Electricity: magnetically operated switches – magnets – and electr – Electromagnetically actuated switches – Automatic circuit-interrupting devices
Reexamination Certificate
2002-12-30
2004-05-11
Barrera, Ramon M. (Department: 2836)
Electricity: magnetically operated switches, magnets, and electr
Electromagnetically actuated switches
Automatic circuit-interrupting devices
C361S042000, C200S043020
Reexamination Certificate
active
06734769
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field
The present invention relates generally to resettable circuit interrupting devices and systems and more particularly to a ground fault circuit interrupter (GFCI) device and receptacle having plug blocking means.
2. Description of the Related Art
Many electrical wiring devices have a line side, which is connectable to an electrical power supply, a load side which is connectable to one or more loads and at least one conductive path between the line and load sides. Electrical connections to wires supplying electrical power or wires conducting electricity to one or more loads can be at the line side and load side connections. The electrical wiring device industry has witnessed an increasing call for circuit breaking devices or systems which are designed to interrupt power to various loads, such as household appliances, consumer electrical products and branch circuits. In particular, electrical codes require electrical circuits in home bathrooms and kitchens to be equipped with ground fault circuit interrupters (GFCI). Presently available GFCI devices, such as the device described in commonly owned U.S. Pat. No. 4,595,894 ('894), use an electrically activated trip mechanism to mechanically break an electrical connection between the line side and the load side. Such devices are resettable after they are tripped by, for example, detection of a ground fault. In the device disclosed in the '894 patent, the trip mechanism used to cause the mechanical breaking of the circuit (i.e., the conductive path between the line and load sides) includes a solenoid or trip coil. A test button is used to test the trip mechanism and circuitry is provided to sense faults. A reset button is provided to reset the electrical connection between the line and load sides.
However, instances may arise where an abnormal condition such as a lightning strike may result not only in a surge of electricity at the device which can cause a tripping of the device but can also disable the trip mechanism used to cause the mechanical breaking of the circuit. This can occur without the knowledge of the user. Under such circumstances an unknowing user, faced with a GFCI which has tripped, may press the reset button which, in turn, will cause the device with an inoperative trip mechanism to be reset without the ground fault protection being available.
Further, an open neutral condition, which is defined in Underwriters Laboratories (UL) Standard PAG 943A, may exist with the electrical wires supplying electrical power to such GFCI devices. If an open neutral condition exists with the neutral wire on the line (versus load) side of the GFCI device, an instance may arise where a current path is created from the phase (or hot) wire supplying power to the GFCI device through the load side of the device and a person to ground. In the event that an open neutral condition exists, a GFCI device which has tripped, may be reset even though the open neutral condition may remain.
Commonly owned U.S. Pat. No. 6,040,967, which is incorporated herein in its entirety by reference, describes a family of resettable circuit interrupting devices capable of locking out the reset portion of the device if the circuit interrupting portion is non-operational or if an open neutral condition exists. Circuit interrupting devices normally have a user accessible load side connection such as a GFCI protected receptacle in addition to line and load side connections such as binding screws. The user accessible load side connected receptacle can be used to connect an appliance such as a toaster or the like to electrical power supplied from the line side. The load side connection and the receptacle are typically electrically connected together. As noted, such devices are connected to external wiring so that line wires are connected to the line side connection and load side wires are connected to the load side connection. However, instances may occur where the circuit interrupting device is improperly connected to the external wires so that the load wires are connected to the line side connection and the line wires are connected to the load connection. This is known as reverse wiring. Such wiring is prevalent in new construction, where power is not yet provided to the residence branch circuits and the electrician has difficulty in distinguishing between the line side and load side conductors. In the event the circuit interrupting device is reverse wired, the user accessible load connection may not be protected, even if fault protection to the load side connection remains.
A resettable circuit interrupting device, such as a GFCI device, that includes reverse wiring protection, and optionally an independent trip portion and/or a reset lockout portion is disclosed in U.S. Pat. No. 6,246,558, ('558) assigned to the same assignee as this invention and incorporated herein by reference in its entirety. Patent '558 utilizes bridge contacts located within the GFCI to isolate the conductors to the receptacle contacts from the conductors to the load if the line side wiring to the GFCI is improperly connected to the load side when the GFCI is in a tripped state. The trip portion operates independently of the circuit interrupting portion used to break the electrical continuity in one or more conductive paths in the device. The reset lockout portion prevents reestablishing electrical continuity of an open conductive path if the circuit interrupting portion is not operational or if an open neutral condition exists.
While the breaking of the electrical circuit and the utilization of bridge contacts provides electrical isolation protection between the load conductors and the receptacle contacts when the GFCI is in a tripped or non-conducting state, means which can prevent the prongs of a plug from being inserted into the receptacle of a GFCI when in a non-conducting state, either with or without the bridge contacts is desired to provide added user safety.
SUMMARY OF THE INVENTION
In one embodiment, the circuit interrupting device such as a GFCI includes phase and neutral conductive paths disposed at least partially within a housing between the line and load sides. The phase conductive path terminates at a first connection capable of being electrically connected to a source of electricity, a second connection capable of conducting electricity to at least one load and a third connection capable of conducting electricity to at least one user accessible load through a receptacle. Similarly, the neutral conductive path terminates at a first connection capable of being electrically connected to a source of electricity, a second connection capable of providing a neutral connection to the at least one load and a third connection capable of providing a neutral connection to the at least one user accessible load through the receptacle. The first and second connections can be screw terminals.
The GFCI also includes a circuit interrupting portion disposed within the housing and configured to cause electrical discontinuity in one or both of the phase and neutral conductive paths between the line side and the load side upon the occurrence of a predetermined condition. A reset portion activated by depressing a spring loaded reset button disposed at least partially within the housing is configured to reestablish electrical continuity in the open conductive paths. The reset button assumes a first or a second position which is determined by the conductive state of the GFCI. When the GFCI is in a conducting state, the reset button is substantially fully depressed within the housing of the GFCI, here referred to as a first position. When the GFCI is in a non-conducting state, the reset button projects outward beyond the top surface of the housing of the GFCI, here referred to as the second position.
The GFCI also includes a reset lockout that prevents reestablishing electrical continuity in either the phase or neutral conductive path, or both conductive paths if the circuit interrupting portion is not operating properly. Depression of the res
Germain Frantz
Stewart Stephen
Barrera Ramon M.
Leviton Manufacturing Co. Inc.
Sutton Paul J.
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