Swivel ground clamp for bare armor wire

A ground fitting allows electrical connection between a ground wire carried in a metal sheathing, and a ground point such as a water spigot on a short pipe extending from a wall. The pipe clamp is tightened on the short pipe or ground rod. The metal sheathing is cut to expose a short length of ground wire. The ground wire is inserted into the wire clamp, and the metal sheathing is inserted between a clamping plate and clamp seat at the near end of the wire clamp. A ground screw is tightened against the ground wire to hold the ground wire in the wire clamp and plate screws securing the clamping plate are tightened to secure the sheathing between the clamping plate and clamp seats. The wire clamp is attached to the pipe clamp selectively parallel or perpendicular to the short pipe or ground rod to compete the ground fitting.

BACKGROUND OF THE INVENTION

The present invention relates to electrical grounding and bonding, and more particularly to a ground fitting for easily grounding or bonding a ground wire carried in spiral metal sheathing (e.g., an armored cable) at an endpoint to a pipe extending a short distance from a wall.

Ground wires frequently require protection from damage. The ground wire is generally a heavy gauge wire, for example eight gauge or six gauge solid, or four gauge stranded, and is generally uninsulated. A common method for protecting a ground wire is to carry the ground wire in a spiral metal sheathing (e.g., armored cable), thereby creating an armored ground wire. Such spiral metal sheathing provides the desired protection to the ground wire.

It is often necessary to connect the ground wire to a ground member (or ground point) such as a water spigot extending from the side of a structure. Unfortunately, known grounding clamps do not allow the clamp to be attached to the pipe between the wall and spigot, and allow the ground wire to be attached in the most desirable manner parallel to the wall to keep the ground wire close to the wall.

Therefore, a need remains for a ground fitting (or clamp) and method of use which clamps to a spigot pipe and facilitates running the ground wire parallel to the wall for the entire length of the ground wire.

BRIEF SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by providing a ground fitting which allows simplified electrical connection between a ground wire carried in a metal sheathing, and a ground point such as a water spigot on a short pipe extending from a wall, or to a ground rod. The ground fitting comprises a wire clamp and a pipe clamp. The metal sheathing is cut and a short length removed to expose a short length of ground wire. The ground wire is inserted axially into the wire clamp, and the end of the metal sheathing carrying the ground wire is inserted axially between a clamping plate and clamp seat at a near end of the wire clamp. A ground screw is tightened against the ground wire to hold the ground wire in the wire clamp and plate screws securing the clamping plate are tightened to secure the sheathing between the clamping plate and clamp seats. The pipe clamp is tightened on the short pipe or ground rod, and the ground clamp is attached to the pipe clamp parallel to the short pipe or ground rod, or perpendicular to the short pipe or ground rod.

In accordance with one aspect of the invention, there is provided an end point ground fitting. The ground fitting includes a wire clamp and a pipe clamp. The wire clamp includes an armored cable entry, an armored cable clamp, a ground cable passage, and a ground wire screw. The armored cable clamp comprises a clamp seat facing a clamping plate for sandwiching the armored cable end inserted into the armored cable entry. The clamp seat and the clamping plate include interior concave dished portions including interior ridges for engaging an exterior spiral surface of the armored cable to retain the armored cable end in the armored cable entry. The ground wire passage allows axial inserting of the ground wire into the ground wire passage. The ground wire screw intersects the ground wire passage and is approximately perpendicular to the ground wire passage to intersect and thereby clamp the ground wire in wire clamp. The pipe clamp and the wire clamp include cooperating faces providing four attaching alignments allowing the ground cable to be aligned either parallel to, or perpendicular to, the short pipe.

In accordance with another aspect of the invention, there is provided a method for connecting an armored ground wire to a short pipe carrying a spigot. The method includes: attaching a pipe clamp to the short pipe; cutting a short length of the metal armored cable sheath surrounding a ground wire to expose a short length of the ground cable, axially inserting the exposed ground wire into a ground cable mouth of a wire clamp while inserting the armored cable end between a clamping plate and clamp seat at the near end of the wire clamp; tightening a wire clamp screw to grip the ground wire in place in the ground wire passage, tightening the armored cable clamp screws to grip the armored cable end between the clamping plate and clamp seat; and attaching the wire clamp to the pipe clamp with the ground wire perpendicular to the short pipe. Tightening the armored cable clamp may comprise tightening the clamping plate to sandwich the armored cable end between a concave dished portion of the clamping plate and clamp seat and intersecting at least one ridge on the concave dish portion with exterior spiral surfaces of the armored cable end to retain the armored cable end in the wire clamp. In one embodiment, ridges are provided on both the clamping plate and clamp seat to further secure the end of the metal sheathing sufficiently to meet code requirements.

DETAILED DESCRIPTION OF THE INVENTION

An armored (or sheathed) ground wire30suitable for use with the present invention is shown inFIG. 1. The armored ground wire30is generally protected by an armored cable sheath32. formed from a metal spiral allowing flexing while protecting the ground wire34inside the armored cable sheath32.

FIG. 2Ais a side view of a ground fitting10according to the present invention connecting a sheathed ground wire30to a short pipe16reaching from a wall11to a spigot13, a front view of the ground fitting connecting the sheathed ground wire30to the short pipe16is shown inFIG. 2B, and a top view of the ground fitting10connecting the sheathed ground wire30to the short pipe16is shown inFIG. 2C. The ground fitting10in comprised of a two piece pipe clamp14comprising a top portion14aand a bottom portion14b, and a cable clamp12. The pipe clamp14is fixed on the short pipe16by tightening two screws24. Details of the pipe clamp14are disclosed inFIGS. 3A - 5Bbelow. The wire clamp12is attached to the pipe clamp14by screw19and includes an armored cable sheath clamp portion21and a ground wire clamp portion17. The ground wire34is held in the ground wire clamp portion17by screw18, and the armored cable sheath32is held in the armored cable sheath clamp portion21by a clamping plate20. The pipe clamp14has a pipe clamp centerline14′ and the wire clamp12has a wire clamp centerline12′.

A top view of a pipe clamp top portion14aaccording to the present invention is shown inFIG. 3A, a front view of the pipe clamp top portion14ais shown inFIG. 3B, is a rear view of the pipe clamp top portion14ais shown inFIG. 3C, an end view of the pipe clamp top portion14ais shown inFIG. 3D, and a cross-sectional view of the pipe clamp top portion14ataken along line4-4ofFIG. 3Ais shown inFIG. 4. The pipe clamp top portion14aincludes a pair of downward facing grooved surfaces15awhich are tightened against the short pipe16to hold the pipe clamp in place. Two vertical screw passages24aon opposite sides of the pipe clamp top portion14aprovide passage of the screws24. The screw passages24areside in recesses42aand42b. A mouth44opens one of the recesses24aallowing the pipe clamp to be positioned on the small pipe16without completely removing the screws24. The raised center of the pipe clamp top portion14aincludes screw passage19bcentered in a rectangular platform with recessed cross shape second mating surface40afor attachment of the wire clamp12.

A bottom view of a pipe clamp bottom portion14baccording to the present invention is shown inFIG. 5Aand a front view of the pipe clamp bottom portion14bis shown inFIG. 5B. The pipe clamp bottom portion14bincludes threaded holes24baligned with the holes24ato receive the screws24to tighten the pipe clamp on the small pipe16. The pipe clamp bottom portion14bincludes a pair of upward facing grooved surfaces15bwhich are tightened against the short pipe16to hold the pipe clamp in place.

A side view of a wire clamp12according to the present invention is shown inFIG. 6A, an end view of the wire clamp12is shown inFIG. 6B, a top view of the wire clamp12is shown inFIG. 6C, and a bottom view of the wire clamp12is shown inFIG. 6D. The wire clamp12includes a raised arch38having a ground wire passage36for entry of the ground wire34, and a threaded screw passage19afor the screw19allowing the screw19to be tightened against the ground wire34inserted into the ground wire passage36. A slightly raised entry portion23on the near (to the ground wire) end of the wire clamp includes a curved seat52bfor cooperation with the clamping plate20forming the armored cable sheath clamp21to sandwich the armored cable sheath32. Threaded screw passages22breceive the screws22to tighten the clamping plate20. The curved seat23amay include two shallow ridges50b(seeFIGS. 7A-8) to engage the armored cable sheath32.

The wire clamp12includes a downward facing horizontal cross first mating surface40bfor cooperation with the recessed cross shape40bon the pipe clamp top portion14afor attachment of the wire clamp12to the pipe clamp top portion14a. A screw passage19ais provided for the screw19to secure the wire clamp12to the pipe clamp top portion14a. The cross shape of the horizontal crosses40aand40ballow the wire clamp to be positioned in any one of four directions for routing the sheathed ground wire30.

A top view of a clamping plate20according to the present invention for holding the armored cable sheath32. is shown inFIG. 7A, a side view of the clamping plate20is shown inFIG. 7B, and a cross-sectional view of the clamping plate20taken along line8-8ofFIG. 7Ais shown inFIG. 8. The clamp plate20includes concave dished portions facing the concave clamp seat23aand the plate20includes a shallow ridge50ainside the concave dished portion52aturned slightly away from the direction of the ground wire passage36and approximately aligned with an exterior spiral surface of the armored cable sheath32. for engaging the exterior spiral surface of the armored cable to retain the armored cables ends in the armored cable entries. Previous apparatus for clamping armored cable ends has failed to meet new electrical requirements requiring, for example, the clamping to hold under 50 pounds of tension. The combined ridges50aand50bsignificantly increase the force required to pull the armored cable sheath32. out of the ground fitting10thereby meeting the new requirements. The ridges extend approximately 0.035 inches from the concave dished surface to engage the armored cable.

A front view of the ground fitting10according to the present invention attached to a ground rod60is shown inFIG. 9Aand a top view of the ground fitting10attached to the ground rod60is shown inFIG. 9B. Ground rods60are generally eight or ten feet long with one foot exposed above ground62. The ground fitting10allow convenient attaching the armored ground wire30to the ground rod60with the armored ground wire

The screws18and24and the clamping plates20are preferably zinc coated steel, and more preferably have a minimum approximately 0.001 inch thick zinc coating. The ground wire grasping portion12and the ground point plate14are preferably made of a copper alloy and are more preferably approximately 80 percent copper. The screws22are preferably 10-24 stainless steel screws for additional strength.