WO2002054553A2

WO2002054553A2 - Cable installations and components therefor

Info

Publication number: WO2002054553A2
Application number: PCT/ZA2001/000204
Authority: WO
Inventors: Barry Howard; Trevor Harrison Thompson
Original assignee: Barry Howard; Trevor Harrison Thompson
Priority date: 2001-01-02
Filing date: 2001-12-14
Publication date: 2002-07-11
Also published as: AU2002227453A1; WO2002054553A3

Abstract

A cable installation is provided in which at least one elongated cable (3) is located in a composite tubular protective cover (4) that is split longitudinally so as to enable the cable to be introduced transversely into a part (6, 10) of the cover prior to another part (6, 10) of the cover being installed to cooperate therewith and to form said composite tubular cover. The tubular cover parts have cooperating locating formations (7, 8, 12) extending along the length thereof so as to locate one part of the cover relative to the other. The cable installation is particularly appropriate to underground cables and preferably has short removable sections (20) to provide access openings at spaced intervals along the length of the composite cover.

Description

CABLE INSTALLATIONS AND COMPONENTS THEREFOR

FIELD OF THE INVENTION

This invention relates to cable installations whereby services such as the supply of electricity and communications facilities such as underground cable installations or above ground cable installations in industrial and commercial buildings in which the cable needs at least some protection or some support, or both. The invention also relates to components of such an installation.

BACKGROUND TO THE INVENTION

In the installation of underground cables such as those providing services to the public and industry, it is usually accepted that the cables require some form of protection against damage that may be occasioned by excavations being made.

One way in which some form of protection is presently afforded underground cables is for the cables to be laid in a trench; covered with a layer of sifted soil or sand to prevent direct contact of large stones or other sharp objects with the cable surface; and for a layer of protective cable tiles to be laid on the top of that layer prior to the trench being filled with unsifted soil, generally that was excavated from the trench. This procedure is costly and in no way contributes to facilitating the maintenance, replacement or addition of one or more cables passing through the trench.

Another way in which cables may be protected is to thread them through a prefabricated sleeve that is then buried in a trench, in this case, possibly without the layer of sifted soil or sand. The threading of the cables through the tubular sleeve is difficult, slow, and therefore generally costly. In the case of above ground cables within commercial and industrial buildings, these are very often secured to cable trays in order to support them and are otherwise exposed. This may not be desirable as they are directly available, for example, to animals, to gnaw at the insulation and possibly expose and even rupture conductors of the cables.

OBJECT OF THE INVENTION

It is, accordingly, an objective of this invention to provide a cable installation in which the drawbacks identified above may be diminished, at least to some extent.

SUMMARY OF THE INVENTION

In accordance with one aspect of this invention there is provided a cable installation in which at least one elongated cable is located in a composite tubular cover wherein the tubular cover is split longitudinally so as to enable the cable to be introduced transversely into a part of the cover prior to another part of the cover being installed to cooperate therewith and to form said composite tubular cover.

Further features of the invention provide for the tubular cover parts to have cooperating locating formations extending along the length thereof so as to locate one part of the cover relative to the other, such locating formations optionally being provided by an auxiliary separately formed joining strip; for the tubular cover to be held in its tubular configuration by means of a series of fastening devices, generally encircling the outside of the cover and typically being cable ties, extending circumferentially around the outside of the closed tubular cover; for the cover assembly to include junction fittings such as may be necessary to form a bend, a tee-junction, or a butt junction and each of which is split along lines parallel to the axial direction of the fitting; and for the fittings to have, at the openings thereto, an internal diameter approximately the same as the external diameter of the free end of the cover to be received therein. As an alternative to a butt junction fitting each elongated length of cover may be formed at one end into a socket having an internal diameter chosen to receive the external diameter of the opposite end and such sockets can be formed using a heated mandrel to expand a short length of a cut end of an extruded cover part.

Still further features of this aspect of the invention provide for the tubular cover to be of circular shape in cross-section composed of two parts of substantially semicircular shape in cross-section that are preferably made as a single piece with the two parts hinged together along one longitudinal edge by means of an integral hinge, or the two parts may be separate and adapted to be joined by locating formations extending along both edges of the semicircular parts; for sealing means to be provided for sealing the parts of the tubular cover and junction fittings together to form a sealed enclosure for the cable or cables therein; for elongated parts of the cover to be made of extruded plastics material whilst junction fittings will preferably be injection moulded from a contact double plastics material, if not the same; for short sections of one part, generally an operatively uppermost part, to be provided along the length of a composite cover at spaced intervals to provide openings of a suitable length to facilitate inspection, service or replacement of existing cables or to facilitate the introduction of additional cables with the rest of the cover closed, in buried, and in situ.

In the accordance with a second aspect of the invention there is provided a method of protecting one or more cables comprising the steps of locating one part of a cover assembly as used in an installation defined above with the cable or cables positioned within the said part of the cover; installing the other part of the cover in cooperating relationship therewith to form a tubular cover assembly; and fastening the two parts together. The invention also provides a method of installing underground cables comprising the steps of excavating a trench, laying one or more cables in the trench and positioning same in an open elongate part of a cover as defined above within the trench, installing a cooperating part of a cover to totally enclose the cable or cables, securing the two parts of the cover together, and burying the cover with the cable or cables inside it.

A further feature of the method of this invention provides for one or more draw cables to the installed together with the cable or cables so that additional cables can be drawn through the cover longitudinally utilizing a draw cable.

The invention still further provides components of a composite cover assembly, in particular elongate cover parts and split fittings particularly adapted for use in an installation defined above.

In order that the invention may be more fully understood the application thereof to underground cables will be further described with reference to the accompanying drawings. Whilst the following description is aimed at underground cables, it is within the scope of this invention that the covers of the invention may equally well be used in above-ground installations such as in commercial and industrial premises and then, optionally in place of cable trays or the like as may be appropriate.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings: -

Figure 1 is a schematic cross-section taken through an underground cable installation according to the invention; Figures 2 and 3 are each a cross-section taken through two different configurations of cover assembly according to the invention;

Figure 4 illustrates schematically a number of collinear lengths of cover assembly installed relative to each other;

Figure 5 illustrates one half of a bend for use in an installation according to the invention;

Figure 6 illustrates one half of a tee junction for use in an installation according to the invention;

Figure 7 is a sectional elevation illustrating one form of butt joint between the two collinear lengths of cover according to the invention;

Figure 8 is an elevation showing the external view of the joint of the type illustrated in Figure 7 and also illustrating the fastening means employed;

Figure 9 is a sectional elevation similar to Figure 7 but showing a butt joint in which one end of each elongate length of composite cover is formed into a socket; and,

Figure 10 is a diagramatic elevation showing a short removable section of the upper part of an installed cover that is removable for maintenance and upgrading purposes. DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Referring firstly to Figure 1 of the drawings, there is illustrated diagramrnatically a trench (1 ) excavated out of a body of soil (2) and in the bottom of which is laid a series of cables (3) with the various cables being enclosed in four different covers (4) according to the invention. The covers are simply covered with ordinary unsieved soil (5) that is compacted adequately and the soil can simply be that originally removed to form the trench. No cable tiles are necessary, and no sieved soil or sand is required.

Referring now more generally to Figures 2, each cover may be made as two elongate cover parts (6) each of semicircular shape in cross-section and each of which is made as a plastics extrusion, conveniently from polypropylene or other suitable material. In the case of the variation illustrated in Figure 2, the one edge of each length of extrusion has a tongue

(7) extending along the length thereof and directed, in cross-section, in a generally circumferential direction, and a cooperating complementary groove

(8) formed along the other longitudinal edge of the cover part. In this case the one part is laid on the bottom of the trench and the cable is positioned in it following which the other part is attached to the first part by introducing the tongue (7) into the cooperating groove (8) along each edge. The closed cover is fastened in this position using cable ties (9) encircling the cover on the outside thereof as shown in Figure 8.

In the variation illustrated in Figure 3 and that is presently preferred, the two parts (10) of the cover are made integral as one piece with the two parts being interconnected by an integral hinge (11). The opposite edges (12) are shown as being attached together using a separate joining strip (13) in the form of a plastics extrusion. The joining strip (13) has, in cross-section, two oppositely directed grooves (14) that receive the free edges of the cover. The cover is fastened in its closed positions using fasteners such as cable ties as indicated above, or closed by the interconnecting tongue and groove configuration (7, 8).

Clearly the parts of the cover assembly are produced in predetermined lengths and, at installation, the various lengths indicated by numeral (4) in Figure 4 are joined by means of butt joints that can assume either of two different basic forms.

The one form is shown in Figures 7 and 8 and in this form a split tubular fitting (15) has an inside diameter approximately the same as the outside diameter of the composite cover (4) and the tubular fitting is also held in the closed position by means of cable ties (16) encircling the fitting.

The butt joint illustrated in Figure 9, on the other hand, does not involve any additional fitting and relies on a slightly enlarged end (17) to the cover (4) that in effect forms a socket so that the plain end of one length of composite cover is received in the socket formed at the complimentary end of the adjacent length of cover. Such a socket can easily be formed utilizing a heated mandrel on a length of cover that has just emerged from an extrusion die, for example.

In a manner similar to the fitting described with reference to Figures 7 and 8, other fittings such as a corner fitting (18) as illustrated in Figure 5 and a tee junction fitting (19) and as illustrated in Figure 6 can be similarly installed together with elongated cover parts to form a composite cover assembly passing through bends and having junctions.

Finally, referring to Figure 10, it is preferred that the operatively upper part (4a) have short sections (20) that are removable independently of the balance of the corresponding upper parts of the cover so that access to the interior of the cover can be provided at spaced intervals along the length of the composite cover assembly. Such access sections (20) can be provided at any required spacing along the length of the cover to provide for maintenance, removal of cable sections, and replacement of cable sections, or the installation of new cables within the existing cover. In order to replace or install new cables it would therefore only be necessary to dig a hole at the location where the access sections are provided and the new cable or repaired cable can be drawn through the existing cover by way of such access sections without disturbing or unearthing the balance of the length of the covers and enclosed cables.

It will be understood that numerous variations may be made to the embodiment of the invention described above without departing from the scope hereof. In particular, the cross-sectional shape of the cover can be varied widely as may be required although it is generally considered that a circular cross-section will be most appropriate from a strength point of view. Also, the locating formations carried by the cover parts can be varied widely as can the means for securing the two parts together. Indeed, it is within the scope of this invention that, for example in the case of a tongue and groove joint, the tongue and/or groove could be provided with saw tooth locking or other clipping formations so that the two cover parts become locked together automatically. Such an arrangement may not, of course, be suitable for the removable access sections. Still further, the materials of construction of the cover could be varied as may be required the invention not being restricted in any way to plastics materials.

Claims

CLAIMS:

1. A cable installation in which at least one elongated cable (3) is located in a composite tubular cover (4) wherein the tubular cover is split longitudinally so as to enable the cable to be introduced transversely into a part (6, 10) of the cover prior to another part (6, 10) of the cover being installed to cooperate therewith and to form said composite tubular cover.

2. A cable installation as claimed in claim 1 in which the tubular cover parts (6) have cooperating locating formations (7, 8) extending along the length thereof so as to locate one part of the cover relative to the other.

3. A cable installation as claimed in claim 2 in which the locating formations (12) are provided by an auxiliary separately formed joining strip (13).

4. A cable installation as claimed in any one of the preceding claims in which the tubular cover is held in its tubular configuration by means of a series of fastening devices (9, 16) encircling the outside of the cover.

5. A cable installation as claimed in any one of the preceding claims in which the cover assembly includes junction fittings such as may be necessary to form a bend (18), a tee-junction (19), or a butt junction (15) and each of which is split along lines parallel to the axial direction of the fitting.

6. A cable installation as claimed in claim 5 in which the fittings have, at the openings thereto, an internal diameter approximately the same as the external diameter of the free end of the cover to be received therein.

7. A cable installation as claimed in any one of the preceding claims in which a butt junction is formed by providing each elongate length of cover with a socket (17) having an internal diameter chosen to receive the external diameter of the opposite end.

8. A cable installation as claimed in any one of the preceding claims in which the tubular cover is of circular shape in cross-section and is composed of two parts (10) of substantially semicircular shape in cross- section that are made as a single piece with the two parts hinged together along one longitudinal edge by means of an integral hinge (11).

9. A cable installation as claimed in any one of claims 1 to 7 in which the tubular cover is of circular shape in cross-section and is composed of two separate parts (6) of substantially semicircular shape in cross- section that are adapted to be joined by locating formations extending along both edges of the semicircular parts.

10. A cable installation as claimed in any one of the preceding claims in which short removable sections (20) of one cover part, generally an operatively uppermost part, are provided along the length of a composite cover at spaced intervals to provide access openings of a suitable length to facilitate inspection, service or replacement of existing cables or to facilitate the introduction of additional cables with the rest of the cover closed, in buried, and in situ.

11. A method of protecting one or more cables comprising the steps of locating one part of a cover assembly as used in an installation claimed in any one of claims 1 to 10 with a cable or cables positioned within the said part of the cover; installing the other part of the cover in cooperating relationship therewith to form a tubular cover assembly; and fastening the two parts together as may be required.

12. A method of installing underground cables comprising the steps of excavating a trench (1 ), laying one or more cables in the trench and positioning same in an open elongate part of a cover as claimed in any one of claims 1 to 9 within the trench, installing a cooperating part of a cover to totally enclose the cable or cables, securing the two parts of the cover together, and burying the cover with the cable or cables inside it.

13. Components of a composite cover assembly forming part of an installation as claimed in any one of claims 1 to 9.