110 having a shunt portion (e.g., a shunt 112) disposed within the housing. The line side phase terminal 110 is configured to be connected to the line side connector on a circuit breaker panel (now shown). In this manner, the line side phase terminal 110 is connected to the power source. In other embodiments, a shunt portion may be included in one or more of a line side phase PATENT APPLICATION PA02983 (1640-115 PCT) terminal, a line side neutral terminal, a load side phase terminal, or a load side neutral terminal. In the case of a circuit breaker having a plurality of poles, a shunt portion may be included in one or more of the terminals of the plurality of poles. FIG.2A is a side view of an example line side phase terminal 110 of the circuit breaker AFCI 100 shown in FIGS.1A and 1B, and FIG. 2B is a perspective view of the example line side phase terminal 110 of the AFCI shown in FIGS.1A and 1B, in accordance with the principles of the disclosure. [0045] The line side phase terminal 110 includes a pair of opposing jaws 111 which are adapted to make electrical contact with the line side terminal (e.g., stab) of the breaker panel. A shunt 112 is formed into the line side phase terminal 110 (e.g., the shunt is integral to the line side terminal). The line side terminal also includes a contact portion 113. The shunt 112 includes a plurality of sensing pins 114. As shown in FIGS. 2A and 2B, the shunt 112 is disposed at an end of the line side phase terminal 110. [0046] The contact portion 113 of the line side phase terminal 110 may be electrically connected to the circuitry of the circuit breaker AFCI 100. Accordingly, the contact portion 113 provides, in various embodiments, an electrical connection between the pair of opposing jaws 111 that are connected to the line voltage, and the breaker trip mechanism. [0047] FIG. 2C is a perspective view of the example shunt 112 of the line side terminal/shunt of the AFCI shown in FIGS. 2A and 2B, in accordance with principles of the disclosure. In various embodiments, as shown in FIG.2C, the shunt 112 is triangular in shape and has a first end 121 and a second end 122, where the second end includes the sensing pins 114 extending from the second end 122 of the shunt 112. The sensing pins 114 are generally rectangular in shape, in various embodiments. However, other shapes may be utilized to form the sensing pins 114. [0048] The sensing pins 114 provide an electrical connection to the circuitry of the circuit breaker AFCI 100. More specifically, the sensing pins 114 provide an electrical PATENT APPLICATION PA02983 (1640-115 PCT) connection to the arc fault detection portion of the circuitry (described below). It should be noted that the number of sensing pins 114 may vary depending on a number of conductors to be monitored for an arc fault. [0049] In various embodiments, the shunt 112 may be generally triangular in shape including a first side 118A, a second side 118B and a third side 118C. As shown in FIG. 2C, the sensing pins 114 generally extend from the first side 118A and second side 118B of the shunt 112. The third side 118C is generally integrated with the pair of contacts 111. In various embodiments, the third side 118C is integrated with a common portion of the pair of contacts 111. [0050] FIG. 2D is a perspective view of the example line side terminal/shunt of the AFCI shown in FIGS.2A and 2B, in accordance with the principles of the disclosure. As shown in FIG.2D, an arrow depicts a direction of flow of current I through the line side phase terminal 110. [0051] In various embodiments, the current I flows from the branch circuit through the pair of contacts 111, then shunt 112 and contact portion 113. Accordingly, the sensing pins 114 measure the voltage at various points along the path of current I as it flows through the shunt 112. [0052] FIG. 3 is a perspective view showing internal components of an example embodiment of the circuit breaker AFCI 100 of FIGS. 1A and 1B, in accordance with the principles of the disclosure. As shown in FIG. 3, the line side phase terminal 110, and its associated components, is located at a corner of the circuit breaker AFCI 100. A load terminal 115 is provided in the circuit breaker AFCI 100 that provides an electrical connection to the branch circuit and any connected loads. In various embodiments, the branch circuit may include various electrical devices (e.g., receptacles, motors, appliances, lighting, etc.). PATENT APPLICATION PA02983 (1640-115 PCT) [0053] In various embodiments, the circuit breaker AFCI 100 includes a sensing core 116 and a moveable contact 117. The sensing core 116 includes one or more cores used to supplement AFCI/GFCI detection to provide additional trip capability for the circuit breaker AFCI 100. In various embodiments, the moveable contact 117 is part of the trip mechanism of the circuit breaker AFCI 100 and operates to make or break contact with the line terminal/shunt 110 to make or break an electrical connection between the line terminal/shunt 110 and the and the load terminal 115. Persons of skill in the art will appreciate the operation of the sensing core 116 and the moveable contact 117. [0054] In various embodiments, the circuit breaker AFCI 100 includes detection electronics, such as AFCI detection electronics described in more detail below. The AFCI detection electronics may be situated on a printed circuit board in the circuit breaker AFCI 100 and disposed anywhere within the circuit breaker AFCI 100. [0055] FIG.4 is an example schematic diagram showing the circuit breaker AFCI 100 of FIGS 1A and 1B, in accordance with the principles of the disclosure. As shown in FIG. 4, the terminal shunt 110 is connected to line voltage/current via the pair of opposing jaws 111, AFCI detection electronics (e.g., circuit breaker circuitry) 410 and a breaker trip mechanism (e.g., circuit interrupter) 420. [0056] The pair of opposing jaws 111 is in electrical contact with the contact portion 113, allowing electrical current flow between the line current and the contact portion 113. The contact portion 113 is in electrical communication with the breaker trip mechanism 420, which is in electrical communication with the load terminal 115 via a disconnect mechanism. In various embodiments, the pair of opposing jaws 111, shunt 112 and contact portion 113 are formed into a single part composed of the same material. For example, the pair of opposing jaws 111, shunt 112 and contact portion 113 are formed may be formed out of any suitable metal or combination of metals (e.g., copper, zinc, brass, manganese, nickel). One such PATENT APPLICATION PA02983 (1640-115 PCT) example is a nickel-manganese-copper alloy (84.2% copper, 12.1% manganese, and 3.7% nickel). This alloy, also known as MANGANIN® (a trademark of Isabellenhütte Heusler GmbH & Co. KG), has a precision resistance and is characterized by low temperature coefficient between 20 and 50 °C with a parabolic shape of the R(T) curve, high long-term stability of electrical resistance, extremely low thermal EMF versus copper and good working properties. The current on the branch circuit flows from line to load along a current path. Generally, the current path runs from the pair of opposing jaws 111 through the shunt 112, to the contact portion 113, and then out the load terminal 115. [0057] In various embodiments, the disconnect mechanism of the breaker trip mechanism 420 may include contacts that make (close) and break (open) in order to enable and disable, respectively, the flow of current from the line to the load. For example, in various embodiments, the disconnect mechanism contacts may make contact with one another to allow current to flow during normal operation. In various embodiments, the breaker trip mechanism includes the moveable contact 117. [0058] In various embodiments, upon a condition detected by the breaker trip mechanism 420 necessitating opening of the contacts, the breaker trip mechanism 420 causes the opening of the contacts (e.g., moveable contact 117) to break current flow from the line to the load. For example, in various embodiments, overcurrent protection may be provided by the circuit breaker AFCI 100. Accordingly, if the current between the line and the load exceeds a current threshold, the breaker trip mechanism may cause the contacts to open and cease conducting electricity to the load. [0059] In various embodiments, the sensing pins 114 are in electrical communication with the AFCI detection electronics 410. Accordingly, current on the branch circuit introduces a voltage drop across the sensing pins 114 that is detected by the AFCI detection electronics 410. If an arc fault is detected by the AFCI detection electronics 410, the AFCI detection PATENT APPLICATION PA02983 (1640-115 PCT) electronics 410 controls the breaker trip mechanism 420 to open the contacts and stop the flow of current between the line and the load. [0060] In various embodiments, the sensing pins 114 may be soldered to a printed circuit board (PCB) in the circuit breaker AFCI 100. In various embodiments, the sensing pins 114 of the shunt 112 may be spaced at a calculated distance apart to give a specific resistance. The AFCI detection electronics 410 of the PCB reads the voltage across sets of sensing pins 114 to detect arc faults. For example, since the sensing pins 114 on the shunt 112 are a known resistance, voltage may be measured across the sensing pins 114 which can be used to calculate the current in the circuit by using Ohms Law (e.g., I = V/R where I is the current in amps, V is the voltage in volts, and R is the resistance in ohms). The measured and calculated values mentioned above may be used to detect arc faults. In one embodiment, there may be two sensing pins 114 having a relatively large spacing and known resistance therebetween. The two sensing pins 114 may be connected to an amplifier having a relatively small gain where the first amplifier is configured to sense a series arc. In another embodiment, there may be two sensing pins 114 having a relatively small spacing and known resistance therebetween. The two sensing pins 114 may be connected to an amplifier having a relatively large gain where the amplifier is configured to sense a parallel arc. In still a further embodiment, there may be three sensing pins 114. In this embodiment, the first and second sensing pins 114 have a relatively large spacing and known resistance therebetween. The first and second sensing pins 114 may be connected to a first amplifier having a relatively small gain where the first amplifier is configured to sense a series arc. The first and third sensing pins 114 have a relatively small spacing and known resistance therebetween. The first and third sensing pins 114 may be connected to a second amplifier having a relatively large gain where the second amplifier is configured to sense a parallel arc. In this embodiment, the first sensing pin 114 may also be referred to as a common sensing pin 114. In some embodiments, the common sensing pin 114 PATENT APPLICATION PA02983 (1640-115 PCT) may also be used to provide a reference voltage to the circuit on the PCB. In other embodiments, an additional sensing pin apart from the common sensing pin may be used to provide a reference voltage to the circuit on the PCB. The AFCI detection electronics may detect the presence of an arc based on a variety of factors including the voltage sensed by the sensing pins 114, the voltage between line phase and line neutral (e.g., input voltage waveform), and one or more sensing coils. The AFCI detection may include comparing the waveform sensed by the sensing pins 114 with the input voltage waveform. [0061] In various embodiments, the shunt 112 is a single part utilizing a single material and the sensing pins 114 are directly soldered to the PCB without the use of wires. In various embodiments, the AFCI detection electronics 410 is an example arc fault detector that may include circuitry (e.g., electronics) that is configured to detect an arc fault based on readings across the sensing pins 114. [0062] Persons skilled in the art will understand that the structures and methods specifically described herein and shown in the accompanying figures are non-limiting exemplary embodiments, and that the description, disclosure, and figures should be construed merely as exemplary of particular embodiments. This disclosure is not limited to the precise embodiments described, and that various other changes and modifications may be effected by one skilled in the art without departing from the scope or spirit of the disclosure. Additionally, the elements and features shown or described in connection with certain embodiments may be combined with the elements and features of certain other embodiments without departing from the scope of this disclosure, and that such modifications and variations are also included within the scope of this disclosure. Accordingly, the subject matter of this disclosure is not limited by what has been particularly shown and described. [0063] Particular embodiments of the present disclosure are described above with reference to the accompanying drawings. However, it is to be understood that the disclosed PATENT APPLICATION PA02983 (1640-115 PCT) embodiments are merely exemplary embodiments of the present disclosure and may be embodied in various forms. Well-known functions or constructions are not described in detail so as to avoid obscuring the present disclosure in unnecessary detail. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present disclosure in virtually any appropriately detailed structure. [0064] For the purposes of promoting an understanding of the principles of the present disclosure, reference is be made to particular embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless understood that no limitation of the scope of the present disclosure is thereby intended. Any alterations and further modifications of the inventive features illustrated herein, and any additional applications of the principles of the present disclosure as illustrated herein and above, which would occur to one skilled in the relevant art and having possession of this disclosure, are to be considered within the spirit and scope of the present disclosure.

Claims

PATENT APPLICATION PA02983 (1640-115 PCT) WHAT IS CLAIMED IS: 1. An arc fault circuit breaker (AFCI) comprising: a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a shunt portion, the shunt portion including one or more sensing pins; an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault. 2. The AFCI of claim 1, wherein the spacing is set to provide a predetermined resistance. 3. The AFCI of claim 1, wherein the line terminal includes a contact, wherein the contact, the shunt portion, and the sensing pins are integrally formed together. 4. The AFCI of claim 3 wherein the shunt portion is part of the conductive path. 5. The AFCI of claim 4 wherein the load terminal is configured to provide branch circuit current, wherein the branch circuit current flows through the shunt portion. 6. The AFCI of claim 4 wherein the contact of the line terminal further comprises: PATENT APPLICATION PA02983 (1640-115 PCT) a plurality of contacts; wherein the shunt portion provides electrical communication between the plurality of contacts; and the plurality of contacts are part of the conductive path. 7. The AFCI of claim 3, wherein the contacts, shunt portion and sensing pins are composed of a same material. 8. The AFCI of claim 1, further comprising a printed circuit board (PCB), wherein the sensing pins are soldered to the PCB. 9. The AFCI of claim 8, wherein the arc fault detection circuit resides on the PCB. 10. The AFCI of claim 8, wherein the arc fault detection circuit measures a voltage across the sensing pins to detect an arc fault. 11. The AFCI of claim 10, wherein upon the voltage across the sensing pins being indicative of an arc, the AFCI electronics cause the circuit interrupter to break the electrical contact between the line terminal of the AFCI and the load terminal of the AFCI. 12. The AFCI of claim 1, further comprising a sensing core, the sensing core in electrical communication with the arc fault detection circuit, wherein the arc fault detection circuit detects an arc fault based on a signal from the sensing pins, a signal from the sensing core, or both. PATENT APPLICATION PA02983 (1640-115 PCT) 13. The AFCI of claim 1, wherein the shunt portion is integrally formed with the line terminal. 14. The AFCI of claim 1, wherein the shunt portion is integrally formed with the load terminal. 15. The AFCI of claim 1 wherein one of the plurality of sensing pins is configured to provide a ground reference voltage to the arc fault detection circuit. 16. The AFCI of claim 11, wherein the one or more sensing pins are spaced apart from one another. 17. The AFCI of claim 1, wherein the shunt portion includes a plurality of sensing pins and one or more amplifiers in electrical communication with at least two of the plurality of sensing pins. 18. An arc fault circuit breaker (AFCI) comprising: a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a nickel- manganese-copper alloy shunt portion, the shunt portion including one or more sensing pins; an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and PATENT APPLICATION PA02983 (1640-115 PCT) a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault. 19. The AFCI of claim 18 wherein the nickel-manganese-copper alloy comprises 84.2% copper, 12.1% manganese, and 3.7% nickel. 20. An arc fault circuit breaker (AFCI) comprising: a line terminal; a load terminal, wherein a conductive path is configured to be opened and closed to selectively provide electrical communication between the line terminal and the load terminal; wherein at least one of the line terminal and the load terminal includes a shunt portion, the shunt portion including a plurality of sensing pins the plurality of sensing pins including a first sensing pin, a second sensing pin, and a third sensing pin; a first amplifier in electrical communication with the first sensing pin and the second sensing pin; a second amplifier in electrical communication with the first sensing pin and the third sensing pin; an arc fault detection circuit in electrical communication with the sensing pins of the shunt portion; and a circuit interrupter, in electrical communication with the arc fault detection circuit, the circuit interrupter is configured to open the conductive path when the arc fault detection circuit detects an arc fault.