Electrical ground protection device, circuit tester and method of circuit condition detection

• US 8,339,270 B2
• Filed: 12/21/2007
• Issued: 12/25/2012
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: General Wire Spring Co.
• Original Assignee: General Wire Spring Co.
• Inventors: Silverman, Arthur A., Pfeiffer, Anton D.
• Primary Examiner(s): Lee, Benjamin C
• Assistant Examiner(s): KING, CURTIS J
• Application Number:
  US12/004,701
• Publication Number:
  US 20090160663A1
• Time in Patent Office: 1,831 Days
• Field of Search: 340/650
• US Class Current: 340/650
• CPC Class Codes: H02H 11/001 in case of incorrect or interrupted earth connection disconnection by breaking of earth connection H02H5/105
• CPC Class Codes: H02H 11/002 in case of inverted polarity or connection; with switching for obtaining correct connection
• 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 5/105 responsive to deterioration or interruption of earth connection for preventing switching-on H02H11/001

Abstract

An apparatus and method for protecting against electrocution hazards that arise when an appliance is electrically connected to a miswired single-phase AC electrical source which includes an energized ground lead are described. The apparatus includes one or more sensors that detect electrical energy in the ground lead combined with a miswiring condition in the hot and common leads. A tester embodiment is also illustrated. The method includes the steps of detecting if the putative ground of the electrical source is energized and whether the hot and common leads are reversed.

Claims

1. An electrical circuit for detection of improper wiring of a three lead power supply, having leads of equal resistance, comprising:

a sensor circuit for detecting the absence of electrical current in a putative hot lead of said three lead power supply;

a sensor circuit for detecting the simultaneous presence of a source of electrical current in both of the putative ground lead and putative neutral lead of said three lead power supply;

wherein the putative ground lead is in electrical communication with the putative neutral lead, causing the putative ground lead to be electrified as well

an independent ground circuit in electrical communication with said sensor circuits for directing electrical current from said sensor circuits to earth; and

an indicator circuit for generating a unique response signal specifically indicating the absence of electrical current in the putative hot lead, simultaneously with the presence of a source of electrical current in said putative ground and neutral leads, said indicator circuit being formed, in part, by said independent ground circuit and utilizing an independent power source to generate said unique response signal.

2. An electrical circuit as described in claim 1, wherein said response signal triggers the termination of electrical continuity in at least one of the three leads.

3. An electrical circuit as described in claim 2, wherein said response signal triggers the termination of electrical continuity in the ground lead.

4. An electrical circuit as described in claim 2, wherein said response signal triggers the termination of electrical continuity in all three leads.

5. An electrical circuit as described in claim 1, wherein said response signal triggers at least one sensory indicator selected from the group consisting of a visual indicator and an audible indicator.

6. An electrical circuit as described in claim 1, wherein said circuit is incorporated into the power supply circuitry of an electrically powered device.

7. An electrical circuit as described in claim 1, wherein said circuit is incorporated into a test device comprising a plug for insertion into an electrical outlet and at least one sensory indicator.

8. An electrical circuit as described in claim 7, wherein said response signal triggers at least one sensory indicator selected from the group consisting of a visual indicator and an audible indicator.

9. An electrical circuit as described in claim 1, wherein said sensor circuit for detecting the presence of electrical current in a putative ground lead of said three lead power supply further comprises a probe circuit which is mounted adjacent a ground pin for insertion into an electrical outlet.

10. A method for detection of improper wiring of a three lead power supply, having leads of equal resistance the method comprising:

detecting the absence of electrical current in a putative hot lead of said three lead power supply;

detecting the simultaneous presence of a source of electrical current in both of the putative ground lead and putative neutral lead of said three lead power supply for therein;

wherein the putative ground lead is in electrical communication with the putative neutral lead, causing the putative ground lead to be electrified as well

introducing a second, independent source of power and independent ground circuit; and

generating, utilizing said independent source of power and independent ground circuit, a unique response signal specifically indicating when, in the as-wired condition, the absence of electrical current is detected in the putative hot lead simultaneously with the presence of a source of electrical current in both of said putative ground and neutral leads.

11. A method as described in claim 10, wherein generating said response signal triggers the additional step of termination of electrical continuity in at least one of the three leads.

12. A method as described in claim 11, wherein generating said response signal triggers the additional step of termination of electrical continuity in the ground lead.

13. A method as described in claim 11, wherein generating said response signal triggers the additional step of termination of electrical continuity in all three leads.

14. A method as described in claim 10, wherein generating said response signal triggers the additional step of initiating at least one sensory indication selected from the group consisting of a visual indication and an audible indication.