This invention relates generally to devices for implementing a ground connection between an electrical meter box and a common ground point. More particularly, the present invention relates generally to clamp devices which mount to an electrical meter box and connect via a flexible conductor with a common ground point.
A number of various types of devices have been employed for connecting a ground wire with an electrical meter box. Most conventional devices employ clamp assemblies of various forms. In applications to which the present invention relates, the connecting devices are ordinarily clamped onto the exterior of the electrical meter box which is mounted on the wall of a building.
A number of conventional designs are configured to mount rigidly or semi-rigidly onto the electrical meter box. For such designs, damage to the electrical meter box can occur when the clamping force is applied to the electrical meter box. For example, it is not uncommon for the electrical meter box to be bent or twisted when the clamping force is applied.
In another known design, the device clamps onto a corner of the electrical meter box. A lower flange of the device engages a bottom skirt of the electrical meter box top cover. A bolt threadably disposed through a top plate of the device engages the electrical meter box top cover. Applying a torque to the bolt causes the device to be clamped to the electrical meter box. Such devices may not provide an adequate electrical connection with the electrical meter box.
A ground clamp disclosed in U.S. Pat. No. 6,329,592 includes a U-shaped clamp member having first and second legs which form a slot. A pair of openings in the first leg form a center segment disposed between two fingers. The edge portion of the meter box enclosure is resiliently clamped within the slot between the fingers and the second leg. The center segment includes a threaded socket. A bolt member has a stud portion and a bolt head portion, the stud portion including a threaded segment disposed proximate the distal end and an unthreaded shaft segment disposed intermediate the threaded segment and the bolt head portion. At least one protrusion extends axially from the distal end of the bolt member to a sharp edge. The stud portion is mounted in the socket of the clamp member such that the shaft segment is positioned in the threaded portion of the socket and the threaded segment is positioned within the slot when the sharp edge of the protrusion contacts the exterior surface of the edge portion received within the slot. The sharp edge of the protrusion removes the corrosion inhibiting coating from the exterior surface of the edge portion to electrically connect the meter box to the clamp without deforming the meter box enclosure upon rotation of the bolt member. However, a hammer or similar tool is usually required to insert the second leg of the clamp member between the bottom skirt of the meter box top cover and the side or front panel of the meter box.
Briefly stated, the invention in a preferred form is a meter box ground clamp for clamping a ground wire to a metallic meter box. The meter box ground clamp comprises a U-shaped clamp body, a wedge body, a bolt member and a ground engagement bolt. The clamp body includes first and second leg segments and a base segment, the base segment and leg segments forming a vertically extending, open channel. Each of the leg segments has a laterally extending upper extension segment. The base segment has a lower portion having a vertically extending slot, a middle portion, and an upper portion having an opening and extending at an angle from the middle portion into the channel. The wedge body includes an upper segment disposed proximate to the clamp body legs, a lower segment disposed proximate to the clamp body base segment, and a middle segment extending substantially horizontally from the lower segment, through the slot of the clamp body base segment, to the upper segment. The wedge body upper segment has a substantially triangular shape. The wedge body lower segment has a substantially cylindrical lower portion having a sidewall defining an axially extending bore and a laterally extending threaded opening. The wedge body middle segment has a vertically extending, axial threaded opening. The bolt member includes a bolt head disposed above the upper portion of the clamp body base segment, and a shaft extending downwardly from the bolt head through the opening of the upper portion of the clamp body base segment, at least a portion of the shaft having a threaded surface threadably engaged with the opening of the wedge body middle segment. The ground engagement bolt includes a bolt head, and a threaded shaft extending from the bolt head. The threaded shaft is received within the threaded opening of the wedge body lower segment and is threadably displaceable therein to clamp a ground wire positioned within the bore of the wedge body lower segment. The extension segments of the clamp body legs are adapted for engaging the exterior surface of the drip cap and the bolt member is adapted for threadably driving the wedge body upper portion into the meter box overlap joint such that the wedge body upper portion mechanically engages the abutting surfaces of the edge portion of the meter box drip cap and the upper end portion of the meter box panel to electrically connect the ground clamp to the meter box.
The upper portion of the wedge body lower segment includes first and second laterally extending wings. The width of the wings and the width of the base edge of the wedge body upper segment are each greater than the width of the slot of the clamp body base segment, such that the wedge body is retained to the clamp body while allowing vertical movement of the wedge body relative to the clamp body. The wedge body upper segment extends at an obtuse angle (γ) from the wedge body middle segment and the wedge body lower segment extends at a right angle (α) from the wedge body middle segment. Preferably, angle γ is substantially equal to 96° and angle α is substantially equal to 90°.
The front and rear faces of the wedge body upper segment have a wedge-shape profile, widening from the upper tip to the bottom edge. Preferably, the front and rear faces of the wedge body upper segment form an angle substantially equal to 6°. The front face of the wedge body upper segment has an abrading surface, formed by multiple serrations. Preferably, each of the serrations has a depth substantially equal to 0.005 inches and forms an angle with the base edge substantially equal to 68°.
Each leg segment has upper, middle and lower portions, with the extension segment extending laterally from a front edge of the middle portion. The extension segment includes a front portion having a downwardly extending tooth, for penetrating the corrosion inhibiting coating on the meter box drip cap.
An object of the invention is to provide a new and improved ground clamp for implementing a ground connection between an electrical meter box and a common ground point.
Another object of the invention is to provide a new and improved ground clamp for use with an electrical meter box that is easily installed.
A further object of the invention is to provide a new and improved ground clamp which is inexpensive to manufacture.
Other objects and advantages of the invention will become apparent from the drawings and specification.
The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawings in which:
With reference to the drawings wherein like numerals represent like parts throughout the several figures, a meter box ground clamp in accordance with the present invention is generally designated by the numeral 10. As shown in
With reference to
The base segment 34 has a longitudinal axis 40 and upper, middle and lower portions 42, 44, 46. The middle portion 44 has a generally circular opening, preferably disposed axially therein. The lower portion 46 has a longitudinally extending slot 48, preferably disposed axially therein. The upper portion 42 of the base segment 34 extends from middle portion 44 into channel 38 between the first and second leg segments 36, 36′ and has a substantially circular opening 50, preferably disposed axially therein.
Preferably, upper portion 42 and middle portion 44 form an angle substantially equal to 90°.
Each leg segment has upper, middle and lower portions 52, 54, 56. The upper portion 52 includes an extension segment 58 that extends laterally from the front edge of the middle portion 54. The front portion of the extension segment has a tooth or prong 60 that extends downwardly from the lower edge 62, the rear edge of the prong 60 and the front edge of middle portion 54 define a gap 64. Preferably, the rear edge of the prong 60 substantially perpendicular to lower edge 62 and the front edge extends at an acute angle from the rear edge, forming a sharp point.
With reference to
When viewed from the side, the lower segment 70 has an arcuate-shaped upper portion 86 and a substantially cylindrical lower portion 88, the upper and lower portions 86, 88 sharing a common wall section 90. First and second wings 92, 92′ extend laterally from the side edges of the upper portion 86. A threaded opening 94 extends through the sidewall 96 of the lower portion 88. Preferably, the opening 94 is positioned substantially opposite the common wall section 90 and substantially on the axis of the wedge body 14. The lower portion 88 may be formed by bending first and second arms 98, 98′, extending laterally from the sides of the common wall section 90, to form a bore 100, with the distal end portions 102 of each arm 98, 98′ overlapping and opening 94 extending through each distal end portion 102.
The wedge body middle segment 68 extends substantially horizontally from the upper segment base edge 72 to the lower segment upper portion 86. An axial threaded opening 104 extends vertically through the wedge body middle segment 68. Preferably, the wedge body upper segment 66 extends at an obtuse angle γ from the wedge body middle segment 68 and the wedge body lower segment 70 extends at right angler a from the wedge body middle segment 68. Preferably angle γ is substantially equal to 960 and angle α is substantially equal to 90°.
With additional reference to
With reference to
With reference to
With reference to
It should be appreciated that the abutting surfaces 142, 144 of the drip cap lip portion 30 and the top portion 32 of the panel 26, 28 are not coated with paint, to allow the spot welding operation that joins the drip cap 24 to the panels 26, 28. Therefore, the metal-to-metal contact between clamp body prongs 60 and the drip cap 24 and between the wedge body upper segment 66 and drip cap lip portion surface 142 and panel top portion surface 144 provide an excellent conductive path for grounding the meter box 22. The abrading surface provided by the serrations 84 on the front face 80 of the wedge member upper segment 66 removes any coating (e.g. surface corrosion, surface contamination, etc.) on the panel top portion surface 144 that might otherwise interfere with the electrical connection between the ground clamp 10 and the meter box 22.
After the ground clamp 10 is mounted to the meter box 22, a ground wire 20 is inserted into the bore 100 of the wedge body lower segment 70 and the ground engagement bolt 18 is torqued to clamp the ground wire 20 therein. A gel-filled boot 146 may be inserted over the upper portion 148 of the clamp body 12 (
With reference to
While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustration and not limitation.
Number | Name | Date | Kind |
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2420895 | Merriman | May 1947 | A |
4106832 | Burns | Aug 1978 | A |
4784621 | Auclair | Nov 1988 | A |
4828504 | Franks, Jr. | May 1989 | A |
5556299 | Finke | Sep 1996 | A |
5746609 | Franks, Jr. | May 1998 | A |
5928006 | Franks, Jr. | Jul 1999 | A |
6329592 | Auclair | Dec 2001 | B1 |
6494726 | Auclair | Dec 2002 | B1 |
6572390 | Ladin | Jun 2003 | B2 |
6857881 | Balfour | Feb 2005 | B1 |