PROTECTIVE HOUSING FOR A CABLE SPLICE CLOSURE

Abstract: A kit of parts for protectively enclosing an exposed splice between two or more cables that are carried in ducts, comprising: a) an inner cover for enclosing the exposed cable splice; b) a removable protective outer housing for completely enclosing the inner cover, the housing having at least one open or openable end to receive an end region of a duct carrying a spliced cable; and c) an end block for blocking the end of the housing around the end region of the cable duct.

Description: PROTECTIVE HOUSING FOR A CABLE SPLICE CLOSURE The present invention relates to cables, e.g. telecommunications cables (copper or optical fibre) and electrical cables. In particular, the invention relates to such cables carried in cable ducts. In some telecommunications or electrical power networks, the cables are carried in ducts in order to protect them from damage. In such networks, when two or more cables need to be spliced, it is necessary to expose a length of each cable from an end of its protective duct in order for the conductors (wires or optical fibres) of the cables to be accessed, spliced together and enclosed in a cable splice closure. The cable ducts are normally located underground (buried), and it is necessary to provide some mechanical protection for the exposed cables between the ends of the ducts and the cable splice closure. At present, this protection of the exposed cables between the cable ducts and the splice closure is provided in one of two ways. One method is to attach a bracket to the ducts to connect them to each other and to the splice closure. A protective plate is secured to the bracket to provide some degree of protection to the exposed cables (for example from excavation equipment). However, the degree of protection afforded is not great, and it is also necessary to provide seals between the exposed cables and the ends of the ducts carrying the cables, in order to prevent soil and the like entering the ducts. Furthermore, the splice closure must be sufficiently strong to provide all of the mechanical protection around the cable splice, and since it is buried directly in the earth it is exposed to grime and corrosion (for example of metal parts such as nuts and bolts). An alternative method which is used, is to install the splice closures in manholes or handholes, i.e. large permanent buried enclosures normally constructed from concrete, which are designed to provide a large space in the ground from which the surrounding soil is excluded. This has the disadvantage of being very expensive and providing less flexibility in the location of the cable splice. According to a first aspect of the present invention, there is provided a kit of parts for protectively enclosing an exposed splice between two or more cables that are carried in ducts, comprising: an inner cover for enclosing the exposed cable splice; a removable protective outer housing for completely enclosing the inner cover, the housing having at least one open or openable end to receive an end region of a duct carrying a spliced cable; and an end block for blocking the end of the housing around the end region of the cable duct. According to a second aspect of the invention, there is provided an assembly of parts which protectively encloses an exposed splice between two or more cables that are carried in ducts, comprising: an inner cover which encloses the exposed cable splice; a removable protective outer housing which completely encloses the inner cover, the housing having an open end in which is received an end region of a duct carrying a spliced cable; and an end block which blocks the end of the housing around the end region of the cable duct. A third aspect of the invention provides a method of protectively enclosing an exposed splice between two or more cables that are carried in ducts, comprising: enclosing the exposed cable splice in an inner cover, and completely enclosing the inner cover in a removable protective outer housing such that an end region of a duct carrying a spliced cable is received in an open end of the housing, and the end of the housing around the end region of the cable duct is blocked by an end block. The invention has the advantage that it provides a much higher degree of mechanical protection for the exposed region of the cables between the ends of the ducts and the inner cover which encloses the cable splice than does the bracket-and-plate system used currently, since the protective outer housing of the invention completely encloses this region. It also has the advantage of isolating the cable splice closure (i.e. the inner cover) from the surrounding soil, and therefore prevents contamination and corrosion of the splice closure (or at least any exposed metal parts of the closure). The invention also has the advantage over the use of manholes or handholes in being a much less expensive and more versatile solution. Furthermore, the invention has an advantage over a possible alternative solution which may be postulated, namely installing the splice closure itself around the ends of the cable ducts (i.e. allowing the cable ducts to extend into the splice closure rather than ending the ducts outside the closure and allowing only the cables to extend into the closure). This possible alternative solution has the problem that in order to ensure the integrity of the environmental seal of the splice closure (i.e. the protection to the cable splice against moisture and other potentially harmful contamination) it is vital to provide a watertight seal between each cable duct and the cable(s) which it carries. This would normally be extremely difficult to achieve because there is usually a large difference between the internal diameter of the duct and the external diameter of the cable. The inner cover used in the invention preferably includes a seal which seals directly around the cables. The inner cover may be formed from recoverable (e.g. shrinkable) material, e.g. elastomeric material or heat-recoverable material. The seal may comprise adhesive, e.g. heat-activatable adhesive, for example hot melt adhesive. Preferably, the inner cover is substantially rigid, e.g. formed from a non-recoverable plastics material (e.g. such as polyethylene or polypropylene). Such an inner cover preferably includes one or more seals formed at least in part from a sealing material, e.g. gel sealant or mastic etc. The inner cover may be a cable splice closure as disclosed in WO 96/09670, WO 97/27655, or WO 97/45904, the entire disclosures of which are incorporated herein by reference. Preferably, the or each end block and preferably also the end regions of the cable ducts, are spaced apart from the inner cover in use. This does not, however, preclude the possibility of the or each end block being connected, e.g. rigidly connected, to the inner cover in use, and in fact such an arrangement is preferred. Advantageously, substantially the entire protective outer housing may be substantially rigid. However, in alternative embodiments the protective outer housing may comprise a substantially rigid basic structure, such as a framework, and the portions of the cover between the rigid structure or framework may be non-rigid. Such alternative embodiments are presently less preferred however. Conveniently, the protective outer housing may be moulded. Alternatively, the protective housing may be extruded (this has the advantage of normally being a less expensive manufacturing method). The housing is preferably formed from a plastics material, e.g. polyethylene or polypropylene, although other materials (such as metal) may be used. The protective outer housing is preferably elongate, for example such that it is a moderately close fit along the length of the inner cover. The housing preferably has a significantly larger length than the inner cover, e.g. at least 10%, but preferably no more than 60%, longer than the inner cover. The protective outer housing may be formed as a single part. Preferably it is openable to permit side-entry of the cables, the inner cover and the duct end regions into it. More preferably it is formed as at least two parts, e.g. half-shells. The parts of the housing may be connected together in substantially any convenient way, e.g. by means of interlocking portions, an interference fit, or other closing means, such as one or more latches or straps, for example. In some particularly preferred embodiments, the protective outer housing may be assembled from a plurality of modules which may be connected together. For example, the entire length of the housing (or at least one elongate part of the housing, e.g. a half-shell) may be assembled from a plurality of shorter modules which are connected together. The modules may be interconnected by any convenient means, e.g. interlocking portions, an interference fit, or other suitable closing means. Some advantages of assembling the housing from smaller modules are firstly that the length of the housing may be chosen according to requirements by selecting the appropriate number of modules, secondly it is often easier to fabricate smaller components (especially when moulded), and thirdly the housing may be easier to install if it is assembled from modules at the same time as it is installed around the inner cover. The purpose of the end block(s) is to block the open end(s) of the protective outer housing around the cable ducts. The blocking is normally intended to exclude soil, dust or the like, but normally will not be watertight, although this is possible in some embodiments. The or each end block may be integral with the protective outer housing. Preferably, however, at least a part of the end block, and more preferably substantially the entire end block, is separate from the housing. The end block, or at least a major portion of the end block, is preferably substantially rigid. The end block may therefore provide mechanical protection. Preferably, the end block is formed from a plastics material, e.g. polyethylene or polypropylene. The or each end block may comprise a plurality of parts which are secured together around the cable duct(s) in use, e.g. by means of one or more connecting members such as screws, bolts or the like. Advantageously, the end block grips the or each cable duct end region so as to prevent relative longitudinal movement between the protective housing and the cable duct in use. The end block may, for example, include at least one separate duct gripper to grip the or each cable duct. In some preferred embodiments, the invention includes a seal between the end region of each duct and the or each cable carried by the duct, e.g. to prevent the ingress of moisture or other contaminants into the outer housing from within the duct. The invention will now be described, by way of example, with reference to the accompanying drawings, of which: Figure 1 shows part of a semi-assembled kit according to the invention; Figure 2 shows part of an alternative type of protective outer housing and end block; Figure 3 shows part of an end block detail for small sized cable ducts; Figure 4 is an exterior view of an assembly according to the invention; Figure 5 shows six views of a modular protective outer housing; and Figure 6 shows an enlarged cover with lid. Figure 1 shows an inner cover 1, comprising a rigid cable splice closure formed from a plastics material (e.g. polypropylene). A protective outer housing 2 is arranged to enclose the inner cover. The housing 2 comprises two substantially rigid half shells which can be connected together around the inner cover 1 by means of interlocking portions 3 and 4. An end block 5, comprising three separate parts 5a, 5b and 5c connected together by bolts 6 is shown installed around the end regions of four cable ducts 7. The end block 5 is rigidly connected to the end of the inner cover 1 by means of a connecting member 8. Exposed cables 9 which extend from the ends of the cable ducts extend into the interior of the inner cover, where the cable splice is contained. The inner cover 1 is sealed directly around the cables 9 by a gel sealing material (not shown). In addition, the cables are gripped in the end region of the inner cover by a wound gripping strip 10. The cable splice is an in-line splice, and so there will be a similar arrangement at the other end of the inner cover and outer housing, but this is not shown, for clarity. Figure 2 shows part of an alternative type of protective outer housing and end block arrangement. In this embodiment, part 11a of the end block is integral with the housing 12. A middle part l ib of the end block is a separate piece which may be connected to part 1 la by connecting means such as bolts. Figure 3 shows part of an end block detail for small sized cable ducts 13. The end block includes a port adapter 14 and a blocking tube 15 (formed in two separable halves 15a and 15b) for enclosing the ducts in the port adapter. This entire mini-assembly is for insertion into one of the cable duct ports 16 of the end block. Figure 4 is an exterior view of an assembly according to the invention. Cable ducts 7 are shown extending into a closed protective outer housing 2 through end blocks 5. Figure 5 shows six views of a modular protective outer housing according to the invention. Figures 5a and 5b are two views of a single module 17 of a half-shell 20 of the housing. In fact, the "half-shell" comprises more than half of the housing (it is perhaps more accurately described as a cover), but it is referred to as a half-shell for convenience. Figures 5 c and 5d show two such modules 17 connected together via interlocking end portions 18 and 19. Figure 5e shows the assembled modular half-shell 20 connected to another "half- shell" 21 (which is perhaps more accurately described as a base). Figure 5f shows the assembled protective housing containing an end block 5. This invention includes the concept, as shown in Figure 6 of the accompanying drawings which is largely self-explanatory, of supplying a bigger cover (10) with lid (20), which allows the user to upgrade the overclosure to a box able to contain a second inner closure e.g. in case a copper network is upgraded to an optical fibre network and a second closure is needed for an added optical fibre cable. Preferably the cover has a lid, so that the product can be made more easily accessible with less digging. This is especially desirable when the second cable is installed with overlength and can be taken out of the overclosure. Additional advantages of this design include: (a) the endblocks (30) are wraparound i.e. the overclosure can be installed on a ducted cable without cutting the cable; (b) this also allows one to install the overclosure without having to push back the ducts to fit them in a gland as is usually done in current designs; One can just lay them in the end block and close the block, thus making installation much easier because the ducts are very stiff to move around; (c) the use of portsplitters (40) incorporating, for example, rubber blocks, to terminate more smaller ducts in one bigger port.

Claims: CLAIMS : 1. A kit of parts for protectively enclosing an exposed splice between two or more cables that are carried in ducts, comprising: a) an inner cover for enclosing the exposed cable splice; b) a removable protective outer housing for completely enclosing the inner cover, the housing having at least one open or openable end to receive an end region of a duct carrying a spliced cable; and c) an end block for blocking the end of the housing around the end region of the cable duct. 2. An assembly of parts which protectively encloses an exposed splice between two or more cables that are carried in ducts, comprising: a) an inner cover which encloses the exposed cable splice; b) a removable protective outer housing which completely encloses the inner cover, the housing having an open end in which is received an end region of a duct carrying a spliced cable; and c) an end block which blocks the end of the housing around the end region of the cable duct. 3. A method of protectively enclosing an exposed splice between two or more cables that are carried in ducts, comprising: a) enclosing the exposed cable splice in an inner cover; and b) completely enclosing the inner cover in a removable protective outer housing such that an end region of a duct carrying a spliced cable is received in an open end of the housing, and the end of the housing around the end region of the cable duct is blocked by an end block. 4. A kit, assembly or method according to any preceding claim, in which the inner cover includes a seal which seals directly around the cables. 5. A kit, assembly or method according to any preceding claim, in which the end block, and preferably also the end region of the cable duct, is spaced apart from the inner cover in use. 6. A kit, or assembly or method according to any preceding claim, in which the end block is connected, preferably rigidly connected, to the inner cover in use. 7. A kit, assembly or method according to any preceding claim, in which the inner cover is substantially rigid. 8. A kit, assembly or method according to any preceding claim, in which the inner cover is formed from recoverable, preferably heat-recoverable, material. 9. A kit, assembly or method according to any preceding claim, in which the protective outer housing is moulded. 10. A kit, assembly or method according to any preceding claim, in which the protective outer housing is extruded. 11. A kit, assembly or method according to any preceding claim, in which the protective outer housing comprises a pair of half-shells which are connected together at least in use. 12. A kit, assembly or method according to claim 11, in which at least one of the half- shells of the protective outer housing is assembled from a plurality of modules. 13. A kit, assembly or method according to any preceding claim, in which at least a part of the end block, preferably substantially the entire end block, is separate from the housing. 14. A kit, assembly or method according to any preceding claim, in which the end block is substantially rigid. 15. A kit, assembly or method according to any preceding claim, in which the end block comprises a plurality of parts which are secured together around the cable duct in use. 16. A kit, assembly or method according to any preceding claim, in which the end block blocks the end of the housing around the end regions of a plurality of cable ducts. 17. A kit, assembly or method according to any preceding claim, further comprising a seal between the end region of each duct and the or each cable carried by the duct. 18. A kit, assembly or method according to any preceding claim, in which the end block grips the or each cable duct end region so as to prevent relative longitudinal movement between the housing and the cable duct in use. 19. A kit, assembly or method according to Claim 18, in which the end block includes at least one separate duct gripper to grip the or each cable duct in use.

Inventors: DAMS FRANCIS, ROOSEN DIRK, DAMS, FRANCIS, ROOSEN, DIRK
Applicants: DAMS FRANCIS, RAYCHEM LTD, RAYCHEM SA NV, ROOSEN DIRK, DAMS, FRANCIS, N.V. RAYCHEM S.A., RAYCHEM LIMITED, ROOSEN, DIRK
Application year: 1999
Main classification: H01R9
IPC codes: G02B6, H01R9, H02G3