Ground fault circuit interrupter (GFCI) with a secondary test switch contact protection

• US 6,697,238 B2
• Filed: 12/31/2001
• Issued: 02/24/2004
• Est. Priority Date: 02/02/2001
• Status: Active Grant

• Current Assignee: Hubbell, Inc.
• Original Assignee: Hubbell, Inc.
• Inventors: Bonilla, Nelson, DeBartolo, Joseph V. Jr.
• Primary Examiner(s): Toatley, Jr., Gregory J.
• Assistant Examiner(s): KITOV, ZEEV V
• Application Number:
  US10/032,064
• Publication Number:
  US 20020145838A1
• Time in Patent Office: 785 Days
• Field of Search: 361/42, 361/45, 361/49, 361/50, 361/104, 361/44, 361/46, 335/18
• US Class Current: 361/42
• CPC Class Codes: H01H 13/64 wherein the switch has more than two electrically distinguishable positions, e.g. multi-position push-button switches
• CPC Class Codes: H01H 83/04 with testing means for indicating the ability of the switch or relay to function properly
• CPC Class Codes: H02H 3/05 with means for increasing reliability, e.g. redundancy arrangements for logic circuits H03K19/003
• CPC Class Codes: H02H 3/331 responsive to earthing of the neutral conductor H02H3/338 takes precedence
• CPC Class Codes: H02H 3/335 the main function being self testing of the device
• CPC Class Codes: H02H 3/338 also responsive to wiring error, e.g. loss of neutral, break

Abstract

A GFCI is provided that has secondary test switch contacts. In case closing of the primary test switch contacts fails to trip the GFCI, subsequent closing of the secondary test switch contacts results in a short circuit between the AC input terminals of the GFCI. The short circuit blows a fuse disposed on the line side of the GFCI. The blowing of the fuse disables the GFCI and/or provides an indication to the user that the GFCI is defective.

Claims

1. A ground fault circuit interrupter (GFCI) for an AC electrical receptacle, comprising:

first and second input terminals for connection to the line and neutral sides, respectively, of an AC source;

first and second output terminals for connection to the line and neutral sides, respectively, of an AC receptacle outlet;

a fuse circuit containing a fuse and coupled to at least one of said first and second input terminals and said first and second output terminals;

first and second conductive paths extending, respectively, between said first input terminal and said first output terminal and between said second input terminal and said second output terminal;

a first set of electrical contacts connected in said first and second conductive paths, respectively, in order to selectively connect said input terminals to said output terminals when said contacts are closed and to selectively disconnect said input terminals from said output terminals when said contacts are open;

a control circuit for causing said contacts to open in response to an imbalance in current flow through said first and second conductive paths that is indicative of a ground fault condition at an AC load connected to said AC receptacle outlet;

a primary test switch for selectively connecting one of said first and second input terminals to one of said second and first output terminals, respectively, in order to create an imbalance in current flow through said first and second conductive paths and thereby cause said control circuit to open said contacts; and

a secondary test switch adapted to be actuated in response to and following actuation of said primary test switch to complete said fuse circuit and thereby blow said fuse, wherein the blown fuse in said fuse circuit changes the operational state of said GFCI.

2. A GFCI as in claim 1, wherein said blown fuse results in said GFCI being disabled.

3. A GFCI as in claim 1, wherein said blown fuse results in said GFCI operating as a receptacle without GFCI protection.

4. A GFCI as in claim 1, wherein a visual indicator is provided to indicate the operational state of said GFCI.

5. A GFCI as in claim 4, wherein said visual indicator is extinguished in the event said fuse is blown.

6. A GFCI as in claim 4, wherein said visual indicator is capable of providing at least two colors to indicate the operational state of said GFCI.

7. A GFCI as in claim 4, wherein said operational state comprises at least one of:

normal operation of said GFCI;

an imbalance of current flow in said GFCI;

receptacle operation of said GFCI without GFCI protection; and

reverse wiring of said GFCI.

8. A GFCI as in claim 1, wherein said blown fuse results in a loss of power to said control circuit.

9. A GFCI as in claim 1, wherein reverse wiring protection is provided for said GFCI.

10. A GFCI as in claim 1, wherein said fuse in said fuse circuit is blown in the event that said GFCI is reverse wired.

11. A method for providing fuse protection for a ground fault circuit interrupter (GFCI) for an AC electrical receptacle having a pair of input terminals, a pair of output terminals, a pair of electrical contacts, a control circuit, and a pair of conductive paths extending between said input terminals and said output terminals, said method comprising:

providing a fuse circuit containing a fuse and coupled to at least one of said input and output terminals;

opening said contacts via said control circuit in response to an imbalance in current flow through said conductive paths that is indicative of a ground fault condition at an AC load connected to said AC receptacle outlet, each of said pair of contacts connected to a respective conductive path in order to selectively connect said input terminals to said output terminals when said contacts are closed and to selectively disconnect said input terminals from said output terminals when said contacts are open;

selectively connecting via actuation of a primary test switch at least one of said input terminals to at least one of said output terminals in order to create an imbalance in current flow through said conductive paths and thereby cause said control circuit to open said contacts;

actuating a secondary test switch in response to and following actuation of said primary test switch to complete said fuse circuit and thereby blow said fuse, wherein the blown fuse in said fuse circuit changes the operational state of said GFCI.

12. The method of claim 11, wherein said blown fuse results in said GFCI being disabled.

13. The method of claim 11, wherein said blown fuse results in said GFCI operating as a receptacle without GFCI protection.

14. The method of claim 11, wherein a visual indicator is provided to indicate the operational state of said GFCI.

15. The method of claim 14, wherein said visual indicator is extinguished in the event said fuse is blown.

16. The method of claim 14, wherein said visual indicator is capable of providing at least two colors to indicate the operational state of said GFCI.

17. The method of claim 14, wherein said operational state comprises at least one of:

normal operation of said GFCI;

an imbalance of current flow of said GFCI;

receptacle operation of said GFCI without GFCI protection; and

reverse wiring of said GFCI.

18. The method of claim 11, wherein said blown fuse results in a loss of power to said control circuit.

19. The method of claim 11, wherein reverse wiring protection is provided for said GFCI.

20. The method of claim 11, wherein said fuse in said fuse circuit is blown in the event that said GFCI is reverse wired.