Patent Publication Number: US-2022216687-A1

Title: Apparatus, systems and methods for performing ground fault self-testing

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 63/032,288, filed on May 29, 2020, which is hereby incorporated by reference herein in its entirety as if set forth fully herein. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure generally relates to apparatuses, systems, and methods for performing ground fault self-testing. 
     BACKGROUND OF THE DISCLOSURE 
     Electronic devices can include or be coupled with ground-fault circuit interrupters (GFCIs) to shut off electric power to a load in the event of a ground fault. For example, a GFCI can compare phase current in a phase conductor with neutral current in a neutral conductor to determine a difference between the phase and neutral currents. If the GFCI detects a difference, the GFCI can shut off electric power to the load. If the GFCI does not detect a difference, then the GFCI can provide electric power to the load. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     Electronic devices configured with a GFCI can turn on or off electric power to a load responsive to detecting a ground fault, such as a difference between an input current and an output current that is greater than a threshold. However, GFCIs may either always stay off after being plugged in to electric power, or turn on automatically after being plugged in to electric power. To maintain a state of the GFCI, portable GFCIs can use electrically held relays, which may include additional hardware to implement self-testing features. However, when electrically held relays are reset, the electrically held relay may enter a default state that may be improper given a state of the circuit of the device. Thus, systems, methods and apparatus of this technical solution can provide a device that implements an electrically held relay that appropriately manages a state of the electrically held relay using ground fault self-testing. This technical solution can include a latching relay designed to maintain an ON or OFF state without using power to maintain the state. 
     At least one aspect of this technical solution is directed to a circuit interrupter device for selectively connecting a source of AC power from a line side to a load side of the circuit interrupter device. The circuit interrupter device can include a controller powered by the source of AC power from the line side. The controller can initialize a self-test. The controller can determine whether the self-test was successful. The controller can output a self-test result signal based on whether the self-test was successful. The circuit interrupter device can include an electrically-held relay having an ON state and an OFF state. The electrically-held relay can be in electrical communication with the controller. The electrically-held relay can remain in the OFF state until the self-test result signal indicates the self-test was successful. The electrically-held relay can transition to the ON state if the self-test result signal indicates the self-test was successful. When the electrically-held relay is in the OFF state, the load side of the circuit interrupter device is not in electrical communication with the source of AC power. When the electrically-held relay is in the ON state, the load side of the circuit interrupter device is in electrical communication with the source of AC power. 
     In some aspects, the circuit interrupter device can include a differential sensor configured to detect a current imbalance. The self-test can be determined to have been successful if a simulated current imbalance is detected by the differential sensor. In some aspects, the circuit interrupter device can include a plurality of electrically conductive paths. The differential sensor can detect the current imbalance between the plurality of electrically conductive paths. The electrical communication between the source of AC power and the load side of the circuit interrupter device can be established by the plurality of electrically conductive paths, wherein the self-test further comprises creating a simulated current imbalance between the plurality of electrically conductive paths. 
     In some aspects, the circuit interrupter device can include two controllers, such as a first controller and a second controller that is in electrical communication with the first controller. The first controller can initialize the self-test and determine whether the self-test was successful. The first controller can output the self-test result signal based on whether the self-test was successful. The second controller can receive the self-test result signal from the first controller. If the self-test was successful, the second controller can cause the electrically-held relay to enter the ON state. In some aspects, the first controller can initialize the self-test responsive to receiving a test initiation signal. In some aspects, the second controller can output a test initiation signal to the first controller upon receiving an input from a user, wherein the test initiation signal causes the first controller to initiate the self-test. 
     In some aspects, the circuit interrupter device can include a user-accessible button operatively coupled to the second controller. An input from a user can be an actuation of the user-accessible button. 
     The circuit interrupter device can include a filter circuit in electrical communication with the first controller and the second controller. The filter circuit can receive the self-test result signal from the first controller. The filter circuit can filter the self-test result signal, and output the filtered self-test result signal to the second controller. 
     The circuit interrupter device can include a housing, and the circuit interrupter device can be at least partially disposed within the housing. The circuit interrupter device can include an electrical plug configured to selectively establish electrical communication between the circuit interrupter device and the source of AC power. 
     The controller can initialize the self-test upon establishment of electrical communication between the line side of the circuit interrupter device and the source of AC power. The controller can initialize the self-test periodically. 
     In some aspects, the circuit interrupter device can include a first switching element and a second switching element electrically coupled in series with the first switching element. The electrically-held relay can be electrically coupled in series with one of the first switching element or the second switching element. The controller can control the electrically-held relay by energizing the first switching element, the second switching element, or both the first and second switching elements. Upon failure of the first switching element, the second switching element, or both the first and second switching elements, the electrically held relay can be maintained in its OFF state. 
     In some aspects, the circuit interrupter is mounted on a panel. The circuit interrupter can include a voltage measurement circuit configured to measure a magnitude of voltage of the AC power. The AC power AC power is removed when the measured magnitude is lower than a lower limit or greater than an upper limit. 
     At least one aspect of this disclosure is directed to an apparatus to perform ground fault self-testing. The apparatus can include a first controller. The first controller can be powered from a source of AC power from a line side. The first controller can receive, from a second controller, a signal to initialize a self-test. The first controller can determine that the self-test was successful. The first controller can output a successful self-test result signal to the second controller responsive to determining that the self-test was successful. The apparatus can include a plurality of switching elements. The apparatus can include an electrically-held relay in electrical communication with the plurality of switching elements. The second controller can be powered from the source of AC power from the line side. The second controller can output, to the first controller responsive to the system for performing ground fault self-testing powering on, the signal to initialize the self-test. The second controller can receive, from the first controller, the successful self-test result signal. The second controller can turn on the electrically-held relay that selectively establishes electrical communication between the source of AC power and a load based on the successful self-test result signal. The electrically-held relay can be powered from the source of AC power from the line side and selectively establish electrical communication between the source of AC power and the load if at least one of the plurality of switching elements is operational. 
     In some aspects, the apparatus can include a differential sensor configured to detect a current imbalance. The self-test is determined to have been successful if a simulated current imbalance is detected by the differential sensor. 
     The apparatus can include a reset-and-test button. The second controller can monitor a state of the reset-and-test button. The output of the successful self-test result signal to the second controller responsive to the determination that the self-test was successful can include outputting the signal to initialize the self-test responsive to a determination that the state of the reset-and-test button is that the reset-and-test button has been depressed. 
     The apparatus can include a first visual indicator that indicates that the self-test was successful. The apparatus can include a second visual indicator that indicates that the self-test was not successful. In some aspects, the first visual indicator can include a green light-emitting diode (LED), and the second visual indicator can include a red LED. 
     The apparatus can include a first switching element and a second switching element both connected in series to the electrically-held relay. The second controller can control the electrically-held relay using the first switching element and the second switching element. 
     At least one aspect of this disclosure is directed to a method for selectively connecting a source of AC power from a line side to a load side of a circuit interrupter device. The method can include one or more controllers of the circuit interrupter device initializing a self-test. The one or more controllers can be powered from the source of AC power from the line side. The method can include the one or more controllers determining whether the self-test was successful. The method can include the one or more controllers outputting a self-test result signal based on whether the self-test was successful. The method can include an electrically-held relay of the circuit interrupter device staying in an OFF state until the self-test result signal indicates the self-test was successful. The electrically-held relay can be in electrical communication with the one or more controllers and be powered from the source of AC power from the line side. When the electrically-held relay is in the OFF state, the load side of the circuit interrupter device is not in electrical communication with the source of AC power, and when the electrically-held relay is in the ON state, the load side of the circuit interrupter device is in electrical communication with the source of AC power. The method can include the electrically-held relay entering an ON state if the self-test result signal indicates the self-test was successful. 
     In some aspects, the one or more controllers can include a first controller and a second controller in electrical communication with the first controller. The method can include the first controller initializing the self-test. The method can include the first controller determining whether the self-test was successful. The method can include the first controller outputting the self-test result signal based on whether the self-test was successful. The method can include the second controller receiving the self-test result signal from the first controller. The method can include the second controller causing, if the self-test was successful, the electrically-held relay to enter the ON state. 
     The method can include the first controller initializing the self-test responsive to receiving a test initiation signal. In some aspects, the method can include providing a housing. The circuit interrupter device can be at least partially disposed within the housing. The method can include providing an electrical plug configured to selectively electrically couple the circuit interrupter device to the source of AC power. In some aspects, the method can include periodically initializing, by the one or more controllers, the self-test. 
     At least one aspect of this disclosure is directed to a circuit interrupter device for selectively connecting a source of AC power from a line side to a load side of the circuit interrupter device. The circuit interrupter device can include a controller, powered by the source of AC power from the line side. The circuit interrupter device can include an electrically-held relay having an ON state and an OFF state. When the electrically-held relay is in the OFF state, the load side of the circuit interrupter device is not in electrical communication with the source of AC power. When the electrically-held relay is in the ON state, the load side of the circuit interrupter device is in electrical communication with the source of AC power. The circuit interrupter device can include a first switching element and a second switching element electrically coupled in series with the first switching element. The electrically-held relay is electrically coupled in series with one of the first switching element or the second switching element. The controller can control the electrically-held relay by energizing the first switching element, the second switching element, or both first and second switching elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, aspects, features, and advantages of the disclosure will become more apparent and better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: 
         FIGS. 1A-1B  illustrate event and state flows for automatic and manual-reset electrically-held relay devices, in accordance with aspects described herein. 
         FIG. 2  is a block diagram showing a system for performing ground fault self-testing, in accordance with aspects described herein. 
         FIG. 3  is a block diagram for a relay of a system for ground fault self-testing, in accordance with aspects described herein. 
         FIG. 4  is a block diagram for a system having separate reset and test buttons and that implements a system for ground fault self-testing, in accordance with aspects described herein. 
         FIG. 5 a    is a block diagram for a device that implements a system for ground fault self-testing. 
         FIG. 5 b    is a block diagram for a device that implements a system for ground fault self-testing, in accordance with aspects described herein. 
         FIG. 6 a    is a depiction of a comparative example of a device that implements a system for ground fault self-testing. 
         FIG. 6 b    is a depiction of an example device that implements a system for ground fault self-testing, in accordance with aspects described herein. 
         FIG. 7  depicts a method for ground fault self-testing, in accordance with aspects described herein. 
         FIG. 8  is a schematic diagram for a circuitry for ground fault self-testing, in accordance with aspects described herein. 
     
    
    
     DETAILED DESCRIPTION 
     This disclosure provides systems, methods, and apparatus for performing ground fault self-testing (which may be referred to herein simply as a “self-test”) for a device that implements electrically held relays. This disclosure can also apply to other types of circuit interrupters such as but not limited to arc fault circuit interrupters (AFCI&#39;s), appliance leakage circuit interrupters (ALCI&#39;s), equipment leakage circuit interrupters (ELCI&#39;s), ground fault protection of equipment (GFPE&#39;s), dual function or combination arc fault and ground fault circuit interrupters, or any suitable combination thereof. 
     Electronic devices configured with a GFCI can turn on or off electric power to a load responsive to detecting a ground fault. A ground fault refers to a leakage of current to ground which can potentially represent an electrical shock hazard. Typically, ground faults are detected by measuring a current differential between phase and neutral conductors that is greater than a threshold. Different types of electronic devices can be configured with different types of GFCIs. For example, an electronic device can use a portable GFCI that can provide a self-test capability. A GFCI with a self-test function can periodically and automatically test the ability of the GFCI circuitry to respond to a ground fault. When the self-test function detects a problem with the ability of the GFCI circuitry to respond to a ground fault, the GFCI can turn off (or deny) power to the load without generating an output signal, or provide a visual or audible indication of the detected problem. It is noted that the self-test or manual test capability is possible on a line power device but not on a load powered device. That means turning on a relay on the load powered device can be done by mechanical means and thus, testing on turning on in the load powered device is not possible. 
     A GFCI can use a latching relay to maintain a state of the GFCI when the electronic device is unplugged from electric power, and then plugged back in to electric power. Portable GFCIs, which may be used in construction or outdoor settings, are typically either manual reset or automatically reset. A manual reset portable GFCI will remain off after being plugged in to electric power until a user manually actuates the portable GFCI to provide power to the load. An automatic reset portable GFCI will turn on automatically after being plugged in to electric power without user intervention (assuming proper operation). To maintain a state of the GFCI, portable GFCIs can use electrically held relays, which may include additional hardware to implement self-testing features. However, GFCIs that shut off electric power to a load in the event of a ground fault may not perform as desired electrically held relays are used. 
     For example, electrically held relays can use power to maintain an ON state. If the power used to maintain the ON state is interrupted, the electrically held relays will change to or remain in the OFF state. Alternatively, the electrically held relay will change to or remain in the OFF state if the electrically held relay is an “always off” relay. A portable device that enters an incorrect or erroneous state may hold the relay ON when there is a problem (e.g., a ground fault or other fault), or hold the relay OFF when there is no problem with the circuit of the device. Therefore, electrically held relays may enter a default state that is improper, incorrect, or erroneous given a state of the circuit of the device. 
     Thus, systems, methods and apparatus of the present technical solution can provide a device that appropriately manage a state of the electrically held relay using self-testing. Other technical solutions can alternatively include a latching relay designed to maintain an ON or OFF state without using power to maintain the state. 
     The system of this technical solution can include a first controller and a second controller. The first controller can be a chip to perform self-test (alternatively, the first controller can be connected to, or coupled with a chip to perform self-test). The first controller may otherwise be designed, configured and operational to use a latching relay. However, in electrical communication with suitable circuitry, the first controller can be adapted for use with an electrically held relay. The first controller can process signals from a phase (e.g., hot or ungrounded) and neutral (e.g., grounded) conductor of a circuit. The first controller can determine the difference between these signals to determine, detect or otherwise identify a ground fault (“GF”) or ground neutral (“GN”) condition, and generate an output pulse signal. The first controller can periodically initialize a self-test using a self-test circuitry to inject a simulated ground fault. If the first controller does not detect the simulated ground fault, then the first controller can provide an indication or alert, such as via a blinking light emitting diode (“LED”), that provides a warning that the self-test was a failure. If, after a predetermined number of repeated attempts to simulate a ground fault (“GF”), the first controller still does not detect the simulated ground fault, the first controller can generate and output a pulse or other signal to deny power to a load. Thus, the first controller can deny power responsive to determining the self-test was a failure. After the denial of power, a user can attempt to reset the device by initiating a manual test via a button or other input operationally coupled to the first controller. It should be noted that such a manual test can also be initiated by a user at any time independently of the self-test. 
     To operate an electrically held relay to maintain an appropriate state of the GFCI, the first controller can interface with (e.g., interact with, communicate with, connect with, or otherwise utilize) a second controller. The second controller can monitor an output from the first controller that indicates the result of the self-test. In some cases, the second controller can receive the output of the self-test via a filtering circuit. The second controller can operate a relay through one or more transistors, in electrical communication with a solenoid which, in turn, is in electrical communication with the relay. The relay maintains the appropriate state of the GFCI. For example, a plurality of transistors can be connected in series so that the relay is kept on if both transistors are operating correctly. If one of the transistors fails in an open state, then the relay remains off independent of the signal from the second controller. If one of the transistors were to fail in a closed state (e.g., a short), then the device can operate correctly using another transistor in series with the failed transistor. 
     The second controller can monitor (i.e., check or otherwise identify) the position of a user operated manual button coupled to, connected to otherwise interfacing with the second controller (e.g., an input of the controller being in electrical communication with a set of contacts that are in turn mechanically engaged by a button). The second controller can be operatively coupled to a single manual button that is configured to initiate both a reset and test operation, or the second controller can be operatively coupled to two separate buttons, one of which is a reset button and the other of which is a test button. 
     When the one or more buttons are activated, the second controller can transmit (i.e., send, provide, or otherwise communicate) a signal to the first controller to initiate a manual test. The first controller can conduct the test to determine if the first controller detects a simulated fault signal from the self-test circuitry. Upon determining the test was successful (e.g., the simulated fault is detected), the first controller can generate an output signal or pulse that indicates the test was successful. The first controller can output the signal via a pin of the first controller, such as a silicon controller rectifier (“SCR”) pin. 
     The second controller can detect the pulse, which is output by the first controller responsive to the first controller detecting the test was successful. When the second controller detects this pulse, the second controller can control the relay through the one or more transistors connected to the second controller. If the relay was in the on state, then the second controller can turn off the relay. If the relay was in the off state, then the second controller can turn the relay on. Thus, the relay can be turned on only if both the first controller and the second controller are functioning correctly. If the first controller was unable to or did not detect a fault via the self-test, then the second controller can turn off the relay or keep the relay in the off state, thereby denying power to the load as the device may be malfunctioning . 
     A power supply circuit can provide power to both the first controller and the second controller. In the event the power supply circuit is malfunctioning, then at least one of the first controller and the second controller may not receive proper power, which can cause the relay to be turned off automatically. Thus, the device can be turned on only after successful self-test by the first controller and proper operation of the power supply circuit (e.g., providing a reset lockout function). A reset lockout function can be referred to as a denial of power to the electronic device in case of circuitry malfunctioning. 
     In some cases, the device can be configured with an automatic reset device. The automatic reset device refers to a device that automatically turns on the relay after the device is connected to power. The device can reset after a successful self-test by the first controller. 
     After the device is connected to power, the device can automatically initiate a self-test . For example, the second controller can provide signal to the first controller to cause the first controller to initiate the self-test. The second controller can provide the signal responsive to receiving a signal indicative of self-test initiation. The first controller can perform the self-test. If the self-test performed by the first controller was successful, the first controller can generate and output a signal or pulse. The second controller can receive the signal indicating a successful test, and turn on the relay accordingly. If the first controller does not generate and provide the pulse within a predefined time window, then the second controller can keep the relay off. Thus, the second controller can prevent usage of a device that is malfunctioning. 
     Referring now to  FIGS. 1A-B , example event and state flows for automatic and manual-reset circuit interrupter devices are shown. In brief overview,  FIG. 1A  illustrates a flow diagram for automatic-reset circuit interrupter device  102 .  FIG. 1B  illustrates a flow diagram for a manual-reset circuit interrupter device  114 . The flow charts can include multiple events and relay states corresponding to each event. The devices  102  and  114  can perform the events for self-testing ground fault. The devices  102  and  114  can include one or more component of apparatus  200  depicted in  FIG. 2 . The devices  102  and  114  can turn on the relay or keep the relay off in response to the self-test result. Relay on can refer to a state of the relaying being on, which can result in power being delivered to a load. The relay may be referred to as a latching relay. 
     Referring to  FIG. 1A , and in further detail, the automatic-reset circuit interrupter device  102  can perform events  104 ,  106 ,  108 ,  110 , and  112 . The events can optionally be performed sequentially and consecutively. At event  104 , power is initially applied to the circuit interrupter device  102 . For example, the circuit interrupter device  102  can be plugged into a power outlet or power source. When power is initially applied to the circuit interrupter device  102 , the state of the relay is OFF. When the relay is in the OFF state, the circuit interrupter device  102  denies power to a load connected to the circuit interrupter device  102 . At event  106 , the circuit interrupter device  102  automatically initiates a self-test. The circuit interrupter device  102  automatically initiates a self-test responsive to power being applied to the circuit interrupter device  102 . The state of the circuit interrupter device  102  remains OFF when the circuit interrupter device  102  automatically initiates the self-test. At event  108 , the circuit interrupter device  102  performs ground fault self-testing in response to the automatic initiation of the self-test at event  106 . The state of the circuit interrupter device  102  remains OFF while the circuit interrupter device  102  is performing the self-test. 
     At decision block  110 , the circuit interrupter device  102  determines whether the result of the self-test is a success or failure. If the self-test result is a failure, the state of the circuit interrupter device  102  remains OFF. Thus, the state of the circuit interrupter device  102  remains off from event  104  when power is initially applied to circuit interrupter device  102 , and through the detection of a failed self-test at  110 . After detecting the self-test failure, the circuit interrupter device  102  can automatically attempt to perform another self-test (or continuously perform self-tests for a duration of time), or determine to end the self-test and remain in the OFF state. 
     If the circuit interrupter device  102  determines, at decision block  110 , that the self-test is a success, then the circuit interrupter device  102  turns on the relay at event  112  and provides power to the load. The circuit interrupter device  102  can change the state of the relay from OFF to ON upon detecting a successful self-test. The circuit interrupter device  102  remains in an OFF state from the initial power on, through an automatic self-test, and until the detection of a successful self-test at event  112 , at which point the state of the relay changes to ON. 
     Referring to  FIG. 1B , power is initially applied to a manual-reset circuit interrupter device  114  at event  116 . The manual-reset circuit interrupter device  114  does not automatically begin a self-test at event  118  upon power being applied. Instead, the manual-reset circuit interrupter device  114  stays in an OFF state and waits until a user initiates a manual test. At event  118 , manual-reset circuit interrupter device  114  can detect that the user has initiated a manual test (e.g., a user pressing a button on the manual-reset circuit interrupter device  114 ). At event  120 , the manual-reset circuit interrupter device  114  performs a self-test. 
     At decision block  122 , the manual-reset circuit interrupter device  114  determines whether the result of the self-test is a success or failure. If the self-test result is a failure, the state of the manual-reset circuit interrupter device  114  remains OFF. Thus, the state of the manual-reset circuit interrupter device  114  remains off from event  116  when power is initially applied to manual-reset circuit interrupter device  114 , and through the detection of a failed self-test at  122 . After detecting the self-test failure, the manual-reset circuit interrupter device  114  ends the self-test and remains in the OFF state. 
     If the manual-reset circuit interrupter device  114  determines, at decision block  122 , that the self-test is a success, then the manual-reset circuit interrupter device  114  turns on the relay at event  124  and provides power to the load. The manual-reset circuit interrupter device  114  can change the state of the relay from OFF to ON upon detecting a successful self-test. The manual-reset circuit interrupter device  114  remains in an OFF state from the initial power on, through a user-initiated self-test, and until the detection of a successful self-test at event  124 , at which point the state of the relay changes to ON. 
     Referring now to  FIG. 2 , a block diagram of an apparatus  200  that includes ground fault and/or self-testing in accordance with an aspect is shown. The apparatus  200  may be any electrical system (e.g., a wiring or lighting, system). The apparatus  200  may be required (e.g., by regulation or for compliance with a technical standard) to implement automatic (e.g., periodic) self-testing for ground faults without human intervention, and may be required (e.g., by regulation or for compliance with a technical standard) to interrupt power to a load of the apparatus  200  (or connected to the apparatus  200 ) upon a failure of such a test. In brief overview, the apparatus  200  can include a first controller  202  and a second controller  206 . The first controller  202  can include one or more pins  202   a,    202   b,    202   c,    202   d,  and  202   e  that can receive input signals or provide output signals. The apparatus  200  can include a visual indicator  210  in electrical communication with the first controller  202  via pin  202   e.  The apparatus  200  can include a second controller  206  that includes one or more pins  206   a,    206   b,    206   c,  and  206   d  that can receive input signals or provide output signals. The first controller  202  and the second controller  206  are in electrical communication with each other. The apparatus  200  can include a power supply  212  that provides power to the first controller  202  and the second controller  206 . The power supply  211  can receive power from the power source  216 . The apparatus  200  can include a relay  208 , such as an electrically-held relay. The second controller  206  can provide a signal to the relay  208 . The apparatus  200  can be in electrical communication with a power source  216  that provides power to the relay  208 , and the relay  208  can provide power to a load  218 . For example, the apparatus  200  can be plugged into an electrical receptacle, the electrical receptance being connected, in turn, to a power source  216 . The apparatus  200  can include fault simulation circuitry  214  connected to the first controller  202 . The apparatus  200  can include a button  220  that can cause a signal to be sent to the second controller  206 . The apparatus  200  can include a filtering circuit  204  that transmits a signal between the first controller  202  and the second controller  206  via pins  202   d  and  206   b.  The apparatus  200  can be configured to perform a ground fault self-test, and to manage a state of the relay  208  in an improved manner following a reset of the apparatus  200  (e.g., following an interruption of power supplied by a power source  216 ). 
     Still referring to  FIG. 2 , and in further detail, the first controller  202  can be designed, constructed and operational to initialize a self-test and output a self-test result signal based on whether the self-test was successful. The first controller  202  can include one or more processing chips configured to perform a ground fault self-test on the fault simulation circuitry  214 . The first controller  202  can interface with to one or more components or circuit elements of apparatus  200 , including, for example, the second controller  206 , filtering circuit  204 , visual indicator  210 , fault simulation circuitry  214 , or the power supply  212 . The first controller  202  can include one or more pins for electrical connection with other components of the apparatus  200 . As used herein, the term “pin”, although singular, can refer to an individual pin or a plurality of pins. The first controller  202  can be a controller that would otherwise be configured to control a latching relay. The apparatus  200  can use the first controller  202  in conjunction with the second controller  206  to control an electrically-held relay such as the relay  208 . 
     The first controller  202  can receive a signal via the pin  202   a  to initiate a self-test. The pin  202   a  can be configured to receive such a signal either periodically (e.g., from a component or circuit that periodically outputs a signal to implement the self-test), receive such a signal responsive to a manually input command to implement a self-test, or receive such a signal upon powering on of the apparatus  200 . For example, the first controller  202  may receive the signal to implement the self-test from the second controller  206  (e.g., an output signal from the pin  206   a  of the second controller  206 ). The signal may include a high value, low value, series of values, pattern, or other type of command, instruction, or indication to initiate a self-test. In some aspects, the pin  202   a  can be a push-to-test (“PTT”) pin. In some cases, the first controller  202  can automatically determine to initialize the self-test responsive to the first controller  202  powering on or receiving power from the power supply  212 . In some cases, the first controller  202  can initialize the self-test responsive to receiving a manual test signal via the PTT pin. 
     The pin  202   b  can output one or more signals to implement a self-test. The pin  202   b  can output the signal to fault simulation circuitry  214 . The first controller  202  can use the pin  202   b  to output the signal to implement a self-test responsive to receiving, via the pin  202   a,  a signal to implement a self-test. The pin  202   b  can output a signal that simulates a ground fault in the fault simulation circuitry  214 . The pin  202   b  can be a ground fault test (“GFT”) pin that is in electrical communication with the fault simulation circuitry  214 . Thus, the first controller can initialize a self-test of the system. 
     The first controller  202  can initialize the self-test of the system based on a time interval, responsive to a signal or command from the second controller  206 , or responsive to a manual indication to initiate a self-test. For example, the first controller  202  can include a counter or timer configured for a time interval or time period. The counter can include a countdown timer or other type of timer. The first controller  202 , responsive to the countdown timer expiring, can generate the signal to initiate the self-test and output the signal to the self-test circuitry. 
     The fault simulation circuitry  214  can be designed, constructed, and configured to simulate a ground-fault. The fault simulation circuitry  214  can include any circuitry elements, components, digital or analog components, or modules configured to simulate a ground-fault signal or facilitate a ground-fault test. The fault simulation circuitry  214  can communicate with the first controller  202 . The fault simulation circuitry  214  can include any circuitry of the apparatus  200 . The fault simulation circuitry  214  can include circuitry (e.g., differential and/or ground-neutral (“GN”) cores for ground fault GF and GN condition detection) for simulating a ground fault. The fault simulation circuitry  214  may be required (e.g., by regulation or for compliance with a technical standard) to perform automatic (e.g., periodic) self-testing for ground faults without human intervention. The fault simulation circuitry  214  can include one or more diodes, resistors, or transistors that are connected to create a circuit configured to simulate a ground fault. The fault simulation circuitry  214  can provide a signal indicative of the simulated ground fault with the first controller  202  via the pin  202   c.    
     For example, the fault simulation circuitry  214  can receive a signal or a command from the first controller  202  via the pin  202   b  to conduct a ground fault self-test. In response to receiving the signal from the first controller  202  to conduct the ground fault self-test, the fault simulation circuitry  214  can simulate a ground fault and provide a signal indicative of the simulated ground fault as input to the first controller  202  via the pin  202   c.  The fault simulation circuitry  214  can simulate a ground fault by generating and outputting a signal having a characteristic of electricity that represents a ground fault. The fault simulation circuitry  214  can simulate a ground fault by generating and outputting a signal with a current that is greater than zero or greater than a threshold that indicates a ground fault. The fault simulation circuitry  214  can generate and output a signal for providing an indication of the simulated ground fault to the first controller  202  that is greater than the threshold. The threshold can be any amount of current, including, for example, 3 milliamps, 4 milliamps, 5 milliamps, 6 milliamps, 7 milliamps, 8 milliamps, or more. For example, the fault simulation circuitry  214  can generate and output a signal that is greater than 4 milliamps. 
     The first controller  202  can include, or be coupled with, a differential sensor that receives this signal from the fault simulation circuitry  214  via the pin  202   c  and detects a simulated ground fault. The pin  202   c  can be connected to the fault simulation circuitry  214 . The pin  202   c  can receive one or more signals from the fault simulation circuitry  214 . The signals may constitute at least part of a result of the self-test. The signals may include signals from a differential core for ground fault (GF) condition detection. 
     The first controller  202  can receive or detect the simulated ground fault signal (e.g., an output signal greater than  4  milliamps) from the fault simulation circuitry  214  or differential transformer thereof. The first controller  202  can utilize one or more circuitry elements or differential sensors to analyze, process or otherwise compare the signal with a threshold to detect a ground fault. The first controller  202  can include comparator circuitry, a processor or other digital logic to detect a ground fault. 
     The first controller  202  can detect the simulated ground fault within a time interval of initiating the self-test. The first controller  202  can initiate the self-test via a signal output from the pin  202   b  at a first time. The first controller  202  can then receive the simulated ground-fault signal via the pin  202   c  at a second timestamp. The first controller  202  can detect the ground fault at a third timestamp responsive to receiving the simulated ground-fault signal. The first controller  202  can determine whether the self-test was successful or unsuccessful (e.g., a failure) based on whether the first controller  202  detects the ground fault based on the simulated ground fault signal. In an aspect, the first controller  202  can determine whether the self-test was successful or unsuccessful based on whether the first controller  202  detected the ground fault within a predetermined time interval. The predetermined time interval can be 2 seconds, 1 second, 0.5 second, 0.4 second, 0.3 second or other amount of time. The first controller  202  can determine that the time difference between the first timestamp (e.g., corresponding to when the first controller  202  initiated the self-test) and the third stamp (e.g., corresponding to when the first controller  202  detected the ground fault) is less than the predetermined time interval. If the time difference is less than the predetermined time interval, the first controller  202  can determine the self-test was successful, and output a signal via pin  202   d  that indicates a successful self-test. If, however, the first controller  202  does not detect a ground fault within the predetermined time interval, the first controller  202  does not generate and output any signal via the pin  202   d  during the predetermined time. 
     The first controller  202  can determine to repeat the self-test a predetermined number of times or run the self-test for a predetermined duration. For example, the first controller  202  can repeat the self-test 2 times, 3 times, 4 times, 5 times, 10 times, 20 times, 30 times, 40 times, 50 times, or other number of times before determining that the self-test was a failure. The first controller  202  can run the self-test for a certain duration of time (e.g., 1 second, 2 seconds, 3 seconds, 5 seconds, 10 seconds, 15 seconds, 20 seconds, or another duration), and if the apparatus  200  does not detect a successful self-test during the duration, the apparatus  200  can determine that the self-test was a failure. Thus, the first controller  202  can initiate or execute the self-test multiple times during for a duration of time, and determine whether the self-test was successful based on whether the first controller  202  detects a ground-fault condition within a predetermined time interval. 
     The first controller  202  can provide a signal indicative of the result of the self-test to an indicator. The first controller  202  can provide an indication via the visual indicator  210  or an audio indicator via the pin  202   e  of the apparatus  200 . The visual indicator  210  can include a light emitting diode (LED). The visual indicator  210  can include, for example, a green LED or a red LED. The visual indicator  210  can indicate a result of a self-test, or indicate whether power to the load  218  is on or off. The second controller can provide audio or visual indications, communicate failure over a power line, or communicate failure wirelessly, such as over radio frequency (“RF”) using various protocols such as WiFi, Bluetooth Low Energy, a proprietary RF protocol. 
     The first controller  202  can use the pin  202   e  to output the signal to cause the visual indicator  210  to indicate a result of the self-test. The first controller  202  can generate the signal to cause the visual indicator  210  to provide a visual indication with certain characteristics, such as a color (e.g., red, green, white, blue, etc.), a flashing pattern, or an intensity of the light output. 
     The first controller  202  can output a signal that indicates the result of the self-test to the second controller  206  via the pin  202   d.  In some cases, the pin  202   d  can output the signal to the second controller  206  via a filtering circuit  204 . The signal can be a demand for denial of power to the load  218 . The pin  202   d  can be a silicon controller rectifier (“SCR”) pin. 
     The filtering circuit  204  can be designed, constructed, and configured to filter a signal. The filtering circuitry  204  can include any circuitry, components, elements, digital or analog components, or modules to filter a signal. For example, the filtering circuitry  204  can include one or more resistors and capacitors configured and connected to provide a low pass filter, high pass filter, or bandpass filter. The filtering circuit  204  can include one or more diodes. The filtering circuit  204  can be configured to modify the signal output via the pin  202   d  to the second controller  206  such that the signal is readily handled by the second controller  206 . This can be useful, for example, when implementing the first controller  202  otherwise configured to control a latching relay, such that the first controller  202  need not be updated or modified to provide a signal appropriate for the second controller  206 . 
     The second controller  206  can be designed, constructed, and operational to control the relay  208  that selectively establishes electrical communication between the load  218  and the power supply  216 . The second controller  206  can include circuitry, digital or analog components, elements, or modules. The second controller  206  can interface with one or more component or circuit element of apparatus  200 , including, for example, the first controller  202 , filtering circuit  204 , relay  208 , power supply  212 , or button  220 . The second controller  206  can use one or more pins to control the first controller  202  to perform a ground fault self-test using the fault simulation circuitry  214 . The second controller  206  can use one or more pins to control the relay  208 . 
     The second controller  206  can generate and output a signal to implement (i.e., initiate, initialize, or otherwise cause) a ground-fault self-test to be performed by the first controller  202 . The second controller  206  can output the signal via the pin  206   a  of the second controller  206 . The second controller  206  can provide the signal to the pin  202   a  of the first controller  202 . The second controller  206  can be configured to generate a signal that is compatible with the first controller  202  and input via the pin  202   a.    
     The second controller  206  can determine a ground-fault based on one or more conditions, events, triggers, time intervals, or commands. For example, the second controller  206  can receive a manual indication (e.g., via button  220 ) to implement the ground-fault self-test. The second controller  206  can determine a ground-fault responsive to detecting a power-on condition. The second controller  206  can determine a ground-fault based on a time interval (e.g., every minute, 2 minutes, 5 minutes, 10 minutes, 30 minutes, hourly, 2 hours, 6 hours, 12 hours, 24 hours, 48 hours, weekly, or other time interval). The second controller  206  can determine a ground-fault responsive to detecting an event, such as a power being supplied to the load  218 , or disconnection and re-connection of power to the load  218 , powering on of the apparatus  200  or any component thereof, change in temperature, humidity, contact with water, motion sensor information, proximity detection, or other event or condition. 
     For example, the second controller  206  can output the signal to implement a self-test responsive to power being supplied by the power supply  212  (e.g., following an interruption of the power from the power source  216 , such as following a power reset). For example, the second controller  206  can power-on responsive to the apparatus  200  being plugged into the power source  216  (which, in turn, energizes the power supply  212 ). As part of a power-on or boot-up procedure or process, the second controller  206  can determine to initiate a ground-fault self-test. The second controller  206 , responsive to the determination to initiate the ground-fault self-test, can generate a signal. The signal can include an initialization signal, command, instruction, or other indication that causes the first controller  202  to initiate, execute, perform. or otherwise implement the ground-fault self-test. For example, the second controller  206  can generate a signal with an instruction to initiate a ground-fault self-test and output the signal to the first controller  202 . The first controller  202 , upon receiving the signal output from the second controller  206 , can determine to initiate the ground-fault self-test and generate another signal for transmission to the fault simulation circuitry  214  to cause the fault simulation circuitry  214  to simulate a ground-fault. 
     The second controller  206  can output the signal to implement a self-test responsive to receiving a signal from the button  220  via the pin  206   d.  For example, a user can manually implement the self-test by pushing (i.e., actuating, switching, or otherwise interacting with) the button  220 . The pin  206   d  can receive a signal from the button  220  (e.g., via electrical contacts engaged thereby) after the apparatus  200  powers on. The second controller  206  can monitor a state of the button  220  (e.g., may determine when the button  220  is depressed). Responsive to receiving a signal from the button  220  (e.g., a user pushing the button when the apparatus  200  powers on), the second controller  206  can output the signal to initiate a self-test to the first controller  202 . The button can engage electrical contacts which are, in turn, connected to the power supply  212 . Actuating the button  220  can cause a signal to be input to the pin  206   d  of the second controller  206 . The signal can have a voltage that is based on electricity provided by the power supply  212  to the electrical contacts engaged by the button  220 . For example, actuating the button  220  can cause the electrical contacts to close a circuit between the power supply  212  and the pin  206   d , which can provide a current or signal to the second controller  206  via the pin  206   d.  The second controller  206  can receive this signal, and interpret this signal as an instruction to implement a ground fault self-test. 
     In some cases, the button  220  can be included/incorporated in the power supply  212 . In some cases, the button  220  can be a single reset-and-test button. In some cases, the apparatus  200  can include multiple buttons  220 , such as a separate reset button and a separate test button to provide test and reset functionality. For example, in the case in which the button  220  is a single reset-and-test button, pressing the button  220  when the apparatus  200  is in a tripped state (e.g., the relay  208  is in an OFF state and no power is being delivered to the load  218 ) causes the apparatus  200  to start a self-test. If the self-test was successful, the second controller  206  closes the relay  208  contact, resetting the apparatus  200  and delivering power to the load  218 . When the apparatus  200  is in a reset state, pressing the single reset-and-test button  220  again initiates a self-test. If this self-test is successful, the second controller  206  opens relay  208 , switching the apparatus  200  into a tripped state. If the self-test is unsuccessful, the second controller forces the relay  208  open and outputs an indication that the apparatus  200  is malfunctioning. The apparatus  200  can be later reset when the self-test is successful. 
     The pin  206   b  can receive a signal from the first controller  202  (e.g., via the pin  202   d,  or via the filtering circuit  204 ). The signal from the first controller  202  can be a signal indicating a result of the self-test. The signal from the first controller  202  can be a signal demanding a denial of power to the load  218 . The signal from the first controller  202  can indicate whether the self-test was successful or unsuccessful. The second controller  206  can receive a signal and determine or identify whether the self-test was successful or unsuccessful. The result of the self-test is indicated by outputting a pulse, or by the absence of any such output pulse. For example, an output signal or pulse can indicate a successful self-test, whereas the absence of such an output signal or pulse indicates an unsuccessful self-test. The signal can include a constant signal, or pulse train signal. For example, if the signal has a constant high voltage value, then the second controller  206  can determine that the self-test was a success. If the signal has a constant low voltage value, then the second controller  206  can determine that the self-test was a failure. A high voltage can refer to a voltage above a threshold, such as a 5 volt signal, 10 volt signal, 12 volt signal, or other voltage level the power supply  212  is configured to provide. A low voltage signal can refer to a voltage below a threshold, such as 0 volts, 1 volt, or other 2 volts, for example. The signal can include binary values, a pattern. 
     The second controller  206  can determine how to control the relay  208  based on the signal received at the pin  206   b  indicating the result of the self-test. The second controller  206  can determine the result of the self-test based on the signal. The second controller  206  can use one or more logic devices, circuitry, rules, or programs to determine how to control the relay  208 . The second controller  206  can control (i.e., adjust, modify, maintain, or otherwise manage) the relay  208  responsive to the result of the self-test. The second controller  206  can output a signal to the relay  208  (e.g., to one or more transistors in electrical communication with the relay  208 ) via the pin  206   c.  The second controller  206  can output the signal to the relay  208  responsive to receiving the signal from the first controller  202 , which indicates a result of the self-test, or a demand to deny power to the load  218 . 
     If the second controller  206  determines that the self-test was a success, then the second controller  206  can turn on the relay  208 . Turning on the relay  208  can refer to causing the relay  208  to enter an ON state in which power from the power source  216  is provided to the load  218 . If the second controller  206  determines that the self-test was a failure, then the second controller  206  can turn off the relay  208 . Turning off the relay  208  can refer to causing the relay  208  to enter an OFF state in which power from the power source  216  is denied or otherwise prevented from reaching the load  218 . 
     The second controller  206  can monitor an output from the first controller  202  that indicates the result of the self-test. The second controller  206  can operate a solenoid in electrical communication with the relay  208  through one or more transistors to maintain the appropriate state of the GFCI. For example, the transistors that control the relay  208  can be connected in series so that the relay  208  is kept on if both transistors are operating correctly. If one of the transistors is broken, then the relay  208  remains off independent of controls from the second controller  206 . If one of the transistors were to short, then the device can operate correctly using another transistor. 
     The second controller  206  can detect the pulse, which was output by the first controller  202  responsive to the first controller  202  detecting the test was successful. When the second controller  202  detects this pulse, the second controller  206  can control the relay  208  through the one or more transistors connected to the second controller  206 . If the relay  208  was in the on state, then the second controller  206  can turn off the relay  208 . If the relay  208  was in the off state, then the second controller  206  can turn the relay  208  on. Thus, the relay  208  can be turned on only if both the first controller  202  and the second controller  206  are functioning correctly. If the first controller  202  was unable to or did not detect a fault via the self-test, then the second controller  206  can turn off the relay  208  or keep the relay  208  in the off state, thereby denying power to the load  218  as the apparatus  200  may be malfunctioning or not properly functioning. If the self-test by the first controller  202  was a success, then the second controller  206  can turn on the relay  208  or keep the relay  208  in the on state. 
     In aspects, in a manual reset GFCI system, the second controller  206  can receive a signal from the first controller  202  indicating that the self-test was successful. The second controller  206  can control the relay  208  to enter an on state to provide power to the load  218 . After restoration of power following an apparatus  200  power interruption to the apparatus  200 , the manual reset GFCI system may automatically default the relay  208  to an off state. Accordingly, after a system reset, the second controller  206 , upon powering on, can implement a self-test but will only do so in response to manual intervention by a user. The implementation of the self-test can cause the first controller  202  to conduct a self-test and provide the result to the second controller  206 . If the self-test was successful, the second controller  206  can switch the relay  208  from the off state to the on state. 
     In aspects, in an automatic reset GFCI system, the second controller  206  can receive a signal from the first controller  202  indicating that the self-test was unsuccessful. The second controller  206  can control the relay  208  to enter an off state to deny power to the load  218 . After apparatus  200  restoration of power following a power interruption, the automatic reset GFCI system may automatically conduct a self-test and, if successful, transition the relay  208  to an on state. If the self-test was a failure, the second controller  206  can cause the relay  208  to remain in the off state. The relay  208  can be controlled by one or more transistors which are, in turn, controlled by the second controller  206  (e.g., via the pin  206   c ). 
     The second controller  206  can automatically turn the relay  208  on after a power reset or powering on. The second controller  206  can automatically turn the relay  208  off after a power reset, or keep the relay  208  off until there has been a successful self-test of the GFCI. Thus, the electrically-held relay can be configured to be off when the apparatus  200  powers on, and the second controller  206  can turn on the relay  208  responsive to, and in accordance with, the self-test result signal from the first controller  202  indicating that the self-test signal was successful. 
     The apparatus  200  can include a power supply  212 . The power supply  212  can supply power that is appropriate or configured for the first controller  202  and the second controller  206 , and any components used by the controllers  202  and  206 , to function. The power supply  216  can supply power to the load  218 . For example, the power supply  212  can include one or more components or circuitry that provide power to the first controller  202  and the second controller  206  with characteristics of electricity (e.g., voltage, current, frequency, direct current, alternating current, etc.) that are compatible with the first controller  202  and the second controller  206 . 
     The power supply  212  provides power to one or more components of the apparatus  200 . The power supply  212  can supply power to the first controller  202  or the second controller  206 . The second controller  206  can use the pin  206   a  to output a signal to the first controller  202  to implement a self-test when power from the power supply  212  is provided (e.g., when the power source  216  is turned on, or following a reset of the apparatus  200 ). 
     The load  218  can refer to any type of an electronic device, system or component that can use electricity to perform a task or function. The load  218  can include, for example, a lighting device, appliance, power tool, charger, computing device, electric motor, etc. 
       FIG. 3  is a block diagram showing the second controller  206  and the relay  208  of the apparatus  200  for ground fault self-testing, in accordance with aspects described herein. The relay  208  can be connected to the power source  216 . The relay  208  can deliver power to the load  218 . The relay  208  can be in electrical communication with one or more transistors. The one or more transistors can include a first transistor  302  and a second transistor  304 . The first transistor  302  can be connected to the second transistor  304  in series. The one or more transistors can turn the relay  208  on or off in order to deliver or block delivery of power to the load  218 . 
     The relay  208  can be connected to the second controller  206  via the pin  206   c.  The pin  206   c  can include a first pin  306  and a second pin  308 . The first pin  306  can connect to the first transistor  302 , and the second pin  308  can connect to the second transistor  304 . Thus, the second controller  206  can individually control the state of the first transistor  302  and the second transistor  304  using via the pins  306  and  308 . In some cases, one of the transistors  302  and  304  can function as a backup transistor. For example, the second transistor  304  can be referred to as a backup transistor, while the first transistor  302  can be the active transistor. The second controller  206  can control the state of the relay  208  by changing only the state of the active transistor (e.g., the first transistor  302 ), provided that the first transistor  302  is functioning properly. The second controller  206  can control the state of the relay  208  while the backup transistor (e.g., the second transistor  304 ) remained powered on. However, if the first transistor  302  breaks (e.g., it is shorted to be always on), the second controller  206  can still control the state of the relay  208  by controlling the state of the second transistor  304  via the pin  308 . 
       FIG. 4  is a block diagram showing a system  400  for ground fault self-testing, which has separate reset and test buttons in accordance with aspects described herein. The system  400  can include one or more components, devices, elements, circuits, or modules of the apparatus  200  of  FIG. 2 . For example, the system  400  can include the second controller  206  with the pins  206   a ,  206   b,    206   c  and  206   d.  The second controller  206  can receive power from the power supply  212 . The power supply  212  can include a test button  402  and a reset button  404 . The buttons  402  and  404  can include one or more component or functionality of the button  220  depicted in  FIG. 2 . 
     The test button  402  can, responsive to actuation or interaction, provide an indication to the second controller  206  to implement a ground fault test. The test button  402  can be connected to the pin  206   d  of the second controller  206 . Actuation of the test button  402  can provide a signal to the second controller  206 . The second controller  206  can receive the signal via pin the  206   d . Responsive to the signal (e.g., a pulse), the second controller  206  can test a ground fault by sending a signal or pulse to the first controller  202 . 
       FIG. 5 a    is a block diagram of a device  502   a  for ground fault self-testing, in accordance with aspects described herein. The device  502   a  can include one or more component, circuitry or functionality depicted in  FIGS. 2-4 , including, for example, the apparatus  200 , the system  400 , the first controller  202 , the second controller  206 , or the relay  208 . The device  502   a  can refer to a GFCI device. The device  502   a  can include a test button  502 , a reset button  504 , and a visual indicator  506 . The visual indicator  506  can include one or more component or functionality of the visual indicator  210  depicted in  FIG. 2 . The device  502   a  can conduct a ground fault test responsive to actuation of test button  502  or reset button  504 , or both. The device  502   a  can provide an indication, warning, alert, or other status information via the visual indicator  506 . For example, the device  502   a  can display a green light to indicate that the self-test was successful or that the relay  208  is in an on state and delivering power to a load. The device  502   a  can display a red light to indicate that the self-test was unsuccessful. The device  502   a  can display a flashing or blinking light (e.g., red LED) if the first controller  202  does not detect a simulated ground fault during the self-test. 
       FIG. 5 b    is a block diagram showing a device  502   b  for ground fault self-testing, in accordance with aspects described herein. The device  502   b  can include one or more component, circuitry or functionality depicted in  FIGS. 2-4 , including, for example, the apparatus  200 , the system  400 , the first controller  202 , the second controller  206 , or the relay  208 . The device  502   b  can refer to a GFCI device. The device  502   b  can include a button  520 , a first visual indicator  510 , and a second visual indicator  512 . The first and second visual indicators  510  and  512  can include one or more component or functionality of the visual indicator  210  depicted in  FIG. 2 . The device  502   b  can conduct a ground fault test responsive to actuation of the button  520 , which can be a single reset-and-test button that can provide the functionality of both the test button  402  and the reset button  404  depicted in  FIG. 4 . The device  502   b  can provide an indication, warning, alert, or other status information via the visual indicators  510  and  512 . For example, the device  502   b  can display a green light via the visual indicator  510  to indicate that the self-test was successful or that the relay  208  is in an on state and delivering power to a load. The device  502   b  can display a red light via the second visual indicator  512  to indicate that the self-test was unsuccessful. The device  502   b  can display a flashing or blinking light (e.g., red LED) via the first visual indicator  510  or the second visual indicator  512  if the first controller  202  does not detect a simulated ground fault during the self-test. 
     In some cases, the first visual indicator  510  can display the result of the ground fault test, and the second visual indicator  512  can display the status of the device  502   b  itself, such as a status of the relay  208 , the first controller  202  or the second controller  206 . 
       FIG. 6 a    is a device  600  for ground fault self-testing, in accordance with aspects described herein. The device  600  can include one or more component, circuitry or functionality depicted in  FIGS. 2-4 and 5   a , including, for example, the apparatus  200 , the system  400 , the first controller  202 , the second controller  206 , or the relay  208 . The device  600  can include a reset button  604  such as the reset button  404  of  FIG. 4 , a separate test button  602  such as the test button  404  of  FIG. 4 , and a visual indicator  610  such as the visual indicator  210  of  FIG. 3 . The device  600  can include an enclosure  602 , such as a housing or a case, that encloses the circuitry and other components of the apparatus  200  or system  400 . The enclosure  602  can be formed of any material. The enclosure  602  can be formed of a non-conductive material, such as plastic, rubber, or a combination thereof. The enclosure  602  can include an opening  604  through which a power cable or wire can extend externally from the enclosure  602  and connect to a power source  216 . 
       FIG. 6 b    is a device  601  for ground fault self-testing, in accordance with aspects described herein. The device  601  can include one or more component, circuitry or functionality depicted in  FIGS. 2-4 and 5   b , including, for example, the apparatus  200 , the system  400 , the first controller  202 , the second controller  206 , or the relay  208 . The device  601  can include a reset and test button  620  such as the reset and test button  220  of  FIG. 2 , a first visual indicator  610  such as the first visual indicator  510  of  FIG. 5 b   , and a second visual indicator  612  such as the second visual indicator  512  of  FIG. 5 b   . The first visual indicator  610  can be a green LED, and the second visual indicator  612  can be a red LED. The  601  can turn on one of the green LED or the red LED based on the status of the system, or result of the ground fault self-test. The device  601  can include an enclosure  602 , such as a housing or a case, that encloses the circuitry and other components of the apparatus  200  or system  400 . The enclosure  602  can be formed of any material. The enclosure  602  can be formed of a non-conductive material, such as plastic, rubber, or a combination thereof. The enclosure  602  can include an opening  604  through which a power cable or wire can extend externally from the enclosure  602  and connect to a power source  216 . 
       FIG. 7  depicts a method for ground fault self-testing, in accordance with aspects described herein. The method  700  can be performed by one or more system, circuitry, component, or device depicted in  FIGS. 2-6   b,  including, for example, the apparatus  200 , the system  400 , the first controller  202 , the second controller  206 , the self-test circuit  214 , or the relay  208 . In brief overview, a first controller can initialize a self-test at step  702 . At step  704 , the first controller can determine whether the self-test was successful. At step  706 , the first controller can output, to a second controller, a self-test result signal based on whether the self-test was successful. At step  708 , the second controller can receive the self-test result signal from the first controller. At step  710 , the second controller can control a relay (e.g., an electrically-held relay that establishes electrical communication between a power source and a load based on the self-test result signal. 
     Still referring to  FIG. 7 , at step  702 , the first controller can initialize the self-test responsive to an instruction, indication or command to initialize the self-test. The first controller can initialize the self-test based on a condition, event, trigger, or time interval. For example, the first controller can be configured to periodically initiate a self-test. The first controller can receive a signal from the second controller that request or instructs the first controller to initiate the self-test. The first controller can determine to initiate the self-test responsive to a condition, such as a reset signal or a test signal. The first controller can determine to initiate the self-test responsive to an event, such as powering on of the first controller or the second controller, or upon user intervention. 
     The first controller can initialize the self-test by generating a signal and outputting the signal to a self-test circuit. The first controller can generate a signal that instructs or causes the self-test circuit to simulate a ground fault. The first controller can cause the simulation of a ground fault. The self-test circuit can simulate the ground fault. Detection circuitry (e.g., a differential transformer) can provide a signal to the first controller indicative of the simulated fault. 
     At step  704 , the first controller can determine whether the self-test was successful. The first controller can receive the signal indicative of simulated ground fault (e.g., simulated ground fault signal). The first controller can process the ground fault test. The first controller can compare the simulated ground fault signal from the self-test circuitry with a threshold signal or threshold value to determine whether there is a ground fault. If the first controller determines the simulated ground fault signal is greater than a threshold (e.g., 6 milliamps), then the first controller can detect a ground fault. 
     In some cases, the first controller can repeatedly instruct the self-test circuit to simulate a ground fault, for example until a predetermined duration expires or predetermined number of times. If the first controller does not detect the simulated ground fault, or does not detect the simulated ground fault within the predetermined duration, then the first controller can determine that the result ground fault self-test was unsuccessful or a failure. 
     At step  706 , the first controller can output, to a second controller, a self-test result signal based on whether the self-test was successful. The first controller can output a signal via a pin of the first controller that indicates that the test was successful. 
     At step  708 , the second controller can receive the self-test result signal from the first controller. The second controller can determine whether the result was a success or a failure. The second controller can receive the signal via a filter circuit that filters the signal such that the signal is compatible with the second controller. 
     At step  710 , the second controller can control a relay that selectively establishes electrical communication between a power source and a load based on the self-test result signal. If the result was successful, the second controller can turn on the relay (or allow the relay to continue to be turned on) in order to deliver power from a power source to a load. If the result of the self-test was a failure, then the second controller can turn off the relay or keep the relay off to prevent or deny power from being delivered from the power source to the load. 
     In some cases, the relay can be turned off by default. The initial state of the relay can be off. The second controller can turn on the relay responsive to receiving an indication of a successful self-test. For example, when the system powers on, the relay can be kept off until the second controller receives an indication of a successful self-test. 
       FIG. 8  depicts a schematic diagram of circuitry  800  for ground fault self-testing, in accordance with an aspect. The circuitry  800  can form or be included in the apparatus  200  or the device  600  or  601 , and include components with one or more functions similar to components in at least  FIGS. 2-6 , for example. The circuitry  800  can include a load  804 , a bridge rectifier  808 , a solenoid  812 , a power supply  816 , a microcontroller  820 , a manual test and reset button  824 , a ground-fault circuit interrupter (GFCI) power supply  828 , a GFCI circuit  832 , an LED fault indicator  836 , and a self-test circuit  840 . The circuitry  800  can include an inductor, a resistor, an amplifier, a transistor, or any other electrical components. The electrical components can be in electrical communication with each other via one or more conductive traces on a printed circuit board (PCB), for example. In some implementations, the electrical components can intercommunicate with each other using wireless signal, such as via radio wave or Bluetooth. 
     The load  804  can include one or more devices connected or coupled to the circuitry  800 . The load  804  can be reside in the same housing or reside in a different housing than the circuitry  800 . The load  804  and circuitry  800  can be in electrical communication with each other via a hardwired cable (e.g., a wiring harness) or via an electrical plug and connector. The load  804  may be a resistive load, an inductive load, or a capacitive load. The load  804  can connect to one or more components of the circuitry  800 . For example, the load  804  can include a circuitry independent from the circuitry  800 . The circuitry  800  can include at least one switch, connected to at least one other component in the circuitry  800 , configured to open or close to disconnect or connect to a power source. The switch of the load  804  can be configured by manual operation (e.g., operator manually turning the switch on and off) or automatic operation (e.g., responsive to a signal, periodic, threshold, or other conditions). In aspects, the load  804  can correspond to, or perform one or more similar functions similar to, the load  218  of  FIG. 2 . 
     The bridge rectifier  808  can electrically communicate with other components in the circuitry  800 . For example, the rectifier  808  can connect to the solenoid  812 , a neutral line, one or more transistors, a microcontroller  820 , the power supply  816 , and the GFCI power supply  828 . The rectifier  808  may be a diode bridge rectifier, a full-wave rectifier, or other types of rectifier for AC power conversion. The rectifier  808  can include multiple diodes for configuring the polarity of an AC signal. In some implementations, the rectifier  808  can convert an AC input with both positive and negative polarities to output only positive polarity (e.g., a direct current (DC) output). In aspects, the rectifier  808  can convert the AC input with both polarities to output only negative polarity. The rectifier  808  can transmit signal in a single polarity to the solenoid  812 , the power supply  816 , and the GFCI power supply  828 , for example. 
     In aspects, the rectified voltage can be measured by a voltage measurement circuit (not shown), which can be mounted on a panel version of the circuitry  800 . The voltage measurement circuit can detect a magnitude of the rectified voltage. When the magnitude is less than or equal to a lower limit (e.g., about 65 V) or greater than or equal to an upper limit (e.g., 170 V), the power is removed from the circuitry  800 , thereby preventing load damage during neutral loss at power source. The microcontroller  820  can control one or more light emitting diodes (LEDs) to indicate the power removal. 
     The solenoid  812  can connect to the rectifier  808 , one or more transistors, the power supply  816 , and the GFCI power supply  828 . The solenoid  812  can be in electrical communication with the relay, as described in at least  FIGS. 1-2 . The relay can correspond to, or perform one or more functions similar to, the relay  208 . The solenoid  812  can be operated by the microcontroller  820 . The solenoid  812  may be connected in series with the one or more transistors to maintain appropriate state of the apparatus. For example, the one or more transistors that control the relay can be connected in series to determine the condition of at least one transistor. If all the transistors are operable, electrical signal will flow through the solenoid  812  and the transistors, keeping the relay powered on. However, if at least one of the transistors malfunction or is inoperable, the series connection from the solenoid  812  through the transistors will be open. As the connection is opened, electrical power may not flow through, powering off the relay in electrical communication with the solenoid  812 . In aspects, the solenoid  812  can correspond to, or perform one or more functions similar to, the solenoid as described in at least  FIG. 2 . 
     The power supply  816  may perform similar functionalities as the GFCI power supply  828 . The power supply  816  can be in electrical communication with the microcontroller  820 . The power supply  816  can generate electrical power for operating the microcontroller  820 . The power supply  816  can provide electrical power to the relay, thus establishing electrical communication between the power source and the load  804 . In some cases, the power supply  828  may provide electrical power to the GFCI circuit  832 , in addition to the microcontroller  820 . In some implementations the power supply  816  can correspond to, or perform one or more similar functionalities to, the power source  216 . 
     The microcontroller  820  can be in electrical communication with one or more transistors, the power supply  816 , the manual test and reset button  824  (via respective electrical contacts engaged thereby), and the GFCI circuit  832 . The transistors can be in series with the solenoid  812 . The microcontroller  820  can connect to the GFCI circuit  832  via a silicon controller rectifier (“SCR”) pin and a manual test pin (e.g., push-to-test (“PTT”) pin). In some implementations, the SCR pin and the PTT pin can correspond to, or include similar features as, the pin  202   d  and the pin  202   a  of the first controller  202 , respectively. The microcontroller  820  can send, via manual test pin, at least one signal to the GFCI circuit  832  to initiate a self-test. The microcontroller  820  can monitor an output from the GFCI circuit  832  via the SCR pin, which indicates a result of the self-test. The microcontroller  820  can operate the solenoid  812  by providing electrical signal to the transistors. In some implementations, the microcontroller  820  can correspond to, or perform one or more similar functionalities to, the second controller  206 . 
     The manual test and reset button  824  can be in electrical communication (via electrical contacts engaged thereby) with the microcontroller  820  and the power supply  816 . The button  824  can be manually triggered. For example, an operator can manually push the button  824 . In a further example, the electrical state of the electrical contacts engaged by the button  824  may be changed in response to a timer or a countdown. The electrical contacts engaged by the button  824  can send electrical signal to initiate both test and reset operation of the microcontroller  820 . In some cases, the button  824  can be a first button for initiating the test operation, and a second button for initiating the reset operation. In aspects, the button  824  can correspond to, or perform one or more similar functionalities to, the button  220 . 
     The GFCI power supply  828  can be in electrical communication with the GFCI circuit  832 . The GFCI power supply  828  can provide electrical power for operating the GFCI circuit  832 . In some cases, the GFCI power supply  828  can provide electrical power to the microcontroller  820 , in addition to the GFCI circuit  832 . In aspects, the GFCI power supply  828  can correspond to, or perform one or more similar functionalities to, the power supply  212 . 
     The GFCI circuit  832  can be in electrical communication with at least the self-test circuit  840 , the GFCI power supply  828 , the microcontroller  820 , and the LED fault indicator  836 . The GFCI circuit  832  can receive electrical power from the GFCI power supply  828 . The GFCI circuit  832  can allow electrical communication to be established between a power source and the load  804  in response to detecting a ground fault. The GFCI circuit  832  can receive, from the microcontroller  820 , a signal to initiate self-test via the self-test circuit  840 . The initiation of the self-test tests the ability of the GFCI circuitry to respond to a ground fault. Subsequent to self-testing the circuit, the GFCI circuit  832  can transmit the result of the self-test to the microcontroller  820 . In aspects, the GFCI circuit  832  can correspond to, or perform one or more similar functionalities to, the first controller  202 . 
     The LED fault indicator  836  (e.g., indicator  836 ) can be in electrical communication with the GFCI circuit  832 . The indicator  836  can emit light with varying colors to indicate detection of a simulated ground fault during the self-test. The indicator  836  can be configured to blink, flash, emit light continuously, or initiate other effects. Depending on whether the GFCI circuit  832  detects the ground fault during the self-test, the indicator  836  can be configured to emit different light color or effect. For example, if the GFCI circuit  832  detects simulated ground fault during the self-test, the GFCI circuit  832  can transmit an electrical signal to the indicator  836  to emit green light for visual indication. However, and in further example, if the GFCI circuit  832  does not detect the simulated ground fault during the self-test, the indicator  836  can emit blinking red light, instead of non-blinking green light. In some implementations, the indicator  836  can correspond to, or perform one or more functions similar to, the first visual indicator  510  or the second visual indicator  512 . 
     The self-test circuit  840  can include a test resistor  842 , a ground-neutral (“GN”) core  844 , a differential core  848 . The test resistor  842  creates a predetermined magnitude of current imbalance between phase and neutral conductors. The self-test circuit  840  can include any electrical components or circuitry elements, such as a resistor, a transistor, and one or more diodes. The self-test circuit  840  can be configured to simulate a ground fault. The self-test circuit  840  can be in electrical communication with the GFCI circuit  832 . The self-test circuit  840  can receive an electrical signal from the GFCI circuit  832  to initiate self-testing in response to the GFCI circuit  832  receiving the signal to initiate a self-test. For example, the button  824  may be triggered, sending an electrical signal to the microcontroller  820  to initiate a self-test. Subsequently, the microcontroller  820  can transmit an electrical signal to the GFCI circuit  832  to initiate the self-test operation. Responsive to receiving the electrical signal, the GFCI circuit  832  can send an electrical signal to the self-test circuit  840  to initiate the self-test operation. In aspects, the self-test circuit  840  can correspond to, or perform one or more functions similar to, the fault simulation circuitry  214 . 
     The GN core  844  can be used in connection with the differential core  848  for ground neutral condition detection. A ground neutral condition occurs when neutral and ground conductors are connected both on the line side and the load side of the differential core  848  and the GN core  844 . This results in a conductive loop which then magnetically couples the differential core  848  and GN core  844  together. When this happens, the differential core  848  and GN core  844  create positive feedback which causes an amplifier coupled to the GFCI circuit  832  to oscillate. When the amplifier oscillates, the GFCI circuit  832  interprets this as a ground fault and the electrical communication between the power source and the load is removed. The differential core  848  can be used for ground fault condition detection. 
     While various aspects of the methods and systems have been described, these aspects are exemplary and in no way limit the scope of the described methods or systems. Those having skill in the relevant art can effect changes to form and details of the described methods and systems without departing from the broadest scope of the described methods and systems. Thus, the scope of the methods and systems described herein should not be limited by any of the exemplary aspects and should be defined in accordance with the accompanying claims and their equivalents. 
     References to “or” may be construed as inclusive so that any terms described using “or” may indicate any of a single, more than one, and all of the described terms. References to at least one of a conjunctive list of terms may be construed as an inclusive OR to indicate any of a single, more than one, and all of the described terms. For example, a reference to “at least one of ‘A’ and ‘B’” can include only ‘A’, only ‘B’, as well as both ‘A’ and ‘B’. Such references used in conjunction with “comprising” or other open terminology can include additional items. 
     Reference to “can” may be construed as capability or ability of the subject, which is directly related to “can,” for performing a task and further as one or more alternative aspects of the subject directly related to “can”. 
     Any implementation disclosed herein may be combined with any other implementation or aspect, and references to “an implementation,” “some implementations,” “one implementation” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described in connection with the implementation may be included in at least one implementation or aspect. Such terms as used herein are not necessarily all referring to the same implementation. Any implementation may be combined with any other implementation, inclusively or exclusively, in any manner consistent with the aspects and implementations disclosed herein. 
     Any references to implementations or elements or acts of the systems and methods herein referred to in the singular may also embrace implementations including a plurality of these elements, and any references in plural to any implementation or element or act herein may also embrace implementations including only a single element. References in the singular or plural form are not intended to limit the presently disclosed systems or methods, their components, acts, or elements to single or plural configurations. References to any act or element being based on any information, act or element may include implementations where the act or element is based at least in part on any information, act, or element. 
     The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing,” “involving,” “characterized by,” “characterized in that,” and variations thereof herein, is meant to encompass the items listed thereafter, equivalents thereof, and additional items, as well as alternate implementations consisting of the items listed thereafter exclusively. In one implementation, the systems and methods described herein consist of one, each combination of more than one, or all of the described elements, acts, or components.