FR2617338A1 - METHOD, DEVICE AND GROUNDING PIN - Google Patents

Abstract

The invention relates to a process for grounding an electrical installation by electrical connection of the latter to a grounding device (1) comprising a metal rod (2) pushed vertically into the ground (3) and connected to a conductive cable (4) connected to the electrical installation to be protected. The terminal portion (4a, 4b) of the cable (4) is bare or stripped and its end is fixed at the lower extreme part of the said rod (2) especially in the vicinity of its point of penetration (5), so that the said terminal portion (4b) of the said cable is extended along the rod over the entire buried length of the latter and is in continuous, intimate, direct contact with the surrounding terrain (3) over the entire length of the said terminal portion of the cable (4) thus interred. The invention is applicable to the protection of electrical power distribution or transmission networks and of electrical machines or systems.

Description

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  The present invention generally relates and relates essentially to a method of grounding an electrical installation that may comprise for example a transmission or distribution network of electrical energy or electrical machines, to ensure its protection and security of particularly by grounding the masses to allow the flow of occasional or accidental electrical fault currents, as well as a grounding device for carrying out this process and, as a new and improved industrial product, a picket

  earth intended to be used in such a device.

  The invention also relates to the various applications and uses resulting from the implementation of the method and / or the device and / or the aforementioned stake and the systems, apparatus, equipment, arrangements and materials provided with such devices and stakes. It is already known, for example by the publication No. 2,476,920 of the French patent application No. 80.04084, a grounding device for grounding an electrical installation by electrical connection thereof by means of a conductive connection cable with an electrode of adequate length, preferably substantially vertical, driven into the ground and in direct intimate contact therewith. This electrode is constituted by a rectilinear metal post with direct vertical drive substantially in particular by threshing, connected to a conductive cable connected to the electrical installation to be protected. This known peg comprises at least one open longitudinal recess extending from the upper end of the peg to the vicinity of its lower end penetration point, this peg being in particular profiled to uniform cross section to

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  regular regular symmetrical configuration comprising radially protruding longitudinal ribs or ribs and angularly spaced uniformly or equidistant delimiting between them, respectively, recessed dihedral grooves. This shaped peg is preferably cruciform right cross section and optionally selectively elongate being composed of several sections that can be assembled end-to-end to each other by connecting members such as intermediate coupling sleeves each of which is nestable by its opposite ends respectively

  on the neighboring ends of two successive sections.

  In its service configuration in the set state, this peg emerges or protrudes permanently above the ground by its upper end which thus remains external to the ground and the conductive cable is fixed to this external upper end or exposed by a lug forming cable clamp collar. Moreover, each sleeve is a machined part and each stub section is either a one-piece machined part or a machined part with attached parts.

particularly welded.

  This known device has in particular the following important disadvantages: 1) There is a risk of rupture of the continuity of electrical conduction especially at the junctions between each coupling sleeve and the adjacent stake sections during the driving operation of the stake in particular by threshing as well as possibly at the connecting lug

cable.

  2) The connection sleeve assembly imposes close manufacturing tolerances requiring a

precise and neat machining.

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  3) Since the electrical conduction is carried out exclusively by the earth rod, it must be protected against corrosion likely to reduce its conductivity. The known stake is made of a metal such as surface-treated steel, in particular by galvanizing, zinc-plating, sherardization, copper-plating or external chromisation, and a protective coating such as thin copper-plating presents a risk of tearing off the copper layer during of

the depression of the stake.

  4) The known stake is therefore of a manufacturing

complex and expensive.

  The main purpose of the invention is to eliminate the aforementioned drawbacks of the prior art by creating a method of grounding of the kind mentioned above and characterized in that it consists in using, as an electrode buried in the ground, an extreme section. bare or stripped of the conductor cable itself. According to another characteristic of the invention, the end of the above-mentioned conductive cable is pushed directly into the ground to a sufficient depth corresponding to the length of the bare or stripped bare end section, by driving a penetration means attached to said end of the cable to drive

this one deep in search.

  For the solution of the aforementioned technical problem, the invention creates a grounding device for the execution of the aforementioned method and of the aforementioned type with a stake connected to a conducting cable, this device being characterized in that the terminal portion of said cable is bare or stripped and its end is fixed to the lower end of said stake, especially in the vicinity, in particular immediate or near its penetration point, so that

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  said terminal portion of said cable extends along said stake preferably over the entire buried length thereof and is in direct continuous contact with the surrounding ground over the entire length thus buried of said terminal portion of cable. Unlike the state of the prior art, the post according to the invention therefore no longer fulfills the function of an electrode and serves only to drive the conductive grounding cable, in particular copper in the earth up to the ground. at a suitable chosen or predetermined depth. The electrical conductive connection is thus perfect because there is no more cable connection lug and it is in direct contact in direct continuous manner over its entire length buried with the surrounding earth. In addition, since the post plays only a simple role of coach member, it no longer requires special protection or appropriate special means of assembly to ensure good continuity of the

electrical conduction.

  According to another characteristic of the device according to the invention, the aforementioned cable is housed, at least partially in the transverse direction, in a longitudinal recess of the post extending in a manner

continue along this one.

  According to yet another characteristic of the invention, the above-mentioned post consists of two elements, respectively relatively long and relatively short lower, said lower element ending downwards by the penetration point and comprising, at the end of its upper end, an axial recess forming a socket into which the lower end of said upper element is assembled to assemble it to the lower element in aligned alignment thereof, the aforementioned cable being

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  previously fixed by its end to the lower end of said upper element, so as to penetrate

  in said socket in assembled position.

  It is advantageous to use a profiled post of the aforementioned type and, according to yet another characteristic of the invention, the profiled part of said stake is constituted by the aforesaid upper element drilled, at its lower end, a hole through a rib or the common bottom of two diametrically opposed grooves, the end of the cable.a threaded into this hole and folded in a loop, so that said cable and its folded branch are housed respectively in two adjacent or opposite grooves, the aforementioned sleeve having a cavity with a uniform cross-section of the prism circumscribing said upper element for sliding fit of the latter in said socket, said folded cable loop being preferably engaged by clamping or by force

in said socket.

  According to yet another characteristic of the invention, the aforementioned bush has a substantially prismatic cavity of uniform polygonal section or

  cylindrical circular at least in the separated state.

  The profiled post is preferably of cruciform cross-section and, according to yet another characteristic of the invention, the above-mentioned upper element is constituted by a profiled bar, in particular rolled or drawn, terminating at each end with a substantially flat transverse face and perpendicular to the longitudinal axis of the bar. According to yet another characteristic of the invention, the abovementioned lower element consists of a section of tube that is cylindrical with a circular cross section or a prismatic section with a square cross-section, forming the aforementioned bush and a short section of profiled profiled bar. to one

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  end of converging and converging inclined cutting edges and partially fitted at its opposite end into said tube section so as to protrude beyond

  it and preferably welded thereto.

  This design of the stake according to the invention offers considerable economic benefits through the reduction of costs due to a significant simplification of the structure and therefore the manufacturing since the post consists essentially of products such as tubes and bars available commercially and requiring virtually no machining other than cutting the bars and tubes, drilling the cable hole in the bar and cutting the tip

of a bar end.

  The invention will be better understood and other purposes, features, details and advantages thereof will become more clearly apparent on reading the

  explanatory description which will follow by referring to

  attached schematic drawings given solely by way of non-limiting examples illustrating various currently preferred specific embodiments of the invention and in which: FIG. 1 is a shortened overall view in elevation and in partial vertical section along the line; of section II of FIG. 3, of a preferred embodiment of the grounding device according to the invention in a completely assembled configuration and in buried service position and with a threshing bolt, forming a driving cap, placed coaxially above and away from the post, the device being seen in the direction of a longitudinal plane bisecting symmetry of the stake;

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  FIG. 2 is an isolated fragmentary external view of the lower end forming a point of penetration of the peg, seen in the direction of the diagonal longitudinal plane of symmetry of the pitch peg by two opposite fins; - Figure 3 is a cross-sectional view along the section line III-III of Figure 1; FIG. 4 is an isolated external view of the connecting sleeve in a relative angular position shifted by 900 around its central longitudinal axis with respect to its representation in FIG. 1; - Figure 5 is a cross-sectional view along the line V-V of Figure 1; FIG. 6 represents a fragmentary view, similar to FIG. 1, in elevation and in partial vertical section along the section line VI-VI of FIG. 7, showing the lower part of the upper element of the post and FIG. lower element thereof according to an alternative embodiment in assembled configuration; - Figure 7 is a cross-sectional view along the section line VII-VII of Figure 6; FIG. 8 is a view similar to FIG. 6, in vertical cross-section with partial cutaway, showing another embodiment of the lower stake element with two alternative embodiments of the lower extreme point thereof, respectively according to the half left and right views; and FIG. 9 is an isolated view, in median longitudinal section, of a connecting sleeve conforming to FIG.

another embodiment.

  According to the embodiment shown in Figures 1 to 5, the grounding device, generally designated by the reference numeral 1, consists essentially of a post 2 recessed

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  completely or almost entirely in the soil whose surface is designated by the mark 3 and an electrically conductive cable 4 mounted on the stake and out of the ground to be connected to the electrical system to be protected (not shown). The stake is advantageously formed, over most of its length, by a profiled bar cruciform cross section substantially uniform and symmetrical with respect to its central longitudinal axis. The four branches of this cruciform profile are uniformly angularly spaced, thus defining, along the bar, four radially protruding ribs or fins and substantially flat or flat, diametrically bumped in two-to-two alignment along two orthogonally intersecting planes, thus delimiting, between them, respectively four grooves substantially in the form of dihedral right as is clearly visible on

Figures 2 and 3.

  Stake 2 consists essentially of at least two parts, namely: a lower element 5 and an upper element 6 that can be assembled to the lower element 5. The lower element 5 consists of a profiled bar section with a cross section cruciform 5a terminating at its lower end by a blunt portion forming a penetration point into the ground and a bushing 5b advantageously constituted by a section of tube of substantially square cross section, which is nested. partially on the upper end of the bar section 5a and fixed thereto for example by welding. The embossing depth is preferably substantially less than half the length of the sleeve, for example representing about a quarter of the length of the sleeve, the fitting of the rod portion in the sleeve being advantageously effected according to a sliding fit.

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  and the upper end of the bar section 5a having a substantially flat terminal transverse end face. The bar section 5a and the sleeve b are for example substantially the same length. The lower extreme end of the bar section 5a is produced by cutting off each end of fin or rib obliquely, so that the cutaway of each groove or fin has a rectilinear edge inclined for example at an angle of about 30.degree. on the central longitudinal axis of the bar section. Each diagonal or transverse width of the bar is for example 30 mm and the thickness of each fin or rib is for example

3 mm.

  The upper element 6 of the stake consists of at least one profiled cross section section with cruciform straight cross section, preferably substantially identical, by its shape and dimensions in cross section to the lower section of bar 5a. According to the embodiment shown in FIG. 1, the post 2 is advantageously of length selectively variable.

  in a discontinuous manner by unitary quantities

  predetermined, so as to be extensible at will according to the existing local requirements and in particular according to the nature of the ground in depth. For this purpose, the upper element consists of several profiled section sections of cruciform straight cross-section, for example two such sections in FIG. 1, comprising a main or base lower section 6a and at least one upper section of the same type. 6b forming extension and assembled to the base section 6a in extension coaxially aligned therewith making

  thus the rod extensible at will.

  The upper element 6 and, in particular, the base section 6a thereof is connected quickly and easily to the lower element 5 by assembly.

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  directly to the latter, only by simply fitting, preferably with a sliding fit, the lower end of the upper member 6 into the sleeve 5b by penetrating into it over the remaining free depth (corresponding for example approximately to quarter of the length) of the latter until it comes into abutment against the upper end of the lower bar section, fitted in the lower end portion of the sleeve 5b. The upper element 6 or its base section 6a thus comes directly into simple abutment on the lower blunt bar section 5a substantially along the transverse joint plane represented by its trace 7 in FIG. 1. Each of the sections constituting the element 6, has, at each of its opposite ends, a terminal transverse face

  substantially flat at the end of the end.

  The various bar sections, such as 6a, 6b, are successively connected to one another by coaxial extension substantially aligned by means of rapid assembly of the two adjacent or adjacent end portions of each pair of successive sections. Each such rapid assembly means is advantageously constituted by a coupling sleeve 8 preferably formed by a tube section, for example of substantially the same length as the sleeve 5b. According to the example shown in FIGS. 1 and 4, the tubular sleeve 8 is advantageously substantially identical to the sleeve 5b and consists of a substantially square cross-section of tube of square section, for example of 28 mm side and 2.6 mm wall thickness. The two adjacent extreme portions of two successive bar sections, such as 6a, 6b, of the upper element 6 of the stake are respectively inserted, by simply sliding fit preferably sliding fit in a tubular sleeve 8 such a depth penetration

  preferably not exceeding the half-length of the sleeve.

  To prevent each sleeve 8, in its mounted assembly position, to move unexpectedly by sliding along the upper element 6 and in particular to descend by gravity along it in a vertical position, the internal cavity of the sleeve comprises a stopper 9 extending transversely protruding into this cavity and located substantially in the middle of the sleeve. This stopper 9 is advantageously constituted by a simple transverse axis, forming peg, pin, pin or the like, located in the common median longitudinal plane of two opposite parallel side walls of this prismatic tubular sleeve. To report or fix this axis 9 in this prismatic sleeve, the axis is advantageously of a length slightly greater than the transverse width of the sleeve measured parallel to a side wall thereof and is inserted through two aligned holes respectively drilled through two opposite parallel side walls of the sleeve in a direction substantially perpendicular to its longitudinal central axis. Thus, the axis 9 protrudes, in its mounted position, slightly on each opposite side of the sleeve and, to fix the axis to the latter, it suffices for example to weld at least one end protruding from this axis externally on the side wall. corresponding to the sleeve as can be seen in FIG. 4. The axis 9 is advantageously of round cylindrical shape and the

  sleeve 8 and the axis 9 are preferably made of steel.

  To allow the convenient passage of the conductor cable 4, it is important that the maximum transverse dimension and in particular the diameter of the axis 9 is not greater than the diameter of the circle entirely inscribed in the solid surface portion of the right cross section of the

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  profiled bar being tangent to the respective bottoms of the dihedral grooves defined by the cruciform configuration of this cross section. In other words, the diameter of the axis 9 should not exceed the thickness of the solid core forming the inner core of the profiled bar, measured in a longitudinal bisecting plane of symmetry of said bar, passing through the central longitudinal axis thereof. this. With the aforementioned dimensions of the profiled bar cross section, indicated previously by way of example, the axis 9 will for example have a diameter of 6 mm. In the assembled mounting position, the sleeve 8 will thus rest by its transverse axis 9 on the end face of the upper end of the profiled bar section 6a fitted into the lower part of said sleeve and the profiled profile bar section 6b, fitted by its lower end part in the upper part of the sleeve 8, will thus rest on the transverse axis 9 of the latter as is visible on

Figure 1.

  For mounting and fixing the conductive cable 4 on the device 1, the upper element 6 or its base section 6a is pierced, in its portion

  lower extremity fitting into the socket 5b and by.

  for example substantially at half-depth of penetration into this sleeve, a transverse hole 10 whose axis is located substantially in a longitudinal plane bisecting symmetry of the profiled bar thus passing through the inner core thereof, that is, that is, the common bottom of two opposite dihedral grooves (see Figures 1 and 3). The diameter of this hole substantially corresponding to the diameter of the conductive cable 4 and this conductive cable is threaded, by its lower end portion of a length preferably greater than the depth of penetration of the element 6 into the sleeve 5b, through which hole 10 and folded upwardly loop so that the folded branch of this loop has a length at least equal and preferably greater than said half-depth of penetration. The folded short branch 4a of the aforementioned loop and the long branch 4b thereof forming the main part of the cable 4 are thus respectively housed along their entire length in two opposite grooves of the profiled bar 6, the long branch 4b extending on at least most of

the upper element 6.

  The mounting and the establishment, in the active operating position, of the device 1 then take place as follows: the various parts 5, 6a, 6b and 8 of the post 2 as well as the stripped cable 4 on its portions 4 a , 4b but electrically isolated on its remaining portion 4c having been prefabricated and made available, the lower end portion of the cable 4 is threaded through the hole provided in the lower end portion of the upper element 6 or the base section 6a by folding the loop cable according to the two branches respectively short 4a and 4b long which is respectively housed in two opposite longitudinal grooves of the base section 6a. Then the base section 6a, thus provided with the cable loop, is connected to the upper free cavity of the bushing 5b, the fins of the profiled bar being oriented diagonally with respect to the square prismatic shape of this bushing. The portion of the cable 4, which is intended to be located in the ground, must be bare or stripped and this cable is advantageously made of copper with a diameter for example of 8 mm and a surface area of cross-section for example mm. The fit of the profiled bar 6a in the bushing 5b is possibly carried out by force because of the thickness of the cable which will then be somewhat flattened in its part located inside the bushing 5b, so that the element 6 remains assembled to the sleeve 5b in particular by frictional clamping of the side walls of the sleeve against the cable located inside thereof. To further increase the strength of this attachment and in particular the resistance of this assembly to the longitudinal tension, the sleeve 5b will advantageously be crimped on the profiled upper section element 6 by permanent local deformation of at least the parts of the upper edge. of the socket which are in contact with the two branches of the folded cable loop, so as to grip them as shown in Figure 3 on which we see that the two opposite side walls of the sleeve 5b, which are in contact with the cable 4, are locally deformed by convexly bulging outwards at the locations

  respective branches of the cable loop.

  To drive the vertically disposed rod thus formed into the earth 3, the upper end of the base section 6a of the profile bar 6 is capped with a detachable clevis 11 constituted by a sleeve-shaped thimble bush at the upper end of FIG. 1, this rivet being advantageously of generally circular cylindrical configuration having a length or height of, for example, 55 mm, an outside diameter of 40 mm and an inside diameter of, for example, 31 mm with a cavity depth. internal for example 40 mm, these dimensions being adapted for easy sliding assembly to those of the profiled bar previously given as an example. The post is then driven into the ground by striking the knuckle 11 with an appropriate hammer. By sinking into the ground, the stake carries with it, the conductor cable 4 into the ground as it penetrates into it. When the shaped bar section 6a no longer protrudes above the ground 3 by a length slightly greater than the length of the coupling sleeve 8, the latter, after previous removal of the rivet 11 and threading of the branch 4b cable through the sleeve is fitted on the emergent upper end of the section 6a until the stop pin 9 abuts against the end face at the end of this section. The sleeve 8 must have a relative angular position about its longitudinal axis that the stop axis 9 is oriented perpendicular to the

  plane of the cable loop (see Figures 1 and 5).

  Then, the section profiled bar following 6b, forming pole extension, is pushed fully into the upper free part of the sleeve 8 until this section 6b comes into abutment, by its lower end face, against the axis 9 of the sleeve. The upper end of the extension 6b is then capped removably from the - threshing ram 11 and then continues the depression of the post in the ground by shocks or percussion applied to the rivet. The usefulness of this rivet is in particular to avoid a matting of the upper end of the stake under the action of driving shocks applied thereto. After sufficient depression of the rod thus extended, it can, if necessary, further increase the length of the stake thus adding successively one or more extensions similar to the extension 6b by repeating the previously described operations. The upper end of the last extension may or may not exceed somewhat of the ground. It is thus possible to provide, for example, two different lengths of post 2, for example 1 m and 1.5 m, respectively, by providing a post-top body element 6, e.g. 0.9 m and 1.4 m long, and composed of a base section 6a and one or two extensions each identical to the section 6b, the element 6 being assembled by means of two coupling sleeves such as 8 interposed respectively between

the three sections.

  With this improved arrangement, the bare buried part of the cable 4, located between the surface of the ground 3 and the upper end edge of the sleeve 5b and along the post 2 being housed therein, is in continuous direct contact, on its entire length or height, with the surrounding earth thus realizing a continuous electrical connection of great length so large surface contact with the earth. As the burying part of the cable 4 is housed substantially entirely in a corresponding longitudinal recess of the upper element 6 of the stake 2, this portion of the cable is relatively protected during its driving into the ground by the post during the operation. depressing it. The upper part 4c of the cable 4, located at

  the outside of the floor 3 and suitably insulated

  is connected to the electrical installation at

protect.

  FIG. 6 shows a partial modification of the structure of post 2 in that the prismatic tubular sleeve with square cross-section, forming sleeve 5b and / or coupling sleeve 8, is replaced by a cylindrical sleeve with circular cross-section . In the case of such a cylindrical sleeve 5c, the axis 9 is arranged diametrically. Figures 6 and 7 show the crimping of the upper part of the cylindrical sleeve 5c on the upper element 6 and the cable 4 by local deformation of two wall portions

  diametrically opposite sides of this sleeve 5c.

  FIG. 8 represents a different embodiment of the lower element 5 of the post 2. This lower element is constituted by a machined hollow part 5 'of substantially cylindrical conical shape comprising a cylindrical bored body 12 forming the aforesaid bush which advantageously comprises an upper end portion 12a thinned by reducing the outer diameter and ending at the opposite end with a conical tip 13. This conical tip 13 may be integral with the cylindrical body 12, thus forming a single piece as this is visible on the lower half-view of the left of Figure 8 or be reported by welding as can be seen on the lower right half-view of Figure 8. In the latter case, this tip 13 is constituted by a separate machined part preferably comprising a cylindrical tip shouldered small diameter coming into the end end corre The thinned upper portion 12a of the cylindrical body 12 allows a convenient crimping thereof on the upper element 6 and the cable 4 by local deformation of two diametrically opposite side wall portions of said body respectively opposite of the two aforementioned branches 4a and 4b of the cable loop. FIG. 9 illustrates another embodiment of the coupling sleeve 8 which is constituted by a machined hollow cylindrical part 8 'comprising two identical bores 14a, 14b symmetrical with respect to the median transverse plane and separated by an internal annular shoulder 15 forming the abutment stop above. This piece has for example an outside diameter of 40 mm, a bore diameter for example of 30 mm, the free section of passage, at the right of the shoulder, having

for example a diameter of 20 mm.

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  In the case of FIG. 8, the apex angle of the conical tip 13 is preferably about 60 and, in the mechanically welded variant, the cylindrical body

  12 is advantageously constituted by a tube.

  It should be noted that the independent industrial product, consisting of post 2 and characterized by its shape, constitution and structure, is part of

  integral of the present invention.

Claims (14)

R E V E N D I C A T IO N S   A method of grounding an electrical installation by electrical connection thereof by means of a conductive connection cable (4) with an electrode (2) of adequate length, preferably substantially vertical, embedded in the sol (3) and in continuous direct contact with it, characterized in that it consists in using, as an electrode, an extreme bare or stripped section (4b) of said cable (4) itself.   2. Method according to claim 1, characterized by the direct depression of the end (4a) of the above-mentioned conductive cable (4) in the ground (3) to a sufficient depth corresponding to the length of the bare or bare extreme section. aforesaid (4b), by beating a penetrating means (2) attached to said end   cable (4a) to drive the latter deep underground.   Earth-quenching device (1) for carrying out the method according to claim 1 or 2, of the straight-earth metal straight-ground straight picket type (2), connected to a conductive cable (4) connected to the electrical installation to be protected, characterized in that the terminal portion (4a, 4b) of said cable (4) is bare or stripped and its end (4a) is fixed to the lower end portion of said stake (2) in particular near or in the vicinity of its penetration point (5a, 13), so that said end portion (4b) of said cable (4a) extends along said stake (2) preferably over the entire buried length thereof and is in continuous direct contact with the surrounding ground (3) over the entire length thus buried of said terminal portion of cable (4b). 261733 8   4. Device according to claim 3, with peg (2) having at least one open longitudinal recess extending from the upper end of the stake to the vicinity of its lower end (5) penetration point (5a, 13). ), characterized in that the aforesaid cable (4) is housed, at least partially in transverse direction, in said recess in   extending continuously along it.   5. Device according to claim 4, characterized in that the aforesaid stake (2) consists of two respectively relatively long (6) and relatively short lower (5, 5 ') respectively, said lower member (5, 5') ending at the bottom by the penetration tip (5a, 13) and having, at the end of its upper end, an axial recess forming a bushing (5b, 5c, 12) into which the lower end of said upper element ( 6) for assembling it to the lower element (5, 5 ') in an aligned extension thereof, the aforesaid cable (4) being previously fixed, by its end (4a), to the lower end of said element upper (6), so as to penetrate into said socket (5b, 5c, 12) in the assembled position. 6. Device according to claim 5, profiled stake (2) uniform cross-section regular uniform symmetrical shape having ribs or fins radially projecting and angularly spaced uniformly or equidistantly delimiting between them, respectively, recessed dihedral grooves, characterized in that the profiled portion of said post (2) is constituted by said upper element (6) pierced at its lower end by a hole (10) passing through a rib or the common bottom of two diametrically opposed grooves the end (4a) of the cable (4) being threaded into this hole (10) and folded in a loop, so that said cable (4b) and its folded branch (4a) are respectively housed in two adjacent or opposite grooves, the aforesaid bushing (5b, 5c, 12) having a uniformly cross-sectional cavity of the prism circumscribing said upper element (6) for ustement sliding of the latter in said socket, said folded cable loop preferably engaging clamping or force in said socket (5b, 5c, 12).   7. Device according to claim 6, characterized in that the aforesaid sleeve (5b, 5c, 12) is crimped on the aforesaid upper element (6) by permanent local deformation of at least the parts of the upper edge of said sleeve which are in contact with the two branches (4a, 4b) of the folded cable loop   (4) above, so as to enclose them.   8. Device according to claim 6 or 7, characterized in that the aforesaid sleeve (5b, 5c, 12) has a substantially prismatic cavity of uniform polygonal section or circular cylindrical at least to the separated state.   9. Device according to claim 8, profiled stake (2) cruciform cross section, characterized in that the aforesaid upper element (6) is constituted by a profiled bar including laminated or stretched ending at each end by a substantially flat transverse face   and perpendicular to the longitudinal axis of the bar.   10. Device according to claim 9, characterized in that the aforesaid lower element (5) consists of a tube section is cylindrical circular cross section or prismatic square cross section forming the aforesaid sleeve (5b, 5c) and a short section of profiled bar (5a) blunted to 26 7338   one end following inclined cut sides.   convergent and concurrent and partially fitted, at its opposite end, in said tube section (5b, c) so as to protrude from it and preferably welded thereto. 11. Device according to claim 9, characterized in that the aforementioned lower element is constituted by a machined hollow revolution piece (5 ') of substantially cylindro-conical shape comprising a bored cylindrical body (12) forming the aforesaid sleeve to upper end portion (12a) tapering by reducing the outer diameter and terminating at the opposite end by a conical tip (13) integral with said body (12) or reported by welding on this one.   12. Device according to one of claims 9   to 11, selectively extensible peg (2), composed of several sections (6a, 6b) which can be assembled end to end to each other by intermediate coupling sleeves (8, 8 '), each of which is nestable, by its opposite ends, respectively on the two adjacent ends of two successive sections (6a, 6b), characterized in that the aforesaid upper element (6) constitutes the extensible portion of said post (2) and each section (6a, 6b) is constituted by said profiled bar while each sleeve is constituted either by a tube end or prismatic square cross section (8) or cylindrical circular cross section, preferably traversed in the middle by a pin (9) welded externally by at least an end protruding on said tube end (8), or by a machined hollow cylindrical part (8 ') having two identical bores (14a, 14b) symmetrical with respect to the tra nsversal median and   separated by an inner annular shoulder (15).   13. Device according to one of claims 9   at 12, characterized by a substantially cylindrical thimble (11) intended to cap removably   the upper end of the aforementioned stake (2).   14. Industrial product forming a ground stake (2), characterized in that it has the form, constitution and structure set forth in one of the Claims 9 to 12.