Compact ground clamp

A ground clamp having upper and lower clamp members interconnected by clamping screws for mechanical and electrical connection with a grounding member, and a frontally projecting boss on the lower clamp member having a downwardly opening slot for receiving a ground wire which is retained by a set screw forward of the clamping screws whereby the various screws may be independently tightened without interference from adjacent screws.

FIELD OF THE INVENTION

The present invention relates to electrical connectors for ground wires and, in particular, a ground clamp for connecting a grounding wire to a parallel grounding member.

BACKGROUND OF THE INVENTION

Grounding connectors are used to electrically connect electrical devices to a grounding members, such as ground rods, pipe and rebar. Inasmuch as the connectors are typically installed underground or in limited access space, the compactness and ease of use are primary concerns. One prior art device for connecting a grounding wire to a parallel grounding member includes a pair of clamp members that are interconnected by clamping screws for clamping the ground member therebetween. A block is provided on the top clamp member having a transverse through hole for receiving the grounding wire. A vertical set screw is provided for clamping the grounding wire in the block. The upper vertical location of the block increases the overall envelope size of the ground clamp, in both the packaged and installed conditions. Such ground clamps are also disposed in serial locations along a grounding member. As it is desirable to use a continuous length of grounding wire, the grounding wire needed to be successively threaded through the block hole, a time consuming installation step.

The serial installation problem was partially overcome by the clamping apparatus for connecting ground wire to grounding member disclosed in U.S. Patent Application Publication No. US2004/0092142. Therein, as shownFIG. 7, the ground clamping apparatus100includes an upper clamp102connected to a lower clamp104by screws106to clamp a ground member therebetween. Instead of a hole through the block108on the upper clamp, an upwardly opening slot110is provided. Accordingly, the ground wire may be laid in the slot and a transverse set screw112tightened to clamp the ground wire in the slot. While assisting in the installation of the ground wire, the position on the upper block still increased the mounting envelop size. Further, the set screw and the clamping screws were in a common plane. To gain tool access to one of the clamping screws for uniform clamping, the set screw had to be in a retracted position in the ground wire block, otherwise the shank of the set screw physically interfered with took access to the clamping screw. For subsequent installation ground wire, the set screw had to be loosed and thereafter retightened, presenting an additional installation step. After ground wire attachment, the clamping screw was once again overlaid by the set screw, creating operational problems if the ground clamp needed repositioning or retightening.

SUMMARY OF INVENTION

The present invention provides a compact ground clamp for interconnecting a ground wire to a grounding member wherein upper and lower clamp members are attached by clamping screws for engaging the grounding member and wherein a ground wire boss projects forwardly from the lower clamp member and includes a downwardly opening slot that receives the grounding wire, which is clamped thereto by a set screw located in a plane axially spaced from the clamping screws. The forward and bottom axial position of the boss overcomes the above limitations of prior ground clamps by providing a more compact packaged and installated assembly, avoiding interference between the ground wire set screw and clamping screws, and allowing the set screw to be packaged in a retracted position to allow direct ground wire installation.

Accordingly, it is an object of the invention to provide a ground clamp that is more compact than current devices, both as packaged and installed.

Another object of the invention is to provide a ground clamp that avoids interference between the fasteners for connecting the grounding member and the ground wire.

A further object of the invention is to provide a ground clamp having a lay in ground wire mounting that can be conveniently accessed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to theFIGS. 1 and 6, there is shown a ground clamp10for establishing a grounding relationship between a ground wire12connected with electrical devices to be grounded, and a buried parallel grounding member14, such as rebar, pipe or ground rod.

The ground clamp10comprises an upper clamp member20connected by threaded clamping screws22to a lower clamp member24for clamping the grounding member14therebetween. The lower clamp member24includes a slotted ground wire boss26carrying the ground wire12, which is releasably clamped therein by set screw28. The clamp members are conventionally formed of suitable conductive material such as copper alloys. The ground clamp is configured to handle a customary range of ground wire and grounding member sizes. The range for the ground wire would typically be #10 through #2. The clamp would typically accommodate rigid conduit, copper tubing, and rebar from ⅜ inch to ¾ inch diameter.

Referring toFIGS. 2 through 5, the upper clamp member20includes an inverted V-shaped center section30having a downwardly opening transverse groove31laterally bounded by end sections32,33having rounded ends. The inclined and top inner surfaces of the groove32of the center section30include transverse ribs34for accentuating mechanical and electrical contact with the grounding member14in assembly. The end section32includes a vertical through hole35for slidably receiving the shank36of the screw22. The end section33includes a forwardly opening slot38, for slidably receiving the shank36of the other clamping screw22and permitting rotation of the upper clamp member20about the end section32in preliminary assembly. An upwardly projecting tang39is formed on the top surface of the end section33adjacent the outer side of the slot38. The tang39engages the head40of the clamping screw22to function as a stop thereby preventing relative clamp member rotation in preliminary and final assembly.

The bottom clamp member24includes a truncated V-shaped center section42having an upwardly opening groove44laterally bounded by end sections46,48with rounded ends and underlying the end sections32,33of the upper clamp member20in assembly. The end sections46,48include threaded holes registering with the hole35and the slot38of the upper clamp member20for threadably receiving the shanks36of the clamping screws22.

The boss26projects axially from the front of the center section42of the lower clamp24. The boss26has a top surface coextensive with the base of the groove44. The boss26includes a downwardly opening transverse J-shaped slot54bounded by side walls56,58and parallel to the grooves in the clamp members. The inner surfaces of the side walls56,58are laterally spaced to form a downwardly opening slot entrance for permitting insertion of ground wires of common sizes. The side wall56includes a recessed semicircular inner wall. The side wall58includes a curvilinear inner wall merging the inner wall of side wall56. The side wall58is laterally tapped for receiving the threaded shank of the set screw28. As shown inFIG. 3, the set screw28has an axis in a vertical plane60forwardly spaced a distance “D” from the vertical plane62of axes of the clamping screws22at a sufficient distance to allow independent access to the tool slots without interference. In packaged condition, the set screw may be furnished in a retracted position thereby allowing direct insertion of the ground wire into the J-slot, without initial retraction of the set screw.

For assembly, the clamping screws22are unloosened sufficiently for allowing the lower clamp24to engage the grounding member14and the upper clamp20to pivot about the clamping screw on end section32with the other clamping screw entering the slot38for rough assembly. Thereafter, the clamping screws are tightened progressively to a clamped position against the ground member24, with the tang39preventing subsequent rotation a the slot. With the set screw28in a retracted position, the ground wire12is inserted upwardly into the J-slot and held against the recess. The set screw28is then tightened to clamp the ground wire against the side wall54. Should subsequent repositioning or retightening of the screws be required, the same may be done independently with interference.

It will be appreciated that the clamp of the present invention, in both the installed and packaged condition, presents a compact clamp envelope in comparison with the prior art clamp ofFIG. 6.

The above description is intended to be illustrative of the preferred embodiment, and modifications and improvements thereto will become apparent to those in the art. Accordingly, the scope of the invention should be construed solely in accordance with the appended claims.