US2537463A - Ground rod construction - Google Patents

Description

Jam 9, 1951 A. A. HocHER ET Al. 2,537,463

y GROUND ROD CONSTRUCTION Filed Dec. 9, 1947 2 Sheets-Sheet 1 wqwcwvw 39a www Jan-9, 1951 f A,A.HOHER Em. 2,537,463

GROUND ROD CONSTRUCTION Filed Dec. 9, 1947 2 Sheets-Sheet 2 Fzgfj@ 253:50117 ffl/ 0.

LLLLLUL `Patented Jan. 9, 1951 Andrew A. Rocher, Glenshaw, anQRchard Gr. Robbins,- Pittsburgh, Pa., assignors to Hubbard and Companys, al corporation of Pennsylvania.

Application December 9, 194231 Scriailo. 790,635

(o1, ruf- 7 )Z x #.Claims.

This invention pertains torod structure for electrical grounding purposes, and particularly', to

improved connector arrangements there-for. One

phase of my invention deals with procedure` for making and assembling an improved' for-*1nv of groundrod.

Ground rods are employed with various types ofv electrical equipment and haveA awidefield of application in connection with electric transmission linesV and systems. Since it is cusironfiaryl to connect non-ferrous electric current conductors fcables or wires) to the ground rod, factors of corrosion, of obtaining and maintaining a good electrical contact, ofl avoidingV galvanic action, etc.; must -be considered along with questions of mechanical strength, cost, Simplicity or con-struction, etc.

Galvanicand'Y corrosive action are accentuated, since the ground rod and its connections are ord-inarily exposed to moisture and outside atmospheric conditions. As a result, ithas been customary to employ connections and rods both ofwhich are of a non-ferrous metal' such asl copper or copper weld (clad) steel'. However, a'. non-ferrousmetal is: much more er1-pensivel and. has. less mechanical; strength than a. lierrous metal.. latter characteristic of a non-ferrous metal is particularly disadvartageous,I since the ground rody is ordinarilydriven with` al Sledge into the ground for a sufficient distance to provi-dean allweather electrical connection with moist portions of the soil.

Since ordinary steel and iron- (ferrous metal) further augmented when an electrical connection is made, from a non-ferrous connector to a gal- Vanized'rod'. As a result, the industry does not favor the use. of ferrous rods and has built up a definite resistance against their employment.

As will be appreciated;` a good electric connection'must be at all times maintained between the non-ferrousv electrica] conductor, the connection and the ground rod il' the ground rod' installation is to serve its purpose. Rusting or corrosion between conducting surfaces produces a metallic oxide and galvanic action also produces various metal compounds whichy hinder the efficient transmission of an electric cu-rrent.

We have made the discoveryl that a galvanized ferrous metal rod can be successfully employed, and by reason of this discovery have been able to 2r open up an entirely new eld of ground rod utilization. Briefly. we have discovered that a galvanized rod may` be successfully employed without setting up objectionable galvanic or other type of corrosive action, particularlyv adjacent ferrous and non -ferrous conductingsurfaces, provided that such surfaces make apure metal-to- 'metal contact and are protected bythe natu-re of the construction, and also, provided that transmission of electrical current between a non-ferrous connector and a ground rod is not dependent on an interposed galvanized surface.

Homogeneity is a promoter of high corrosion resistance and one method of making certain of homogeneity is to use a pure base metal with no foreignl material which can separate, from the parent mass.

From the electromotive series (25n Ci), it appears that coppe-r has a positive potential of about 0.344,A iron has a negative potential of about 0.441', and zinc has a negative potential of about 0.762". It will thus appear that Zincv has almost ltwice as much of a negative potential as. iron.

This is one of the reasons that we wish to avoid dependence upon. the electrical conductivity of a contact between a galvanized coating and' a noni'errous connector to which an electrical conductor ,is to be connected or clamped, l

We also believe, that galvani'c' action between two electric-current-conducting surfaces of unlike metals such as iron which is; ordinarily anodic andrcopper which is ordinarily cathodic, Will' be increased bythe interpositi-oning of anotherv metal ofl higher potential therebetween, for example, zinc which is ordinarilyl anodic. That is, it is felt that a sacrificial corrosion of the zinc is eiected.Y A mass of corrosion product abnormal tothe composition of a base metal provides a very poor electricalv contact.

Tron, itself, tends'to corrode in the presence of oxygen to produce ferrous and ferr-'ic hyd-rox- Yides which are too coarse to be efficiently protective ofthe parentmetal. A metal such as zinc or a suitable zinc alloy isi anodic to iron and the iron is cathodc tothe zinc in the sense that it is protected thereby. Zinc not only protects the underlying or ferrous base metal, butv alsoby virtue of its chemical nat-ure, de'nitel-y protects the iron where itl i'sexposed by. smallA imperfections or fractures in the coating. Thus, we have determined that: in the manu-facture of a ground rod structure, we can obtain good protection of the ferrous base metal by the employmentA o-fa galvanized coating, even Where as set forth in a modied embodiment of our invention, we may lunder atmospheric conditions.

leave a small hair-like or fine line of exposure of the base metal adjacent to a non-ferrous connector, That is, we have been able to provide a demarkation between a galvanized coating of a ferrous base metal and a non-ferrous connector Which is mounted on the base metal portion of the ground rod, without providing an actual direct contact'between the galvanized surface and the non-ferrous connector.

We have for the first time provided a practical type of connection between a ferrous ground rod and a non-ferrous ground rod connector and have done so without the use of a complex, involved, or expensive fabricating or assembling procedure. In accordance with our invention, we have been able to obtain a pure metal-tometal, current-carrying contact between conducting surfaces of different base metal composition under conditions such that these surfaces are in eiect embedded and protected from atymospheric conditions, the interpositioning of a third metal between these surfaces is eliminated, and exposed surfaces have the maximum possible resistance to corrosive and galvanic action Since current will normally follow the path of least resistance, it will be apparent that electric current fiow between the ground and a conductor is substantially concentrated or centralized along a path representing these surfaces. This not only increases the efficiency of current conduction, but also minimizes galvanic action between other or exposed metal surfaces.

That is, in accordance with our invention, electricl current is conducted through what may be termed inner, closed-off or protected surface o r wall portions of the ground rod and the connector without reliance upon conducting properties of an adjustable clamping means (e. g. a bolt or nut) that is employed to secure the electrical conductor to the connector or its flange. We have been able to provide a substantially integral structural arrangement of highly elec-- `trically-conductive nature between a ground rod .and a conductor connector, have been able to` l eliminate sliding clamp connections with their inherent inefciency, and to eliminate .welded joints.

A welded type of `joint is disadvantageous in the first place in that considerable diiculty is encountered in properly welding ferrous and nonferrous parts of different melting points, and the homogenity of the metals is upset at the line of weld. There is always the question whether to use an alloy weld metal, or a weld metal representing one of the parts to be joined. Some scale or metal oxide tends to get into the `weld due to the action of oxygen on molten metal, thus decreasing the electrical-conducting efflciency of the weld; welding flux also tends-to lower its conductivity. It will thus appear that a weld joint is not the solution to the problem, since such joint, apart from its poor conducting properties, is somewhat porous and subject -to corrosive and galvanic action.

In accordance with a preferred method of our "invention, ground rods are fabricated from ordi- 'is preferred, since any desired thickness of coating may be provided, and such a coating is-relatively uniform and has an alloyed interface with 'the base metal.

After the galvanizing operation, we then tap the bore hole to remove the galvanized coating and the alloy interface, if there is one, to thus expose the base metal of the ground rod within the wall of the bore. In accordance with a modified procedure, we also grind off or otherwise remove the galvanized coating and any alloy interfacing on one or both sides of the rod about the bore hole to a diameter or to an area extent slightly larger than a corresponding diameter or area extent of a flange portion of the non-ferrous connector which is to be mounted in the bore of the ground rod. This ange, as will 'jbe appreciated, when in position against one side of the connector mount face of the ground rod, is in direct abutment with the base metal 0f the ground rod, and has a ne line of separation at its surface or outer periphery with respect to the galvanized coating of the ground rod.

The connector may comprise one or more` parts, and we prefer to have the primary part in a permanently mounted relationship Within the bore hole, so that it has a substantially pure metal-to-metal contact therealong and provides a maximum surface contact. Such primary part of the connector is also preferably flanged over at its opposite ends, and at at least one end thereof,

to seal off the surface portions of such connector part that closely abut adjacent surfaces of the base metal wall of the bore of the ground rod. One flange also serves as a clamping flange against which an electrical conductor may 'be secured by adjustable clamping means.

Although it is believed that our invention solves a definite problem in the art, in that it makes possible the practical utilization of a ferrous ground rod, as distinguished from a nonferrous ground rod, the form of connection between the ground rod and the conductor is also new in itself and is advantageous in connection with any type of ground rod, such as a nonferrous copper or copper-weld rod. If a copperweld rod is employed, the threaded bore may expose the copper coating or the ferrous metal core, in that the problem of three unlike metals is not involved.

It has thus been an object of our invention to discover and evaluate the factors which have, heretofore, limited the utilization of ferrous ground rods and to provide a practical solution for the problem presented thereby;

Another object of our invention has been to provide new and improved procedure for making ground rods and/or for mounting an electrical connectoron a ground rod;

A further object of our invention has been to devise a new and improved form of ground rod structure or construction;

A still further object of our invention has been to provide a less expensive, highly electricallyeffeient, wear-resistant, and simplified form of ground rod construction. l

These and many other objects of our invention will appear to those skilled in the art from the description, the` illustratedv embodiments and the appended claims.

In the drawings:

Figure l is a front View in elevation of a rod constructed in accordance with our invention;

Figure 2- is a fragmental side view in partial section of the rod of Figure l;

ground rod` structure in an assembled relation.- ship asy constructed in accordance with. our in,- vention and embodying the fornr of` ground rod shown particularly in Figures 1 2;

Figure 4- is a detail of. a clamping element taken in the direction of line IV-IV of Figure. 3;. A

` Figure 5 is a reduced front fragmental view illustrating a modified type of ground rod constructed in accordance. with` our invention;` Figure 5A is a view similar to. Figure .2, as' applied' tothe ground rod of Figure 5; Figure 6 is a side sectional viewiin elevation, taken longitudinally alongV a connector part or sleeve-like stem element that` may be utilized with the ground rod of Figure 5A;

Figure 7 is. a side fragmental. View in partial section showing how the connector partof Figure 6 may be assembled within the rod of. Figure 5A;

Figure 8V is a view to Figure 3, but shows a complete assembly employing the; struc.- ture of Figure '1;

Figure 9 is a side view and Figure l0' is an end View of a modiied form oi clamping bolt that may be employed with an assembly such as shown in Figure 7;

Figure 1l is a View somewhat similar to Figure 8, but illustrates a. modified form of connector sleeve part, the utilization of the clamping. bolt of Figures 9 and 10, and theV utilization of. a ground rod shape similar to Figure 1,;

In Figures 1. to .11, inclusive, We have illustrated preferred procedure for making ground rod structures in accordance with our invention; and, in Figures 12 to V17, inclusive, we have shown a slightly modied procedure as applied, to the structuralv embodiments of Figures 3, '7, and 11.

More specically, Figures 12, 13,` and 14 correspond somewhat to Figures 1,A 2,- and 3; Figures 15 and 16 correspond somewhat to Figures 5 and 7; and,A Figure 1.7' correspondssomewhat-toFigure 11,` with the connectorl boltremoved.

In practicing our invention, vve rstfabricate aground rod part. of ,ferrous metal by any suitablemethod such asa forging method and provide it with a drivingaolown. head portion, a connector mou-nt or attened portion,I and a: pointed or driving end portion.v After a bore hole has been. provided in the connector mount to give it aneye by any suitable method, such as punching, cutting, or drilling, the rod thus formed isthen hot dipped, electrolytically treated, or by suitable conventional procedure provided with a galvanized coating of a metaL such as Zinc or afzinc alloy.. In accordance with this procedureywalls of the bore of the connector mount portion of the rod are then tapped or threaded out. in such a manner as to expose the ferrous. base metal of the rod.

The connector of ourl structure isv fabricated and is inserted to extend within the bore of the mount portion of the rod and is securely mounted therein in such a manner thatv its major surfaces are in a direct, somewhat-compressed contact or tight abutment with the pure metal bore surfaces or walls of the ground rod. In accordancelr with one structural embodiment of our invention, the connector comprises a primary sleeve-like ste-m ,part which is inserted within the bore oi the rod, andV a secondary stern or bolt which is inserted in thev primary stem and is adapted to be adjusted with respect thereto to clamp an electrical conductor thereagainst. In accordancefwith another and preferred embodiment of our invention, a bolt-like connector stem part, itselfr is mounted within and in an efficient,

electricallyeconductive abutment. or contact with the exposed pure metal bore of the rod.

The connector and its. parts are preferably of a nonferrous metal such as copper or a copper alloy correspondingr substantially' in nature to the electrical conductor which is. to,` bev used.- If an aluminum, conductor is to be used, then itis preferably to employ an aluminum or an aluminum. alloy connector which may comprise a boite-like stem, clamping. anges and a sleevelike stem, the latterI is. used., .Howeven it Will be apparent, as far as eiiicientl electrical conductivity is involved, that partsV ofthe connector (other than the stem part in contact with the bore of the ground: rod) may be of.` any suitable metal,` since the conductor 2l tightly clamped against the integral frontv flange. of the: part thereof, which is secured Within the bore of the ground rod After a connector stem part has been inserted within the bore of the ground rod, .the back end thereof may then be peened-over or upset. 'to se,-v curely' lock it in position between the back: ange thus formed and. an integral iront clamping flange thereoi,l see for example, the. bachiiange i8 and the front or conductor-clamping flange ii of the embodiment of Figure 3;,

It will thus be: apparent that in accordancel with our invention, an inexpensive ferrous-metal galvanized ground' rod mayv be. employed which will withstand rough usage, and particularly, Sledge hammer blows in driving itv into the ground,` and will at the same time,l have an efficient electricalconducting connection with a conductor. The connector is sealed. or closed oil from. moisture, etc., at its principal ground-rod abutting surfaces. Y Y

Referring tol the. embodiments shown in the drawings, and particularly, to the preferred embodiment of Figures 1 to 3, inclusive, wehave shown a metal ground rod i5 having a driving head portion Il, a driving end portion i2, and a flattened eye or connector mount portion lf3. In Figure 1, line a indicates the location of. the bore which is cut or punchedy out of the mount portion I3'.

Figure 1 th-us illustrates steps in forming the ground rodl. Figure 2 shows the. rodafter such operations have been effected and its bore has been tapped or threaded, see Iffi. Figure 3 illustrates the provision. ofv a non-ferrous connector I5 having a stem i6 provided with male threads la, an integral clamping flange 11 and an extending back end which is peened over or upset to provide a back langei8, after its threaded stem has been fully enteredV within the threaded bore l of the'mount I3.. Its front and back iianges l1 and I8 are in close abutment with the front and back,l galvanized metal surfaces or faces of the mount I3.

In the embodiment of our invention shown in' Figure, the connector has a bolt-like stem elementor part I5 provided with threads ld which cooperate with threads M of the bore hole. A threaded clamping nut i9 and ay clampingV flange 29 are adjustably mounted on the front, longitudinally-extending or projecting portion of the connector to securely clamp a conductor .ZV

against the integral clamping fiange l'l. That is', vthe front'fiange ll extends transversely of the connectorlE and is positioned in a close, sealing 01T abutment with the front side or face of the mount portion I3, and with the back iange la, eiectively seals off wall portions of the borev of the rod. As shown particularly in Fig'- ures 3 and 4, the non-ferrous clamping washer 2D is of somewhat rectangular shape with cut oi corners and has` inwardly cr backwardly extending or inclined bent edges d, e, f, and g which provide a series of four, spaced, clamping, and positioning edges for the conductor 2 I. The clamping Washer 20 thus has an coto-edge shape.

InV the embodiment of our invention shown in Figures 5, 5A, 6, and "I, the ground rod I9 is provided with a shorter length driving head I I and an intermediate connector mount portion I3 which is located adjacent the driving portion II. In this embodiment, the tapped bore or eye Wall I4 is adapted to receive a connector or primary sleeve-like noneferrous stem part 2% which is threaded internally at 2l and externally at 30 and is provided With an integral front flange 26. The portion 29 of the stem is introduced into the tapped bore I4 and tightly secured in such a manner that its front or clamping flange 25 closely abuts the galvanized surface or face of the mount portion of the rod IB. The extending end of the portion 29 is then upset in such a manner, see Figure 7, as to provide a back flange 28 which abuts a corresponding, galvanized surface or face of the mount portion of the ground rod I. The flanges 26 and 2B thus seal or close off the base metal walls or surfaces of the bore I4 of the ground rod I as Well as surfaces of the connector part 25 which are in close abutment therewith.

In Figure 8, We have shown the construction of Figure '7 with a secondary bolt-like connector stem part 'I5' which is provided with threads I5a, in order that such part may be adjustably positioned within the inner or female threads of the primary part 25. The connector part or element I5 is provided with a clamping nut, Wrench flat ork clamping flange I9 which is adapted to clamp a conductor 2I against the integral front flange 26 of the primary stem part 25.

In the embodiment of our invention shown in Figures 9, 10, and 11, We have discloseda modiiied form of primary connector part or nonferrous element 25 which has a shorter length and is upset at its back end to provide a flange 28 within an outwardly oifset o1' cut out portion h of the bore of the ground rod I0. In forming the bore hole of the mount portion I3 of the ground rod, the cut out portion h is provided after the galvanizing operation, or as a part of the tapping operation. Although this type of ground rod structure may employ any suitable form of secondary connector part such, for example, as I5 of Figure 8, it has been shown as employing an element 36 having threads 31. As shown in Figures 9 and 10, the part 3B has a mushroom-like head 38 that extends transversely and backwardly thereof to provide clamping edge portions 39a and 392). Such portions have inner concave conductor-receiving faces for the conductor 2l. If desired, the secondary conductor part 35 may be provided with a locking nut 39 that is adjustably mounted on its back end and may be tightened into abutment with the back iiange 28 of the primary part 25.

In Figures 12 to 17, inclusive, We have employed the same numerals for structure which has been previously described in connection with Figures 1 to 16, inclusive, but have added the numeral b to Figures l2 to 14, inclusive, to indicate the extent of removal of the galvanized coating Ia from a planar back face or surface of the mount portion I3 and the numeral c to indicate the extent of removal of the coating from a planar front face or surface of such mount portion. In the embodiment of Figures 15 and 16, the numerals b' and c' are used for the same purpose; and, in the embodiment of Figure 17, the numeral c is used to indicate the extent of removal of the coating from the front face or surface of the mount I3.

In accordance withY the procedure of these latter igures, the galvanized surfaces of the ground rod mount are removed about the bore hole, as by grinding them off, to expose the ferrous base metal of the rod. The diameter or width of the coating-removing action is limited in extent to substantially correspond to the maximum diameter of flange,fupset, o'r peened portions of a connector which is to be used therewith.

By Way of illustration, it will be noted that the diameter or area extent of the face c corresponds substantially to the diameter or area extent of the clamping flange I1 and that the diameter or area extent of the iiange head I8 corresponds substantially to the diameter or extent of the pure metal face b, but that there is a small line of demarkation between the edges of the coating Ita and the outer or peripheral edges of the flanges I'! and I8. That is, the galvanized coating Illa on one planar surface or face of the connector mount portion I3 rof the rod terminates at the outer edge of b and on the other planar face or side terminates at the outer edge of c, see Figure 1, in such a manner that the closing or sealing ofi spaced-apart anges I8 and I1 are in close adjacency to the coating Ita and in a spaced relationship from terminating edges thereof.

Although we prefer to galvanize a ferrous metal ground rod before mounting a connector thereon, the galvanizing may be effected after the connector stem has been secured within the bore or centrally positioned eye portion of the ground rod. In such a case, the galvanized coating should at least, be removed from the integral clamping flange face of the connector stem against which the conductor 2I is to be secured. In this connection see the flange I'I of Figure 1, the iiange 23 of Figure 8 and the flange 26' of Figure 1l.

As will be noted particularly from the illustrated embodiments of my invention shown in Figures 1 to 4, inclusive, and 12 to 14, inclusive, I have provided a metal ground rod Ii] having a longitudinally-eXtending, rod-like, integral body whose lower pointed drive portion I2 extends longitudinally for facilitating driving it into the ground, and whose upper driving end portion II extends longitudinally from the upper end of its integral body and terminates in the mount portion I3 of novel design. This ground rod was devised to meet a particular problem in the art, namely to meet the need for a directly driven type of ground rod of good mechanical strength which has better corrosion resistance and electrical conducting properties. Its up-set-forged mount portion I3 that is on its integral body has a pair of radially bulged-out or rounded somewhat circular sides of greater diameter than the adjacent rod-like portions of its integral body. Such mount portion I3 also has a pair of substantially flattened or planar front and back side faces of substantially the same diameter as the adjacent `portions of its rod-like integral body (see Figures 2 and 13). 'Y -e 'eye portion If'4 lis substantially centr-ally positioned in its lmount portion I3 vand -extends transversely through the front Aand back faces of suoli mount portion :and exposes the ibase -metal .of the integral body along its `eye Wall. The non-ferrous connector stem part I5 has -a front abutment flange I1 extending integrally-'radially from its intermediate portion and'also integral stud portionsla and I 6 extending from opposite sides -of ythe front abutment flange I1 .and provided withmale `threads thereon or thereabout. One `stud portion 15a is permanently mounted to extend through the eye portion M valong its eye wall in engagement with the female'threads thereof and in a direct electrical contacting relation with the base metal of the rod body. A back face of the front abutment flange I1 is positioned in a close sealing-olf abutment with the front side face kof the mount portion I3 and the up-set. back abutment flange I8 extends integrally-radially from the end of the stud portion I5a and has a front face in close, sealing-olf abutment with the back side face of the mount portion I3. The other stud portion I6 projects outwardly from the front abutment flange I1, and the clamping nut I9 is adapted to be adjustably mounted on its threads to secure the non-ferrous conductor 2| tightly against the front face of the front abutment flange I1. The clamping washer 2B is adapted to be positioned on the stud portion I6 between the flange I1 and the nut I 9 and has, as shown particularly in Figure 4, the series of peripherally spaced-apart, backwardly bent edge portions d, 6,'1, and g which `serve to guide the conductor 2l, prevent it from being turned or loosened, and thus hold it in a secure position against the front face of the front abutment flange I1.

Although we have shown embodiments of our invention for the purpose of illustration, it will be apparent to those skilled in the art that various modifications, additions, and subtractions may be made to the structure and procedure shown without departing from the spirit and scope of our invention, as indicated by the appended claims.

What we claim is:

1. An improved ground rod that is adapted to be driven into the ground by blows applied to its upper end, said rod having a longitudinally-extending rod-like integral body of a base metal having good mechanical strength, a pointed drive portion at the lower end of said integral body for facilitating driving said rod into the ground, an up-set-forged mount portion yon said integral body having a pair of radially bulged-out sides of greater diameter than adjacent rod-like portions of said integral body and having a pair of substantially flattened front and back side faces of substantially the same diameter as adjacent portions of said rod-like integral body, a substantially centrally positioned eye portion extending transversely through the front and back side faces of Asaid mount portion and exposing the base metal of said integral body along` its eye wall, female threads extending about and along the eye wall of said eye portion, a driving head portion at the upper end of said integral body and extending upwardly from said mount'portion, a non-ferrous connector stem part, a front abutment flange extending integrally-radially from an intermediate portion of said connector stem part, integral stud portions extending from opposite sides of said front abutment flange and having male threads thereabout, one of Asaid stud portionsbeing mounted to extend ythrough said eye' portion along its eye wall i-n engagement with the female threads thereof and in a direct electrical' contacting relation with the base metal of said body, a back face of said front yabutment flange being positioned in lclose sealingoif abutment with `thefront side -face of said mount portion, an -up-'set back abutment -'flange extending integrally-radially from ran end of said one stud portion and having a front face in close sealingoff abutment withA `fthe back Aside .face of said mount portion, the other of said stud portions projecting outwardly from said front abutment ilange, and a clamping nut adapted to be adjustably mounted on the threads of said other strd portion-to 4sec-ure -a non-ferrous conductor tightly against a front face of said front abutment flange.

2. An improved ground rod that is adapted to l be driven into the ground by blows applied to its upper end, said rod having a longitudinallyextending rod-like integral body of a ferrous base metal having good mechanical strength, a pointed drive portion at the lower end of said integral body'for facilitatingdriving said rod into the ground, an up-set-forged mount portion on said integral body having a pair of radially bulged' out sides ofA greater diameter than adjacent rodlike portions of said integral body and having a pair of substantially flattened front and back side faces of substantially the same diameter as adjacent portions of said rod-like integral body, a substantially centrally positioned eye portion extending transversely through the front and back side faces of said mount portion and exposing the ferrous base metal of said integral body along its eye wall, female threads extending about the eye wall of said eye portion, a driving head portion at the'upper end of said integral body and extending upwardly from said mount portion, a non-ferrous connector stem part, a front abutment flange extending integrally-radially from anintermediate portion of said connector stem part, integral stud portions extending from opposite sides of said front abutment flange and having male threads thereabout, one of said stud portions being mounted to extend transversely through said eye portion along its eye wall in engagement with the female threads thereof and in a direct electrical contacting relation with the base metal of said body, a back face of said front abutment flange being positioned in close sealingoff abutment with the front side face of said mount portion, an up-set back abutment flange extending integrally-radially from an end of said one stud portion in close sealing-oil abutment with the back side face of said mount portion, the other of said stud portions projecting outwardly from said front abutment flange,Y a protective non-ferrous metal coating on the ferrous base metal of said integral body, and a clamping nut adapted to be adjustably mounted on the threads of said other stud portion to secure a non-ferrous conductor tightly against a front face of said front abutment flange. Y

3. An improved ground rod as defined in claim 2 wherein, the non-ferrous protective coating terminates closely adjacent to the back face of said front abutment ilange, and the base metal of said body at said mount portion is directly exposed to abutting back and front faces of said front and back abutment flanges.

4. An improyed ground rod as dei-ined in claim 2 wherein, a clamping Washer is adapted to be positioned on said other stud portion between said 11 front abutment flange and said 'clamping nut and has a series of peripherally spaced-apart back- Wardly bent edge portions to guide the non-ferrous conductor and hold it in a secure position against the front face of said front abutment flange.

' ANDREW A. HOCHER.

RICHARD G. ROBBINS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Brewer Mar. 13, 1906 Number Number Number 35 316,336

Germany Nov. 27, 1919

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