US2683765A - Ground plate and connector - Google Patents

Description

July 13, 1954 F. H. LUE CKE GROUND PLATE AND CONNECTOR 2 Sheets-Sheet 1 Filed Dec. 16, 1948 Fig.

Zinnentor FREDERICK H. LUECKE in AW (Ittornegs y 1954 F. H. LUECKE 2,683,765

GROUND PLATE AND CONNECTOR Filed Dec. 16,- 1948 2 Sheets-Sheet 2 Snventor FREDERICK H. LUECKE Gttorneg:

Patented July 13, 1954 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to grounds and connectors therefor, and more particularly to a ground adapted to be buried in the earth, such as beneath a pole, and to a connector adapted to be utilized in connection with the ground of this invention, or with other types of grounds. The present application is a continuation in part of my copending application (now abandoned) Serial No. 757,361, filed June 2'7, 1947, for Electrical Grounding Device.

One of the early types of grounds is a rod, driven. for a suitable depth into the earth, and used in conjunction with lightning rods, at telegraph and telephone poles, substations, transformers, and other electrical installations. When an electrical ground is to be made in connection with a pole, such as to ground the circuits for safety, the length of rod required is usually much greater than the depth of hole dug to receive the butt end of the pole, and it is thus necessary, when using a single rod, to drive the rod farther down into the earth. When rocky earth is encountered, the difficulty in driving such a rod is often insurmountable. Also, for other installations, to provide an adequate contact area with the earth, a single rod is often required to be unduly long, or a large number of rods must be driven and tied together in multiple. A number of shorter rods requires an undue weight of metal, as well as producing complication in adequately connecting the rods to a ground Wire or the like.

Another type of ground for a pole, particularly a transmission line pole, is a circular butt plate, which is nailed or attached to the bottom of the pole, prior to its being placed in the hole in the earth dug for the same. A wire or connector extends from the butt plate up the side of the pole, and is usually nailed or otherwise attached to the pole. However, only one side of a butt plate is in contact with the earth, the efiective contact area of a butt plate thus being limited.

Among the objects of this invention are to provide a novel ground for electrical equipment or the like; to provide such a ground which can be placed in a hole or other area of limited extent; to provide such a ground which will provide an effective contact area greater than the cross sectional area of the space occupied by the ground; to provide a ground which is particularly adapted to be placedin holes dug for poles, but which may also be used in other places; to provide a ground which can be made in various forms, including a ground particularly useful for high frequently electrical equipment, such as radio or television equipment; to provide a novel connector for a ground; to provide such a connector which is particularly adapted to be in stalled on the ground of this invention; to provide such a connector which insures direct contact of a ground wire with the ground; to provide such a connector which will reduce the total number of connections, particularly intermediate connections; to provide such a connector which will accommodate wires of difierent diameter; to provide such a connector which need not be taken apart, but only loosened, for attachment of a ground wire or the like; and to provide such a ground and connector, each of which is sturdy in construction and will withstand considerable abuse, yet may be manufactured readily and relatively inexpensively.

Additional objects of this invention, and the novel features thereof, will become evident from the description which follows, taken in connection with the accompanying drawings, in which:

Fig. l is a three-dimensional view of a ground constructed in accordance with this invention;

Fig. 2 is a vertical section taken through the earth at a pole hole, illustrating a convenient installation of the ground of Fig. 1;

Fig. 3 is a top plan View of the lower portion of a modified form of the ground of Fig. l, particularly adapted for use in grounding high frequency electrical equipment;

Fig. 4 is an enlarged, fragmentary, transverse section, looking downwardly along the line 44 of Fig. 1;

Fig. 5 is an enlarged top plan View of a ground connector constructed in accordance with this invention, taken at the upper end of the ground of Fig. 1;

Fig. 6 is a similarly enlarged, front elevation of the'connector of Fig. 5 and an adjacent portion of a ground strap; and

Fig. '7 is an exploded, perspective view of the parts of the connector of Figs. 5 and 6, the adjacent portion of the ground strap, and a portion of the ground wire to be connected thereto.

As shown in Figs. 1 and 2, one form of the ground and connector of this invention may include a ground G which, instead of being attached to the butt end of a pole P, is placed beneath the pole in the hole i0, dug for the pole in the earth E. The ground G is provided with connecting means, such as a flat bar H, which extends upwardly in the hole It and to the upper end of which a ground wire it may be connected, as by a connector C, the latter also being 3 constructed in accordance with this invention. The ground G includes an electrically conductive strip it which is disposed on edge in the lower end of the hole 10, and extends laterally from bar ll. Strip I3 is formed of a suitable metal such as copper, prefedably being made from commercial bar, strap, plate or sheet stock, depending on the size, width and thickness required. The strip I3 may be circular, helical, or other desired shape as long as it is on edge, although in the preferred form it is generally annular and is provided with lateral configurations, such as-a series of equally spaced, outwardly extending portions, all but one preferably being triangularly shaped and having outer apices Hi and inner points I5, each of which may be rounded. Both the outer apices l6 and inner points [5.may be disposed in a circle, the outer circle having a suitable diameter, usually slightly greater than that of the pole P, but less than that of the hole l3.

One of thelaterally extending portions may be generall rectangularlyshaped, such as having sides to and lapped ends H, which conveniently comprise the ends of the strip 13. As used herein, the term triangularly shaped portions does not mean that these portions form a complete triangle, but may comprise only two sides of a triangle, while theterm rectanguarly shaped does notrequire the portion to form a complete rectangle, but may comprise only threesides thereof, some of which may slope slightly, somewhat in the nature of the inclined sides of a trapezoid. Also, the extending portions may have a any other desired shape.

the bar H'may be comiected together in a suitablemannen as by a rivet 18, or a number of rivets, while solder S -may be run around the joint and also to any desired extent between the ends 7 and bar H, to restrain access of ground water or moisture to the engaging surfaces of the strip l3 and bar H. 'The'bar H and strip ends 1? may also'be-welded orbrazed together.

The-ground'G of-Fig. 3 may be provided with a short circuiting wire or, rod 2|, which conveniently extendsfrom a point adjacent rivet l8 to r the apex M ofthe oppcsitelydisposed, generally triangularly shaped, laterally extending portion.

The ground G is otherwise constructed in a manner similar to the ground G, and is particularly adapted to be utilized in grounding equipment, such as used in radio or television work, in which relatively high frequency currentsare employed.

The effect of certain high frequency currents, when passing around a generally circular path,

apparently is to cause the generation of an harmonic or other variation of the frequency, which tends to pass back up through the bar II to the radio or television circuit, as I an interference wave. The wire or rod 2i divides this path into three components, one of unequal distance,-rather than twopaths of the same distance, thereby reducing the possibilit of setting up interference -waves.

As will be evident from Fig. 3, the ground G is generally star-shaped, the triangularly shaped" 4 extending portions being formed as the sides of equilateral triangles, with the adjacent sides which meet at an inner point [5 forming an angle which may vary with the diameter, one side being bent through IQ?" for a 10 inch diameter outer circle having seven triangular extending portions, as shown. However, the extending portions need not form equilateral triangles, nor need the side of each be a straight line, since various other shapes and configurations may be utilized, although a generally triangular shape is relatively easily formed, since a strip sufficient in length may be bent at successive points, to form the. exterior angle at an apex M, then the next inner,point l5, and so on. The angle between the sides It of the generally trapezoidal or rec- -tangular shapedextending portion and the adjacent triangular portion will usually differ slightly from the angle between adjacent triangular portions, while the extent of the lapped ends ll of the strip is preferably substantially equal to the width of the connecting bar H, althougheven these dimensions may vary. However, as indicated previously, advantages are obtained in so disposing the lapped ends ll that the connecting bar II will extend tangentially, since in that position it interferes least with the placement of the pole P in the hole Hi and the connection of the ground Wire thereto.

As shown in Figs. 5 to '7, inclusive, the connector C, constructed in accordance with this invention, may include a rear block 2 3 and a front block 25, each provided with a hole 26, while the upper end of the-bar II is also provided with a corresponding hole 26, for passage of a bolt 2! having alock washer 28 and a nut 28. The rear block 25 preferably is slightly lesser in width than the bar l I,- so that the edges 3% of the upper end of the bar may be bent, as in Figs. 5 and '7, to overlap the edges of the rear block. Also, the front block25 has a vertical groove 31 and the upper end of the bar I l is stamped or otherwise formed to provide a cooperating groove 32, so that the ground wire l2 may be inserted between the grooves 3| and 32, and clamped securely against the-bar II. 'The rear block 2 3 is also preferably provided with a groove S l, adapted to receive the rearwardly extending bulgeSE formed whengroove 32-is made in bar l, while a pair of indentations =33 are crimped or peened in edges 32] when the'connector C is installed, the indentations 33 extending into the rear block 24. The grooves BI and -32 are preferably arcuate in shape, and the front block 25 is preferably made of thicker material than the bar 8 i, so that when the clamping bolt 21 is tightened, the wire will be compressed into the strap groove 'Bi, thereby forming an extended area or" contact, providing a good electrical connection. The rear block 24 is also preferablyformed of thicker material than the bar II, so as to back up the bar l: and also permit 'a relatively heavy clamping pressure to be exerted against the ground wire i2. While blocks 24 and'2'5 are preferably made of thicker material than barll, they are preferably made of the same material,,so that expansion or contraction due to temperature changes is identical, thereby insuring a positive and tight connection at all times.

As willbe evident, when assembled for shipping, the bolt"2'l may be tightened, as in Fig.5, to hold the-connector C. securely on the end of bar ll. When the ground wire 12 is to be connected therewith, it'is'necessary .onlyto loosen bolt 2'i-slightly; i. 'e. 'a'sufilcientdistance to permit the wire l2 to be inserted in the grooves 3! and 32, after which the bolt 2! is tightened, to insure a firm, sound connection. As will also be evident, the rear block 24, by virtue of its groove 34 and the overlapping edges and indenta-' tions 33 of bar 1 I, does not tend to move from its position. Furthermore, it is unnecessary to remove any part of the connector C, and when wire i2 is inserted in grooves 31 and 33, the front block 25 is automatically aligned, so that the connector C has no tendency to require re-aligmnent or readjustment of any part in order to connect the ground wire thereto.

In installing the ground of this invention, in connection with a pole P, the hole I a for the ole is preferably made an inch or two deeper than otherwise. The ground G is placed in the bottom of the hole, and in soft earth, merely pressed in by a tamp or other suitable device. When in rocky ground, relatively finely divided earth is preferably tamped in around the strip 13. Also, in very dry earth, the finely divided earth may be treated with salt, blue vitriol, or other suitable material to insure that moisture will be retained in dry weather. The vertical or on edge position of the strip [3 is of considerable advantage, since a better contact can be provided, than if the ground were being placed from above on earth previously placed in the hole, as in the case of a butt p016 ground, which is nailed to the bottom of the pole, since there is no assurance of contact over the entire area of the plate on the bottom of the pole. The lower end of the pole need not be spaced above the bottom of hole it) to the extent indicated in Fig. 2, although such spacing is permissible. It is not objectionable to drop the pole directly onto the ground G, since with some earth around it, there is no possibility of damage or distortion. In fact, there is little possibility of damage or distortion when there is no earth around the ground G, since in compression tests, an 8 inch diameter ground constructed in accordance with this invention, formed of 1 inch wide strip copper .0625 inch thick, vithstood a compression load of 20,000 pounds, which is many times the weight of the heaviest pole which might be used.

The ground of this invention may also be installed apart from a pole, as in a hole dug for the purpose, to provide a ground for substation or other equipment, or at a radio or television station. Such a hole need not be as deep as that required for a pole, although a depth to or below the frost line is preferred, the length of bar H being correspondingly less. Also, a number of grounds may be buried in the same or separate holes. Such multiple grounds may be connected together in a suitable manner, the connector C also being adapted to be used in connecting a ground wire to a conductor, such as a strap leading from. bus bars, transformers, or other electrical equipment.

The preferred shape of the ground G of the present invention also provides a greater contact area, in proportion to the weight of material, than other accepted pole grounds. For in stance, in the case of a commercial ground constructed as shown in Fig. 1 and having an exterior diameter of 8 inches, the strip 13 is 43 inches long prior to bending, one inch high, and about .6625 inch thick. Allowing for one inch overlap, the contact area, on both sides of the strip, is about as square inches. A circular metal plate, adapted to be nailed to the bottom of the pole, which is 3 inches in diameter and has a thickness '6 of .0625 inch, will have only about 50.5 square inches of contact area, and yet has approximately 17% greater weight, i. e. requires 17% more material. When the connecting means or conductor II is considered, the relative contact area appears additionally more favorably. Thus, with a bar I I having a length of 66 inches and a width of 1 inch, a customary size, 132 square inches of contact area is added to the ground of this invention, but only 66 square inches to a pole butt ground, since the conductor is normally nailed to the pole, and only one side contacts the earth. In some instances, the ground wire passes down the pole, and is connected directly to the plate nailed to the bottom of the pole, but this createsa further disparity between the effective contact area of a pole butt ground so installed and the ground of this invention.

The common type of ground rod also has less total contact area and requires a greater weight of material. For instance, a inch diameter ground rod which is 8 feet long, a size commonly used, has an exterior area of about 188 square inches, whereas an 8 inch outside diameter ground constructed in accordance with this invention, formed of strip 1 inch wide, provided with a 66 inch connecting bar, has a total effective earth contact area of 216 square inches. In addition, the inch by 8 foot ground rod weighs over four times as much as the above 8 inch diameter ground of this invention.

The connector of this invention contributes not only to the effectiveness of the ground, but also may be utilized with other types of grounds. The efiective clamping of the ground wire or connecting wire, to a conductor or connecting bar, solves a problem of no small moment. A direct contact of the wire with the bar, and particularly in a groove into which the wire is pressed by con siderable clamping pressure, insures that an ade quate electrical connection wil1 be made. As indicatedpreviously, it is unnecessary to take the connector apart and the front block is automatically aligned by inserting the wire into the receiving grooves.

Little difficulty in manufacturing will be found, since the strip I3 is readily bent to shape, while the bar H is readily attached thereto. The connector C is also readily made and applied to th ground. The end of the connecting bar H, or any other conductor, is readily formed to provide the wire receiving groove 32 and bent edges 30, which overlap the rear block. Also, the front and rear blocks of the connector are each readily formed to provide merely a longitudinal roove and a bolt hole therein. As will be evident, the connector is adapted to receive wires of various diameters, since the wire is pressed into the material of the connecting strap, normally copper, which is more readily deformed than the thicker clamping blocks, while the wire itself will also tend to be flattened if slightly smaller in diameter than the receiving grooves.

The ground of this invention has received commercial acceptance. At the present time, there are only three types of grounds which are approved by the Rural Electrification Administration for use on REA lines. One of these is the conventional driven rod; another is the pole butt ground, of which several types are approved; and the third is the Groundmaster Starex, constructed in accordance with the present invention. Approval of the latter is contained in the notice which appeared on page 55 of the August 1948 issue of Rural Electrification Magazine, under the heading Additionsito approved 'materials list, in the following language:

The committee .unanimously accepted the following Starex grounds foruse as pole grounds:

Size,

Catalog No. inches It is significant to note that of quite a number of materials approved in'that issue (of which the Starex was the only pole ground), the ground of the present invention was the only one indicated as having been approved unanimously by the committee. Thecommercially manufactured grounds, constructed in accordance-With this invention, also meet the requirements of the U. S. Bureau of Standards, the Public Service Commission of Illinois, and other authoritative or regulating bodies. Such-approval, coupled With the novelty and uniqueness of the ground of the present invention, is believed indicative of a high degree of invention in the development of the present ground and connector therefor.

From the foregoing, it will b evident that the ground and connector of this invention fulfill to a marked degree the requirements and objects hereinbefore set forth. Also, although certain specific embodiments of the ground and connector have been disclosed-herein, it will be evident that other embodiments may exist, and that various other changes maybe made, all without departing from the spirit and-scope of this invention.

What is claimed is:

1. A ground for electrical equipment, comprisanelectrically conductive strip of uniform width but on edge andhaving a series of outwardly extending portions, one of said-portions being rectangularly shaped with slightly flaring sidesand the ends of said strip being lapped over toform the outer side of saidrectangularportion, and the remainder of .said portions being triangularly shaped with straight sides and rounded inner and outerrpoints, the said triangular. portions being contiguous to each other and ;the.said outer points and' inner pointsbeing disposed inrespectivecircles; an electrically con- .ductive bar at its lower. end disposed between said lapped strip encLsand extending upwardly therefrom; and a rivet extending through said lapped ends. and thereby'attaching said barand said lapped ends together.

2.v A ground for electrical equipment, as defined in claim 1,. including awire. extending from said rectangular portion adjacent said bar across to the outer point. of'a triangularportion opposite thereto.

References Cited in the file of this patent v.UNITED STATES PATENTS Number Name Date 357,050 Vail Feb. 1, 1887 414,943 Dewey Nov. 12, 1889 852,548 Finn May 7,1907 873,375 Jones .'Dec.'10 1907 883,303 Drake Mar. 31, 1908 1,288,303 iVogel Dec. 17, 1918 1,362,244 Farley "Dec. 14, 1920 1,878,257 Baker Sept. 20, 1932 1,891,920 'Eaton Dec. 27, 1932 2,303,861 'Pennell Dec. 1, 1942 2,308,528 Luecke 'Jan. 19 1943 2,309,607 Rogoff Jan. 25, 19 3 2,455,641 Badeau et a1 Dec. 7, 1948 2,556,956 'Benton et a1 June 12, 1951 FOREIGN I PATENTS Number Country Date 228,314 Switzerland Nov. 1, 1943 764,175 France Febp26, 1934

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