Universal strand clamp

Details Universal strand clamp Universal strand clamp

1999-05-13

2001-01-16

Sircus, Brian (Department: 2839)

Electrical connectors

With circuit conductors and safety grounding provision

Grounding to pipe, rod or conduit

C439S801000

Reexamination Certificate

active

06174177

ABSTRACT:

BACKGROUND OF THE INVENTION
Load carrying electrical cables generally induce an electrical charge on the messenger strands which are associated with such cables. For personnel and equipment safety reasons, the messenger strand must therefore be grounded at 4 to 5 locations over each mile of the cable run.
General purpose ground connectors have been utilized to provide an electrical connection between the strand and the ground conductor. However, these general purpose ground connectors have proved difficult to install and have not provided reliable connections due to the disparity in the outside diameters of the strand and the ground conductor.
Purpose-built strand connectors have also been used to electrically connect the ground conductor to the strand. Although these connectors provide a superior electrical connection between the strand and the ground conductor, they are sometimes difficult to install and are generally expensive to produce.
SUMMARY OF THE INVENTION
Briefly stated, the invention in a preferred form is a strand clamp for mounting a messenger strand to a ground wire. The strand clamp comprises a clamp assembly including first and second, substantially identical, clamp members. Each of the clamp members having oppositely disposed inside and outside surfaces where the inside surface of the first clamp member is positioned opposite to the inside surface of the second clamp member. A mid portion of each clamp member separates first and second side portions. First and second positioning tabs extend inwardly from the first and second end edges of each clamp member. The first positioning tab is laterally offset from the second positioning tab. The head of a bolt is positioned adjacent he outside surface of the first clamp member such that the shaft extends through openings in the mid portion of each clamp member. A nut is threadably displaceable on the threaded shaft of the bolt adjacent the outside surface of the second clamp member for clamping the first and second clamp members between the bolt head and the nut.
The first and second side portions each have a groove extending from the first end edge to the second end edge. The grooves of the first clamp member and the grooves of the second clamp member form a pair of receptacles for receiving the ground wire and the strand. Each of the receptacles has an arcuate engagement surface for clamping the ground wire and strand within the receptacle. The mid portion of each clamp member has an arcuate shape and is elastically compressible by the bolt and nut such that the mid portion imposes a spring force on the head of the bolt and the nut to resist loosening of the nut.
The strand clamp may also include a push nut which is mounted is on the shaft of the bolt adjacent the inside surface of the first clamp member to retain the bolt to the clamp assembly. The push nut has an opening and a plurality of tangs which extend obliquely into the opening. The diameter of the opening is greater than the diameter of the bolt shaft and the diameter defined by the inner tips of the tangs is smaller than the diameter of the bolt shaft. Inserting the bolt shaft into the opening causes the tangs to resiliently deform and apply a clamping force on the bolt shaft.
In a preferred embodiment, the opening of each clamp member has a substantially rectangular shape. In addition, the thread on opposite sides of the bolt shaft is removed to form a pair of oppositely disposed flattened surfaces and a pair of oppositely disposed threaded arcuate surfaces. The shape of the bolt shaft is complementary with the rectangular shape of the opening, thereby preventing rotation of the clamp members about the bolt shaft. Specifically, the pair of arcuate surfaces defines a distance Da and the pair of flattened surfaces define a distance Db, where Da>Db. The first pair of opposite surfaces of the opening define a distance Dc and the second pair of opposite surfaces define a distance Dd, wherein Dc>Dd, Dc>Da, and Da>Dd>Db.
An object of the invention is to provide a new and improved strand clamp for mounting the strand to a ground wire.
Another object of the invention is to provide a new and improved strand clamp which is less expensive to manufacture than conventional strand clamps.
A further object of the invention is to provide a new and improved strand clamp which has superior resistance to relative rotation between the two clamp members.
Other objects and advantages of the invention will become apparent from the drawings and the specification.


REFERENCES:
patent: 1420790 (1922-06-01), Varney
patent: 3610659 (1971-10-01), Gerarde
patent: 5055056 (1991-10-01), Auclair et al.
patent: 5816866 (1998-10-01), Langdon

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