Reverse wiring indicator for GFCI receptacles

• US 5,541,800 A
• Filed: 03/22/1995
• Issued: 07/30/1996
• Est. Priority Date: 03/22/1995
• Status: Expired due to Term

• Current Assignee: Hubbell, Inc.
• Original Assignee: Hubbell, Inc.
• Inventors: Misencik, John
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US08/408,397
• Time in Patent Office: 496 Days
• Field of Search: 361/45, 361/49, 361/46, 361/50, 361/42, 361/44, 361/47, 361/48, 340/652, 335/18, 29/593
• US Class Current: 361/45
• CPC Class Codes: H01H 27/04 Insulating plug or plate inserted between normally closed contacts
• CPC Class Codes: H01H 73/14 Indicating lamp structurally associated with the switch
• CPC Class Codes: H01H 83/04 with testing means for indicating the ability of the switch or relay to function properly
• CPC Class Codes: H01R 13/648 Protective earth or shield arrangements on coupling devices , e.g. anti-static shielding coaxially arranged shields H01R24/38
• CPC Class Codes: H01R 13/7135 with ground fault protector H01R13/7132 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 reverse wiring indicator for a GFCI receptacle alerts the installer in the event that the AC source has been improperly wired to the load or feedthrough terminals of the receptacle rather than to the source or input terminals. The reverse wiring indicator operates by open-circuiting one of the load or feedthrough terminals of the receptacle, and may take the form of a removable barrier which inhibits conduction through one of the power contact sets of the GFCI circuit breaker until the receptacle has been installed and successfully tested. The contact set through which conduction is inhibited is the one other than that to which the TEST switch is connected, and the other contact set is allowed to conduct in the normal manner. The removable barrier prevents a current path from being established through the load or feedthrough terminals of the receptacle in the event that the receptacle has been miswired, thereby preventing the TEST switch from falsely tripping the circuit breaker in that situation, but does not prevent the TEST switch from operating normally to trip the circuit breaker if the receptacle has been properly wired. The removable barrier may be provided in the form of a thin strip of electrically insulating material (such as Mylar tape) which is held between one set of closed power contacts and protrudes through the front of the receptacle housing so that it is conspicuous and easily removable.

Claims

1. A ground fault circuit interrupter 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;

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;

first and second sets 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 contact sets are closed and to selectively disconnect said input terminals from said output terminals when said contact sets are open;

a control circuit for causing said first and second contact sets 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 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 simulate an imbalance in current flow through said first and second conductive paths and thereby cause said control circuit to open said first and second contact sets; and

a removable barrier interposed between the contacts of the contact set that is connected to the output terminal other than that to which said test switch is connected, said removable barrier preventing a return current path from being established through the contacts of said contact set in response to actuation of said test switch under circumstances in which said AC source has been erroneously connected to said output terminals rather than to said input terminals.

2. A ground fault circuit interrupter as claimed in claim 1, wherein said test switch selectively connects said first output terminal to said second input terminal, and wherein said removable barrier is interposed between the contacts of said second contact set.

3. A ground fault circuit interrupter as claimed in claim 1, further comprising a third set of electrical contacts connected between a first power input of said control circuit and the AC source side of the contact set having said removable barrier, a second power input of said control circuit being connected to the AC receptacle outlet side of the contact set not having said removable barrier.

4. A ground fault circuit interrupter as claimed in claim 1, further comprising:

a manually resettable latching mechanism for maintaining said first and second contact sets in the closed state; and

an electrical solenoid operated by said control circuit for deactuating said mechanical latching mechanism to open said first and second contact sets.

5. A ground fault circuit interrupter as claimed in claim 1, wherein said removable barrier comprises a strip of electrically insulating material for preventing electrical conduction between said contacts when said contacts are closed.

6. A ground fault circuit interrupter as claimed in claim 1, wherein said removable barrier is provided with printed instructions for use by an installer of the ground fault circuit.

7. A ground fault circuit interrupter as claimed in claim 1, further comprising an indicator circuit connected between the one of said first and second output terminals to which said test switch is connected and the one of said first and second input terminals opposite in polarity to said output terminal, said indicator circuit including a visual indicator which is illuminated prior to removal of said barrier when said AC source has been connected to said input terminals and not to said output terminals.

8. An integral AC receptacle and ground fault circuit interrupter for protecting said receptacle, comprising:

a housing;

first and second terminals carried by said housing for connection to the line and neutral conductors, respectively, of an AC source;

a receptacle outlet carried by said housing for receiving an AC line cord plug, said receptacle outlet having first and second contacts which are electrically connected to said first and second terminals;

third and fourth terminals carried by said housing and electrically connected to the first and second contacts of said receptacle outlet, respectively, for optionally connecting said AC receptacle in parallel with a remote AC receptacle for which ground fault protection is desired;

first and second sets of electrical contacts for selectively connecting said first and second terminals to said first and second contacts, respectively, of said receptacle outlet when said contact sets are in a closed position and for selectively disconnecting said first and second terminals from said first and second contacts, respectively, of said receptacle outlet when said contact sets are in an open position;

a manually resettable latching mechanism for releasably latching said first and second contact sets in the closed position, said latching mechanism being actuated by a RESET pushbutton carried by said housing;

a control circuit for detecting an imbalance in current flow through the line and neutral sides of said receptacle outlet that is indicative of a ground fault condition at an AC load connected to said receptacle outlet;

an electrical solenoid operated by said control circuit for deactuating said latching mechanism to open said first and second contact sets;

a test switch for selectively connecting one of said first and second terminals to one of said second and first contacts, respectively, of said receptacle outlet in order to simulate an imbalance in current flow through said receptacle outlet and thereby cause said control circuit and said electrical solenoid to open said first and second contact sets, said test switch being operated by a TEST pushbutton carried by said housing; and

a removable barrier interposed between the contacts of the contact set that is connected to the contact of said receptacle outlet other than that to which said test switch is connected, said removable barrier preventing a return current from being established through the contacts of said contact set in response to actuation of said test switch under circumstances in which said AC source has been erroneously connected to said third and fourth terminals rather than to said first and second terminals.

9. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 8, wherein said test switch selectively connects said first contact of said receptacle outlet to said second terminal, and wherein said removable barrier is interposed between the contacts of said second contact set.

10. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 8, further comprising a third set of electrical contacts connected between a first power input of said control circuit and the AC source side of the contact set having said removable barrier, a second power input of said control circuit being connected to the receptacle outlet side of the contact set not having said removable barrier.

11. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 10, wherein said latching mechanism includes a movable latching member, and wherein said movable latching member forms a part of said third set of electrical contacts.

12. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 8, wherein said removable barrier comprises a strip of electrically insulating material for preventing electrical conduction between said contacts when said contacts are closed.

13. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 12, wherein said housing includes a front cover through which said receptacle outlet and said TEST and RESET pushbuttons are accessible, and wherein said strip extends through said front cover from the interior of said housing to the exterior thereof such that the exterior portion of said strip is visible to an installer of the receptacle.

14. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 13, wherein the exterior portion of said strip is provided with printed instructions for use by an installer of the receptacle.

15. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 8, further comprising an indicator circuit connected between the one of said first and second contacts of said receptacle outlet to which said test switch is connected and the one of said first and second terminals opposite in polarity to said contact, said indicator circuit including a visual indicator which is illuminated prior to removal of said barrier when said AC source has been connected to said first and second terminals and not to said third and fourth terminals.

16. An integral AC receptacle and ground fault circuit interrupter as claimed in claim 15, wherein said housing includes a front cover through which said AC receptacle and said TEST and RESET pushbuttons are accessible, and wherein said visual indicator is carried by said front cover so as to be visible to an installer of the receptacle.

17. A method for testing for improper wiring of an AC ground fault circuit interrupter receptacle having a pair of AC source terminals, a receptacle outlet connected to said source terminals, a pair of AC load terminals connected in parallel with said receptacle outlet, first and second latching contact sets connected in series between said source terminals and said receptacle outlet, a control circuit for releasing said contact sets to disconnect said source terminals from said receptacle outlet and said load terminals in response to a ground fault condition, and a test switch for simulating a ground fault condition by selectively connecting one of said source terminals to the one of said load terminals having opposite polarity, said method comprising the steps of:

latching said first and second contact sets;

temporarily open-circuiting at least one of said AC load terminals in order to prevent said test switch from simulating a ground fault condition when an AC source is connected to said load terminals rather than to said source terminals;

operating said test switch while said open circuit exists at said AC load terminal; and

observing whether the operation of said test switch causes said contact sets to be released.

18. The method of claim 17, wherein the step of temporarily open-circuiting at least one of said AC load terminals comprises the step of temporarily inhibiting conduction through the contact set connected to the AC load terminal other than that to which said test switch is connected, and wherein said method further comprises the step of restoring conduction through said contact set if operation of said test switch is observed to cause said first and second contact sets to be released.

19. The method of claim 18, wherein the step of temporarily inhibiting conduction through said contact set comprises the step of interposing a removable barrier between the contacts of said contact set.

20. The method of claim 17, further comprising the step of correcting an improper wiring condition by disconnecting an AC source from said load terminals and reconnecting said AC source to said source terminals in the event that operation of said test switch is observed not to cause said contact sets to be released.