US3699494A

US3699494A - Grounding connector

Info

Publication number: US3699494A
Application number: US80994A
Authority: US
Inventors: John T Thompson; George W Gillemot
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-15
Filing date: 1970-10-15
Publication date: 1972-10-17
Anticipated expiration: 1989-10-17

Abstract

A grounding assembly for use in completing a high strength solderless connection between conductive means and a grounding conductor supported in the earth, such as a pipe or stake. Either single or multiple solderless terminal units can be held captive adjustably along a single clamping band. The solderless terminal units can also be used alone or in multiple to provide assurance of a better and a higher capacity connection with the ground stake or pipe. These terminal units also include tempered sharp edges in high pressure contact with both the ground wire and the ground stake.

Description

Thompson et a1.

[54] GROUNDING CONNECTOR [72] Inventors: John T. Thompson, 244 Loring Street, Los Angeles, Calif. 90024; George W. Gillemot, 2331 20th Street, Santa Monica, Calif. 90405 [22] Filed: Oct. 15, 1970 [21] App]. No.: 80,994

[52] Cl. ..339/14 R, 339/251 [51] Int. Cl..... ..H01r 3/06, I-lOlr 13/24 [58] Field of Search ,....339/14, 251, 95; 174/40 CC, 174/78; 248/62, 74 B; 85/9; 24/278, 280, 281

I [56] References Cited UNITED STATES PATENTS 3,094,366 6/1963 Harmon ..339/97 2,083,606 6/1937 Johansson ..339/266 759,414 5/1904 Bishop ..339/251 X 3,129,994 4/1964 Harmon et a1 ..339/95 FOREIGN PATENTS OR APPLICATIONS 175,085 2/1922 Great Britain ..339/251 5 1 Oct. 17, 1972 348,736 2/ 1960 Switzerland ..3 39/251 509,264 1/1955 Italy ..174/40.1 834,091 5/1960 Great Britain ..339/251 Primary Examiner-Marvin A. Champion Assistant Examiner-Robert A. Hafer' Attorney-Sellers and Brace 57 ABSTRACT 19 C1aims, 8 Drawing Figures GROUNDING CONNECTOR This invention relates to devices for connectingelectrical equipment to the earth or a like source of zero potential, and more particularly to a solderless grounding clamp assembly for completing an electrical connection between a ground conductor and a stake or pipe having intimate contact with the earth.

It is of crucial importance that electrical equipment he safeguarded by a reliable and positive high capacity ground connection and commonly provided by means for completing a connection between a heavy gauge ground conductor and a water pipe or stake driven into the earth. Various expedients and proposals have been made heretofore for this purpose but these are lacking in reliability, ease of assembly, simplicity and ability to carry heavy currents should there be need. Usually the conductor to be grounded is a heavy gauge wire presenting handling difficulties and problems as respects bonding the same to a buried waterpipe or a ground stake. Desirably and customarily, the bonding accessory should be usable without resort to soldering, brazing or the like bonding expedients because of the adverse conditions customarily prevailing making it impractical or unfeasible to provide or utilize the high temperatures required to make a fused metal bond. It is therefore common practice to rely upon mechanical clamping means utilizing high pressures to assure good electrical contact. Such expedients have included a clamping band adapted to be contracted against a pipe or stake. Even though the band itself is placed under high tension, this does not assure sufficiently high pressure contact; between the band and the pipe to penetrate oxides and other poor conductive layers oftentimes present on the grounding member.

The foregoing and other shortcomings of prior art grounding practices and accessories therefor are avoided by the present invention which utilizes a high strength split clamping band in combination with means for holding one or more solderlessgrounding terminal units captively assembled thereto in such manner that tensioning of the band is highly effective in compressing sharp edged portions of the terminal assembly into high pressure contact with the grounded conductor. Either single or multiple solderless connector units are readily accommodated on the same clamping band without in any way decreasing its efficiency and effectiveness. Furthermore these solderless units may be used to provide multiple contacts with the grounding member using either the same clamping band or a second clamping band connected in parallel with the first. The solderless terminal memberper se is specially constructed and treated to make a high strength positive mechanical and electrical connection with the ground conductor as an incident to the anchorage of this member to the clamping band, this member comprising a high strength U-shaped metal strip tempered after formation and including sharp protruberances designed to penetrate into the ground conductor as the legs are pressed towardone another during the tightening of the connection to the clamping band. The solderless terminal unit includes a threaded shank securedto a channel-shaped member having sharp edged teeth or the like underlying the band and so positioned that tensioning of the band presses these teeth generally radially into the grounding stake or pipe causing the teeth to penetrate any oxide or coating on the pipe and, at the same time, enhancing themechanical anchorage tothe latter.

Accordingly, it is a primaryobject of 'the present invention to provide a highly versatile, improved, high-efficiency solderless grounding assembly for electrical equipment.

Another object of the invention is the provision of an inexpensive quickly and easily installed grounding connector for establishing a high-strength high-electrical capacity connection between a grounding conductor and a grounded conductive member.

Another object of the invention is the provision of a high strength clamping band having one or more solderless grounding terminal :units captively assembled thereto for use in completing a single or a tandem grounding connection between electrical equipment and a grounded conductor.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing inwhich a preferred embodiment of the invention is illustrated:

FIG. 1 is a fragmentary plan view of a grounded pipe or the likehaving an illustrative embodiment of the invention grounding clamp assembly installed thereon;

FIG. 2 is a cross sectional view on an enlarged scale taken along line 22 on FIG 1;

FIGS. 3 and 4 are fragmentary views taken along lines 3-3 and 4--4 on FIG 2;

FIG. 5 is a perspective view of a second embodiment of a component of the invention;

FIG. 6 is a cross sectional view similar to FIG. 1 but showing a plurality of the solderless terminal units installed on a single clamping band;

FIG. 7 is a perspective view of another mode of utilizing the invention clamping band; and

FIG. 8 is a perspective viewsimilar to FIG 7 but showing two of the grounding clamp assemblies installed in tandem on a grounding pipe.

Referring initially more particularly to FIGS. 14, there is shown a typical installation of the invention grounding clamp assembly, designated generally 10, comprising a splitclamping band 11 provided with a suitable adjustable take-up screw .12. This band is of the well known type wherein the deep thread of screw 12 projects into slots extending crosswise of one end of i the band at thepitch angle of the: screw thread. It will be understood that other types of clamping bands can be employed but this type is eminently suited for use in this invention because of its high strength and the high stress tension forces readily developed when tightening its adjusting screw.

Slidably supported lengthwise or circumferentially of band 11 is a generally channel-shaped wide area head 14 swaged, bonded or otherwise permanently fixed to a threaded shank 15. The inturned flanges integral with the opposite lateral edges of head 14 are proportioned to have a free sliding fit along band .11, as is readily apparent from FIG. 2. The inturned edges 17 of head 14 areforrned with serrations or sharp edged projections 18 which are preferably tempered to retain their sharp edges and capability of biting through oxides or other surface coatings frequently present onthe conductive grounding pipe or stake 20. As is made clear from FIG.

2, serrations 18 project radially inward toward the center of pipe 20 and their sharp edges sustain the major portion of the pressure applied by band 1 1 to the terminal unit as the clamping screw 12 is tightened.

The solderless terminal member preferably used with the above described components to provide a strong electrical connection between a heavy gauge grounding wire 22 and conductive member 20 comprises a U- shaped conductive member the resilient legs of which are widely diverted prior to assembly over shank 15.

vThis solderless terminal is disclosed in detail in our application Ser. No. 80,993, filed Oct. 15, 1970 being filed simultaneously herewith, and reference may be had to the disclosure thereof for a more detailed description. The bight portion 26 of the terminal member has an opening 27 sufficiently large to freely receive grounding conductor 22 and is located opposite the adjacent ends of semi-cylindrical channels 28 sized to snugly embrace the adjacent surfaces of conductor 22. Sharp pointed conical depressions 29 struck inwardly toward conductor 22 from the exterior side of channels 28 form sharp pointed conical protruberances projecting radially from the bottoms of channels 28. Member 25 is tempered after being formed in order that the protruberances will retain their sharpness for repeated use to penetrate into the same or other conductors 22. Preferably both legs of terminal member 25 are similarly processed with the results that the protuberances interlock with the conductor when the legs of the terminal member are compressed toward one another by the clamping nut 32 mounted over shank 15, the free ends of the legs being provided with aligned openings 33 seating freely over shank 15 in the manner best shown in FIGS. 2 and 3.

The assembly operation of the above described components will be readily apparent from the foregoing detailed description. The channel-shaped head 14 of shank 15 is assembled over one end of band 11 before it is engaged with the clamping screw 12. The open band is placed about the conductive grounding member 20 and the end of grounding conductor 22 is inserted through opening 29 at the bight end of terminal member 25. The latter member is then placed over the outer end of shank 15 and clamped tightly against the conductor by tightening nut 32. During the tightening operation the sharp protuberances are forced to bite into the conductor thereby assuring a good electrical connection as well as a positive solderless mechanical connection between the conductor and strip 25. Either prior or subsequent to tightening nut 32, screw 12 of the clamping band is tightened. As the band is placed under high tension a major portion of the forces acting in the band are transferred to the sharp serrations 18 on bolt head 14 with the result that these are forced to biteinto the underlying surface of pipe 20.

Referring to FIG. there is shown a variant of the clamping shank l5,-the channel shaped head 14' of which has slightly divergent side flanges 35 each formed with an elongated narrow passage 36 freely receiving the clamping band 11. This band is threaded through first one and then the other of passages 36 after which the free end of the clamp is engaged with clamping screw 12. So long as the clamp bands are held together by screw 12, it will be clear that shank l5 and integral head 14 are held positively and captively assembled to the clamping band. The edge of flanges 35 are preferably serrated as indicated at 18' and thereafter this head is tempered so that the serrations retain their sharpness indefinitely and throughout repeated assemblies to grounding members. It will therefore be clear that the threaded bolts shown in FIGS. 1-4 and 5 are usable interchangeably in the same manner and with the same bands.

Referring now to FIGS. 6 and 7 there are shown a plurality of the solderless terminal units assembled to a

common clamping band

11, 12. Each of these grounding units may be employed to anchor a separate ground conductor 22 to the pipe or certain of the solderless terminal members 25 may be used in the manner shown in FIG. 7 to interconnect the opposite ends of an auxiliary grounding conductor 40. The latter conductor is there shown as a short length of U-shaped heavy gauge wire having its oppositev ends firmly clamped in a respective one of the solderless terminal members 25 each of which is held closed and assembled to clamping band 11 by a respective one of the threaded shanks 15. One of these shanks is also used to anchor the ground wire 22 to clamp 11. This expedient provides additional grounding and current carrying capacity and greater assurance of high efficiency grounding connection to pipe 20. This is of particular importance in grounding heavy currents such as those sometimes encountered in the field and including lightning charges. Any deficiency which might be present between one of the bolt heads and the grounding pipe is assumed by conductor 40 and the solderless terminal assembly at the other end of this conductor.

FIG. 8 shows still another mode of utilizing the invention solderless grounding clamp assembly to provide heavier loadfcarrying capacity. According to this mode of use, two or more clamping bands 1 1, 11 are assembled to pipe 20 each carrying one or more grounding terminal units the shanks 15 of-which are electrically interconnected by a heavy duty conductive strip 42 here shown as having a series of holes 43 any pair of which may be selected to seat over shanks 15 As is true of the previously described modes of use, as many solderless terminal units as desired may be assembled to each of the bands 11 and these may be located closely beside one another or distributed to any position about the pipe 20 as may be desirable or suit the conditions existing in a particular environment.

While the particular grounding connector herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the detail of construction or design herein shown other than as defined in the appended claims.

We claim:

1. A solderless grounding clamp assembly comprising: split ring clamping band means provided with adjustable means for contracting said band means, threaded stud means having a head fixed to one end shaped to have a loose sliding fit circumferentially of said clamping band means and including sharp edges facing inwardly from the inner face of said band means for high pressure metal-to-metal electrical contact with rigid conductive means when said clamping means is tightly clamped thereabout, and solderless terminal means assembled over said threaded stud having sharp edged means thereon effective to bite into a grounding conductor as a clamping nut assembly to said stud is tightened thereby to complete a high strength mechanical and electrical connection between said stud and a grounding conductor.

2. A grounding clamp assembly as defined in claim 1 characterized in that said clamping band means includes a plurality of said threaded stud means slidably assembled and available for use to anchor electrical conductors thereto.

3. A grounding clamp assembly as defined in claim 2 characterized in the provision of a short length of conductor means having its opposite ends rigidly clamped to a respective one of a pair of said plurality of threaded stud means to provide supplemental grounding capability.

4. A grounding clamp assembly as defined in claim 3 characterized in that said short conductor means includes a solderless terminal at the free end of each end thereof effective to bite into and positively grip the conductor as nut means assembled over the ends of said pair of threaded stud means are tightened.

5. A grounding clamp assembly as defined in claim 1 characterized in the provision of a plurality. of said clamping band means each equipped with said threaded stud means adjustably supported thereon, and an interconnecting length of conductor means rigidly and electrically interconnecting said clamping band means in the assembled condition of said grounding assembly.

6. A grounding clamp assembly as defined in claim 1 characterized in that the head of said threaded stud means has inturned flanges spaced and shaped to loosely embrace the opposite lateral edges of the clamping band means to hold said head slidingly captive thereon.

7. A grounding clamp assembly as defined in claim 1 characterized in that the flanges of said stud head are provided with passages to receive said clamping band means which when tightened is effective to compress the edges of said flanges immovably into contact with a grounding conductor.

8. A grounding clamp assembly as defined in claim 7 characterized in that said passages have continuous rim edges whereby said clamping band means can be assembled thereto only by threading one end of said band means axially through said passages in succession.

9. A grounding clamp assembly as defined in claim 7 characterized in that the edges of said flanges are serrated to provide a plurality of sharp edges for penetrating into the surface of a grounding conductor as said band means is tightened and contracted thereagainst.

10. A grounding clamp assembly as defined in claim 1 characterized in that said solderless terminal means comprises a U-shaped tempered metal member formed from strip stock having an opening in its bight portion to freely receive a heavy gauge conductor as said con ductor is teleseoped through said opening, said U- shaped member having its legs shaped to partially embrace the latter from its opposite sides, and the ends of said legs having openings to fit over said threaded stud for clamping toward one another as said clamping nut is tightened.

11. A grounding clamp assembly as defined in claim 10 characterized in that said legs have tempered sharp edged protuberances projecting inwardly from the adjacent faces thereof effective to bite into the surface of a conductor as said legs are clamped thereagainst.

12. A solderless terminal assembly for grounding electrical conductors, said assembly comprising a tempered resilient U-shaped metallic strip having an opening through the bight thereof adapted to receive a conductor to be grounded, the legs of said strip diverging from one another prior to assembly to a conductor and stamped to provide shallow channels therealong facing toward one another with one pair of ends in communication with said opening and cooperating to clamp the opposite sides of a conductortherebetween assaid legs are pressed toward a conductor inserted through said opening, aligned openings through the free ends of said legs, a clamping bolt extending through said openings and having nut means thereon for compressing said legs toward one another as said nut means is tightened, and said bolt having a head fixed thereto thereon provided with a wide shallow passage adapted to loosely accommodate a pipe clamping band.

13. A terminal assembly as defined in claim 12 characterized in that the exterior end surface of said bolt head is formed with sharp hardened projections effective to bite into a grounded conductor when said head is compressed thereagainst by clamping band means.

14. A terminal assembly as defined in claim 12 characterized in that said bolt head is formed from flat stock and of generally C-shape as viewed from one end of said wide shallow passage, and said bolt head being permanently affixed to one end of said bolt.

15. A terminal assembly as defined in claim 14 characterized in that the opposed transverse ends of said C-shaped head are turned inwardly toward one another with the exterior surfaces thereof in alignment one with theother so as to bear against a grounded conductor with equal effectiveness as said head is compressed thereagainst.

16. A terminal assembly as defined in claim 15 characterized in that the exterior surfaces of the inturned ends of said C-shaped head includes sharp edged ribs adapted to bite into a grounded conductor as said head is compressed thereagainst.

17. A terminal assembly as defined in claim 14 characterized in that one end of the shank of said bolt extends through and is swaged permanently to the mid portion of said C-shaped head with the shank extending outwardly from and normal to the exterior surface thereof.

18. A terminal assembly as defined in claim 12 characterized in that the tempered legs of said U- shaped strip have sharp edged projections extending toward one another from the bottom of at least one of said channels and effective to penetrate into the surface of a conductor as said legs are compressed against a conductor end positioned in said channels.

19. A terminal assembly as defined in claim 12 characterized in the provision of adjustable clamping band means assembled loosely through the passage extending transversely of said bolt head with the bolt shank projecting radially outwardly from the exterior side of said band means.

Claims

5. A grounding clamp assembly as defined in cLaim 1 characterized in the provision of a plurality of said clamping band means each equipped with said threaded stud means adjustably supported thereon, and an interconnecting length of conductor means rigidly and electrically interconnecting said clamping band means in the assembled condition of said grounding assembly.

10. A grounding clamp assembly as defined in claim 1 characterized in that said solderless terminal means comprises a U-shaped tempered metal member formed from strip stock having an opening in its bight portion to freely receive a heavy gauge conductor as said conductor is telescoped through said opening, said U-shaped member having its legs shaped to partially embrace the latter from its opposite sides, and the ends of said legs having openings to fit over said threaded stud for clamping toward one another as said clamping nut is tightened.

12. A solderless terminal assembly for grounding electrical conductors, said assembly comprising a tempered resilient U-shaped metallic strip having an opening through the bight thereof adapted to receive a conductor to be grounded, the legs of said strip diverging from one another prior to assembly to a conductor and stamped to provide shallow channels therealong facing toward one another with one pair of ends in communication with said opening and cooperating to clamp the opposite sides of a conductor therebetween as said legs are pressed toward a conductor inserted through said openings, aligned openings through the free ends of said legs, a clamping bolt extending through said openings and having nut means thereon for compressing said legs toward one another as said nut means is tightened, and said bolt having a head fixed thereto thereon provided with a wide shallow passage adapted to loosely accommodate a pipe clamping band.

15. A terminal assembly as defined in claim 14 characterized in that the opposed transverse ends of said C-shaped head are turned inwardly toward one another with the exterior surfaces thereof in alignment one with the other so as to bear against a grounded conductor with equal effectiveness as said head is compresseD thereagainst.

18. A terminal assembly as defined in claim 12 characterized in that the tempered legs of said U-shaped strip have sharp edged projections extending toward one another from the bottom of at least one of said channels and effective to penetrate into the surface of a conductor as said legs are compressed against a conductor end positioned in said channels.