Ground fault circuit interrupter incorporating miswiring prevention circuitry

• US 6,226,161 B1
• Filed: 08/09/1999
• Issued: 05/01/2001
• Est. Priority Date: 07/08/1993
• Status: Expired due to Term

• Current Assignee: Leviton Manufacturing Company Incorporated
• Original Assignee: Leviton Manufacturing Company Incorporated
• Inventors: Gershen, Bernard, Neiger, Benjamin, Rosenbaum, Saul
• Primary Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US09/370,352
• Time in Patent Office: 631 Days
• Field of Search: 361/42-50, 340/635, 340/650, 340/653, 340/654, 340/657
• US Class Current: 361/45
• CPC Class Codes: H02H 3/04 with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18
• CPC Class Codes: H02H 3/338 also responsive to wiring error, e.g. loss of neutral, break

Abstract

A ground fault circuit interrupter (GFCI) with built in intelligence is described that includes circuitry to automatically indicate a device miswiring condition. When a GFCI is wired with its AC and LOAD terminals reversed, downstream devices are still protected in the event of a ground fault but the duplex receptacle on the GFCI itself is not. The invention incorporates miswiring sense circuitry that automatically triggers the generation of visual and audible alarms in the event a miswiring condition is sensed. The invention employs an alarm inhibiting technique that incorporates sense circuitry connected to the AC terminals on one side of the internal GFCI switches or relays and alarm generation circuitry connected to the LOAD terminals on the opposite side.

Claims

1. A ground fault circuit interrupter device electrically connected between a source of electrical power and a load for interrupting a flow of electrical current from said source of electrical power to said load when a ground fault condition is present comprising:

a) a first selectively operable switch in a hot line leading from said power source to said load, said first switch operable in a first condition to permit the flow of current from said power source to said load in said hot line and operable in a second condition to prevent the flow of current in said hot line from said power source to said load;

b) a second selectively operable switch in a neutral line leading form said power source to said load, said second switch operable in a first condition to permit the flow of current from said power source to said load in said neutral line and operable in a second condition to prevent the flow of current in said neutral line from said power source to said load;

c) a ground fault detector coupled between said hot line and said neutral line on a line side of said first and second operable switches to detect ground faults and produce a first output signal indicative of the detection of a ground fault condition;

d) a power supply for producing a power signal;

e) first connecting means interposed between said ground fault detector and said first and second selectively operable switches, wherein an absence of said first output signal from said ground fault detector permits said first and second switches to remain in their first condition and a presence of said first output signal from said ground fault detector causes said first and second selectively operable switches to switch to their second condition to prevent the flow of current between said power source and said load;

f) a sensing device coupled between said hot line and said neutral line, said sensing device providing an inhibit output signal when current is flowing in both said hot line and said neutral line and providing an operating output signal in the event of the interruption of current flow in at least one of said hot and neutral lines;

g) an alarm generator coupled to said sensing means and responsive to said operating output signal and coupled to said power supply and responsive to said power signal to produce an alarm signal when both said operating output signal and said power signal are present and responsive to said inhibit output signal and power signal when both said inhibit output and said power signal are present to prevent the production of said alarm signal; and

h) said power supply is coupled to said hot line before and after said first selectively operable switch and is coupled to said neutral line before and after said second selectively operable switch.

2. A ground fault circuit interrupter device, as defined in claim 1, wherein said first selectively operable switch is a relay switch.

3. A ground fault circuit interrupter device, as defined in claim 1, wherein said second selectively operable switch is a relay switch.

4. A ground fault circuit interrupter device, as defined in claim 2, wherein said second selectively operable switch is a relay switch.

5. A ground fault circuit interrupter device, as defined in claim 1, further comprising:

a) a duplex receptacle coupled between said hot line after said first selectively operable switch, and said neutral line after said second selectively operable switch.