IE44057B1 - Method and device for enclosing a cable splice - Google Patents

Abstract

The covering comprises a compressibly foamed plastic (24, 26), wound around the cables (12, 14) at a distance from the splice (10), and flexible film material (22) as a covering of the splice, which material is held securely on the compressibly foamed plastic (24, 26). The consequently enclosed cavity is filled by rigid-foamed plastic (46). This covering can be produced at low costs for labour and material, because the splice does not have to be fixed during curing; this is since the compressibly foamed plastic (24, 26) and the film material (22) form a housing in which the curing plastic (46) is pressed into all the cavities. Therefore, lashing errors are greatly reduced and any installation errors can be seen immediately and can be rectified.

Description

This invention is directed to a method of and device for gidly enclosing cable splices. More specifically, this mention is directed to a method of and device for providing cable splice ®closure.

Cable splice enclosures have found increasing use in derground utility applications. Splice enclosures for use derground need to be waterproof, impervious to insects, fungus d bacteria, and to be mechanically strong. To meet these rious stringent requirements, several types of cable splice closure systems have been devised. These systems generally ploy a rigid outer structure filled with waterproof material, e waterproof fillers generally employed have included nonrdening materials which are not miscible with water, powders, d resins which are cured in the enclosure. In the case of the n-hardening materials and the powders, it is necessary to ovide a rigid outer structure for structural support of the ble splice. Further, the outer structure is required, in such stances, to provide a continuing leakproof assembly to prevent osion and infestation of the non-rigid waterproofing material closed therein. Such leakproof, rigid outer structures require tailed assembly procedures including masking and taping the bles to either end of the structure, sealing the structure, d filling the structure with a waterproof compound. Because the required detailed assembly procedures, these final cable lice enclosures are generally expensive and may be ineffective cause of the high probability of installer error.

Where res .ins are employed for creating the moisture proof inner structure, other problems are encountered. The heat of the curing reaction may crack the curing resin and thereby reduce the rigidity and waterproof nature of the final structure. The use of resins also requires a substantial cure time, normally about minutes. During this cure, the splice must be held absolutely still to prevent the creation of passageways for water intrusion. Consequently, the use of resins prevents a high probability of installer error and also increases the cost of the splice enclosure.

Further, if the outer casing is not made leakproof, tiie resin tends to leak quickly from the casing before it begins to cure. The casings employed with potted resin enclosures must, therefore, present a backup structure for the resin to insure a rigid and waterproof splice enclosure. it is therefore an object of the invention to provide a method of and device for rigidly enclosing cable splices which overcomes or substantially reduces the above discussed disadvantages One aspect of the present invention provides a method of forming a cable splice enclosure comprising the steps of forming, around the cable splice and a portion of each spliced cable, a mould constructed of flexible sheet material and compressible material positioned between the flexible sheet material and the cables, providing a mastic ring about the sheath of each of the cables between the compressible material and the splice, adding a hardenable material to the interior of the mould, the hardenable material completely enclosing the splice and the portion of each cable in tiie interior of the mould, thereby forming a rigid enclosure around the cable splice.

Another aspect of the invention provides a cable splice enclosure comprising a mould around the splice filled with a hardenable material, the mould including a compressible material providing sealing contact with the cable ends entering therein; said enclosure also including a mastic ring about each cable between said compressible material and said splice.

The present invention provides an advantageous system for enclosing a cable splice to provide a rigid and waterproof structure in that it employs an outer structure or mould which need not substantially enhance the rigid and waterproof nature of the completed enclosure. The compressible material conveniently takes the form of compressible foamed plastics members positioned about the cables away from the splice. The mould is preferably a sheet naterial which is positioned about the cable splice and is caused to be sealed with the compressible material by its compressibility and resilience. The completed enclosure encloses a hardenable material surrounding and dispersed within the cable splice. When hardened, this material provides the structural support and waterproof nature of the completed cable splice enclosure. Resins which have been activated to cure to a hard structure nay be easily handled by such a temporary mould. Activated plastics which foams to form a rigid structure may also be advantageously employed with these non-structural outer cases or moulds. The use of plastics activated to foam also provides, when complete, substantial thermal insulation to the splice. The flexible sheet material and the flexible foamed plastics material become unnecessary as structure or waterproofing components of the enclosure.

In a preferred embodiment, because foamed plastics material is wrapped about the cables at the end or ends of the mould or case which is compressible and resilient, the outer sheet forming the mould may be quickly and easily forced around the foamed plastics to form the seal which will prevent leakage of resin or foaming plastics during formation of the inner structure. The 4 0 5? assembly time for the splice enclosure is substantially reduced because the activated plastic forms within a few minutes. Activated resin closures may be left to cure without fear of leakage. Further, when foaming plastics is used, the foam tends to flow until it finally becomes rigid. Consequently, it is not necessary to absolutely fix the splice during the curing of the plastics. Because of the simplicity of the structure and the ability of the foam to expand into all cavities, the probability of installer error is greatly reduced and any errors in installation become immediately apparent or are overcome by the action of the foam.

As a result, the overall cost of both labour and material is greatly reduced. Thus, the present invention provides substantial advantage over the heretofore employed non-hardening and resin enclosure requiring a rigid case and seals fabricated from mastic and tape.

A preferred embodiment and method of the invention, will now be described, by way of example only with reference to the accompanying diagrammatic: drawings, in which:Figure 1 is an exploded view of a splice enclosure of the 20 present invention when used to enclose a splice in a linear cable.

Figure 2 is a front view of the enclosure of Figure 1 but with a sectioned portion for clarity.

Figure 3 is a front view of an enclosure of the invention 25 when used to enclose a splice of two adjoining cables.

Figure 4 is a side view of the enclosure shown in Figure 3.

Figure 5 illustrates another enclosure of the invention which incorporates the use of resin.

Figure 6 illustrates an enclosure of the invention which 30 may be re-entered at a later time. ,405 Turning first to the embodiment shown in Figures 1 and 2, there is shown a splice 10 of cables 12 and 14. The splice is formed from incoming wires supplied by cables 12 and 14 which are individually connected through wire splices 16. A shield connector 18 is also provided. The splice 10, cables 12 and 14 and the shield connector 18 may all be of conventional design and construction.

The assembled cable splice is then enclosed by the cable splice enclosure. In this first embodiment, the cable splice enclosure comprises a flexible outer jacket generally designated 20 which includes a flexible cover 22 and compressible end seals 24 and 26. When applied about the cable splice, the jacket 20 provides a closed internal space about the cable splice 10 and the ends of the cables 12 and 14.

The flexible cover 22 may most conveniently include a poly ethylene tube. This polyethylene tube is folded in half to form a two-layer sheet 28 and tacked together along lines 30 and 32. This tacking may be accomplished by running a heated element along these lines. The rectangular sheet 28 thereby formed is flexible and can provide substantial tensile strength. The tacking along lines 30 and 32 is primarily for convenience.

Bars 34 and 36 can be conveniently located between the tack lines and the folds of the tubing. The bars 34 and 36 when positioned in the edges of the rectangular sheet 28 provide a rigid structure for closing the jacket 20 about the splice 10.

To hold the bars 34 and 36 together, slots 38 are provided through the bars 34 and 36. The slots 38 are aligned to receive fasteners 40. The fasteners 40 are preferably pointed at a first end to allow penetration of the polyethylene tubing at the slots 38. A thin section 42 is provided near the center of the fasteners 40 to allow rotation of the fasteners 40 in the slots 38. The broader end sections of the fasteners 40 are then unable to withdraw from the bars 34 and 36. The bars 34 and 36 and the fasteners 40 are preferably of strong plastics or metal to resist the tension forces placed in the flexible sheet 28 by the expanding foam described below. The number of fasteners 40 and slots 38 depend on the rigidity of the bars 34 and 36, the expected pressure of the expanding foam placed within the jacket and the length of the enclosure.

The compressible end seals 24 and 26 are secured to the inner side of the flexible sheet 28 at respective ends thereof. Epoxy or other bonding substances may be employed to fix the end seals onto the flexible sheet 28. The end seals 24 and 26 are preferably of a compressible foamed plastics such as polyurethane or expanded neoprene which is also resilient in order that the compressed material will expand to tightly seal against the cables and the enclosure when the bars 34 and 36 are brought together. In order that the end seals 24 and 26 do not interfere with the joining of the bars 34 and 36, the end seals 24 and 26 need only extend to points near the weld lines 30 and 32. It is advantageous that the height of each end seal 24 and 26 is such that when the bars 34 and 36 are joined, each end seal 24 and 26 will be compressed about the cables 12 and 14. The width of each end seal 24 and 26 is preferably such that the seal cannot be readily pushed over to allow escape of the expanding foam placed within the jacket. End seals having a width equal to twice the thickness have been found to be quite satis factory.

These flexible and compressible foamed plastics end seals 24 and 26 replace the use of conventional mastic and tape. The resiliency and compressibility of the flexible end seals 24 and 26 make possible the easy assembly of the flexible plastics sheet 28 and the spliced cables 12 and 14. The conventional ι40ΰ7 method for sealing open ends between a casting and spliced cables is to first apply mastic, force the casing over the mastic, add more mastic, and finally cover the entire area with tape. This procedure requires skill and quite a bit of time. Further, a good closure is not guaranteed especially in cold weather when the mastic is not sticky. The end seals 24 and 26 are not intended to prevent moisture intrusion, but rather co-operate with the remainder of the enclosure system to define the outer limits of the rigid foamed plastics later positioned within the enclosure.

Plastics 44 is activated to foam and is then poured into the jacket 20. The activated plastics is allowed to foam to fill the space formed by the jacket 20 when the spliced cables are in the jacket. The spliced cables nay be placed in the jacket 20 either before or after the activated plastics 44 is poured therein. After the plastics 44 has been poured into the jacket 20, the bars 34 and 36 are brought together and held together by the fasteners 40. The activated plastics 44 is then allowed to expand to fill the interior space. It is advantageous to place enough activated plastics 44 in the jacket 20 so that the resulting rigid foamed mass 46 will more than fill a space equal to the interior space of the jacket if allowed to freely expand. By using more plastics 44 than is required to just fill the jacket 20, the resulting density of the foam 46 will be greater. This adds structural strength and reduces the chance of leakage. Further, it enhances the intrusion of the foam into the splice itself. Once the foamed mass 46 is cured, the jacket 20 is no longer required. However, it may be left on the enclosure for convenience and for whatever added protection it may provide. The time required for the rigid plastics mass 46 to expand and strengthen may be set for approximately 10 minutes. This is far better than the 45 minutes which is often required for resin to cure and strengthen. Rigid 4 0 S 7 polyurethane foam or an equal mixture of polyol and isocyanate can be used to form the mass 45.

To enhance the density of the rigid foamed plastics 46 and to promote the intrusion of the foaming plastics 46 into the splice 10, a porous pad 48 may be positioned within the jacket 20. The pad 48 may be a coarse, open-celled, foamed plastics structure such as used for air filters. This pad 48 is placed about the position where the cable splice 10 will be located in the jacket 20. The activated plastics 44 may then be poured over this pad 48 and the jacket 20 closed. Because of the open-celled nature of the pad 48, the activated plastics 44 will permeate the pad and flow to the flexible sheet 28 of the jacket 20. When the jacket 20 is closed, the pad 48 will be bent around to meet itself and provide a semi-continuous support about the splice 10. The activated plastics 44 will expand about and within the pad 48. The pad 48 will resist this expansion and thereby increase the final density of the foamed plastics mass 46. During expansion of the activated plastics 44, the foaming substance is moved by the foaming pressure within itself. Under the restraint of the pad 48, the foaming substance will be driven by itself into the cable splice 10 to fill all cavities. The pad 48 also provides some strength to the enclosure.

To facilitate the assembly of this enclosure, rigid, yet malleable spacers may be included. Only one such spacer 49 is shown; however, two spacers 49, one on each end, are suggested. The spacer 39 is divided at one end into two prongs. These prongs are illustrated in Figure 1 before assembly. During assembly of the enclosure, the pronged end of each of the spacers is bent around the cable as seen in Figure 2. Thus, the spacer will be maintained during assembly of the enclosure relative to the cable and splice. At the end opposite the pronged end, a fastener 50 may be employed to attach the spacer to the bars 34 and 36. In this way, the spacer 49 will maintain the bars 34 and 36 at a convenient position relative to the cables 12 and 14. In order that the spacers will be easy to work with, they may be made conveniently from aluminium.

To insure a proper seal along cables with polyethylene covers, mastic is positioned in rings 51 and 52 about the cables 12 and 14 on either side of the splice 10. These mastic rings 51 and 52 are positioned so that they will be within the fcamed plastics mass 46. The mastic used may be any one of the commercially available mastics such as uncured butyl rubber. The mastic rings 51 and 52 tend to adhere well to the rigid foamed plastics mass 46 and also to the polyethylene cover on the cables 12 and 14. A barrier is thereby provided which prevents moisture intrusion between the rigid foamed plastics mass 46 and the cables 12 and 14.

This first embodiment may also be constructed to allow reentry into the splice. Such a configuration is illustrated in Figure 6 and includes a flexible plastics sheet 54 wrapped about the splice 10 and held at either end by rubber bands 56 or other· wise as preferred. Two rip wires 58 are then positioned on either side of the cable splice 10. These rip wires may be of 20 gauge stainless steel wire. Stainless steel is suggested because of its longevity in underground environments. The rip wires 53 may be held down by the rubber bands 56. The rip wires 58 also extend through the mastic rings 51 and 52 to prevent leakage along the rip wires 58. The enclosure may then be assembled in a conventional manner. When re-entry is required, the jacket 22 can be removed and the rip wires 58 drawn through the rigid foamed plastics mass 46. The inner wrapping of - 11 plastics sheet 54 is .then exposed and can be easily removed to gain access to the splice. The rip wires shown in Figure 6 are displaced from the sheet material 54 for clarity. However, it is preferred that the wires lie directly on the plastics sheet 54 in order that all of the rigid foamed plastics material 46 may be cut.

A second, less complicated jacket may be employed with a cable splice which connects two adjacent cables as illustrated in Figures 3 and 4. Two cables 60 and 62 extend to a splice 64.

A shield connector and clamp 66 connects the two cables 60 and 62 together. Such a splice may be used in an underground cable line where each end of the cables to be spliced can be brought together as shown in Figures 3 and 4.

The cables 60 and 62 are wrapped with the compressible foamed plastics material used in seals 24 and 26. A seal 63 is thereby provided. The compressible foamed plastics material is preferably placed between the cables 60 and 62 as ‘well as around these cables to form an adequate seal, the material thus being generally in the form of a figure eight. A flexible plastics tube 70 is positioned over the splice 64 and is gathered at the seal 63. A conventional tie strip 72 is then placed about the seal 68 and the gathered tube 70. A seal is thereby formed between the tube 70 and the cables 60 and 62. This seal is not impervious to water but provides a strong seal to prevent the flow of the foaming plastics material along the cables.

A plastics sack 74 is also incorporated with this enclosure. The plastics sack 74 and the tubing 70 may both be of polyethylene film. The sack 74 and the tubing 70 are conveniently of the same expanded diameter in order that the tubing 70 and the sack 74 will both come to resist radial expansion of the foam at the same time. As with the first embodiment, the tubing 70 and the sack 4 0 5 7 - 12 74 primarily operate as a mold for the rigid foamed plastics which is expanded in the enclosure.

With the seal 68 completed, activated plastics is poured into the interior of the tubing 70. The plastics is not shown, for clarity. The tubing 70 is then folded over at 75 and the sack 74 is positioned over the assembly. The sack 74 is pulled all the way down to the fold 75 in the tubing 70. As the activated plastics begins to foam, it will initially expand to meet the tubing 70 and the sack 74 at the lower end of the enclosure near the seal 68. When the foam begins to exert pressure against the inner sides of the tubing 70 and the concentrically arranged sack 74, the sack will be held by friction from slipping upward and off the tubing 70. The expanding foam is then forced upward by the lateral constraint of the tubing 70 and the sack 74. The foam will eventually rise to the fold 75 in the tubing 70 and begin to force the fold out of the tubing 70. This unfolding of the tubing 70 is resisted because the folded portion of the tubing 70 is held between the lower portion of the tubing 70 and the side of the sack 74. The foam is also exerting radial pressure against the inner side of the tubing 70 which acts to hold the fold in place and keep the plastics sack 74 down on the tubing 70. Vent holes 76 are provided at the top of the plastics sack 74 in order that gas pressure cannot build up in the sack 74 and permaturely force it off the tubing 70. The co-operation of the tubing 70 and the sack 74 to hold the fold in the tubing 70 and to hold the sack down on the tubing causes the rigid foam to expand within a constrained volume. This acts to increase the density of the foam for greater strength and impenetrability. The expanded enclosure is shown in phantom in Figures 3 and 4. In some cases it may not be necessary to employ the sack 74? the tubing along being sufficient to form the splice enclosure. This is especially true where activated resin rather than foaming plastics is poured into the tubing 70. 4 0 5 7 - 13 As with the embodiment illustrated in Figure 1, a porous pad 78 may be employed to further increase the density of the foam, cause the foaming material to penetrate the splice 64, and strengthen the overall enclosure structure. The pad 78 is preferably provided with a hole at 80 and is positioned over the ends of the cables 60 and 62. The mesh pad 78 may be positioned before the splice 64 is made. When the pad 78 is positioned first, a smaller hole or holes are required in the center of the pad 78.

A bead of mastic 82 is also employed about the cables 60 and 62 near the seal 68. The mastic adheres well to the polyethylene covers on the cables 60 and 62 and becomes embedded in the resulting rigid foamed plastic enclosure. The mastic thereby prevents water intrusion at the inner face between the cables 60 and 62 and the rigid foamed plastic mass.

A third embodiment is illustrated in Figure 5. Again, a seal 84 is formed about the cables 86 and 88 by threading a piece of flexible, compressible, foamed plastics material around the cables 86 and 88. The cable and seals are then jammed into the hole located at 90 in the pliable plastics enclosure 92. Resin 94 may then be poured into the enclosure 92 and allowed to cure. In this application, a conduit 96 is shown extending upward about the splices 98 and 100 to meet cables 102 and 104.

On all three embodiments, a seal is provided about the cables which is designed to prevent the flow of the internal sealing material and is not specifically designed to prevent moisture intrusion. Further, the jackets and outer enclosures act primarily as molds for the placement of foaming plastics.

In the first two embodiments, these molds further operate to constrain the expansion of the foaming plastics to increase the final density of the rigid foamed plastics mass which forms the 440 57 cable splice enclosure. Thus, in preferred embodiments of the present invention, the outer casing or jacket structure may be of inexpensive and easily worked materials. The inner structure formed by the foamed plastics provides the structural rigidity and imperviousness necessary for underground cable splice enclosures . Once the splice is completed, the enclosure inall instances may be quickly and easily provided and the foam added and cured in substantially less time than it takes for the resin in conventional enclosures to cure.

While embodiments and applications of this invention have been shown and described, it would be apparent to those skilled in the art that many more modifications are possible without departing from the invention as defined by the appended claims.

Claims (20)

1. CLAIMSιΙ. A method of forming a cable splice enclosure comprising the steps of forming around the cable splice and a portion of each spliced cable, a mould constructed of flexible sheet 5 material and compressible naterial positioned between the flexible sheet material and the cables, providing a mastic ring about the sheath of each of the cables between the compressible material and the splice, adding a hardenable material to the interior of the mould, the hardenable material completely enclosing the 10 splice and the portion of each cable in the interior of the mould thereby forming a rigid enclosure around the cable splice.

2. A method as claimed in Claim 1, wherein the compressible material is wrapped completely around each cable where each cable enters the mould. 15

3. A method as claimed in Claim 1 or Claim 2, wherein the hardenable material is an activated formable plastics material which foams to fill the interior of the mould after its addition.

4. A method as claimed in any one of Claims 1 to 3, wherein the compressible material is a flexible foamed plastics 20 material.

5. A method as claimed in Claim 3 or Claim 4, wherein the compressible material is positioned axially on either side of the cable splice.

6. A method as claimed in Claim 4, wherein the flexible 25 sheet material is a piece of flexible tubing, one end of which is secured against the compressible material to provide the mould, the portion of the tubing adjacent the other end being folded over to close the mould.

7. A method as claimed in Claim 6, wherein a plastics 30 envelope is placed over the flexible tubing. - 16 4

8. A method of forming a cable splice enclosure substantially as herein described with reference to the accompanying drawings.

9. A cable splice enclosure comprising a mould around the splice filled with a hardenable material, the mould including a compressible material providing sealing contact with the cable ends entering therein, said enclosure also including a mastic ring about each cable end between said compressible material and said splice.

10. An enclosure as claimed in claim 9, wherein the compressible material between the mould and the cable ends comprises compressible foamed plastics material wrapped around the cables and spaced from the splice.

11. An enclosure as claimed in Claim 10, wherein the mould comprises a piece of flexible tubing gathered at one end about said compressible foamed plastics material and positioned so as to form the seal between the mould and the adjacent cable ends, the other end of the piece of tubing being folded over and held by an enclosing member to provide said closure means.

12. An enclosure as claimed in Claim ll, wherein the mould is contained within an envelope forming said enclosing means, the flexible tubing and said envelope having substantially the same expanded diameter.

13. An enclosure as claimed in Claim 9 or claim 10, wherein flexible sheet material is wrapped around the splice.

14. An enclosure as claimed in Claim 13 comprising at least one rip wire extending along the cables, the or each wire extending between the cable splice and the flexible sheet material wrapped around the splice.

15. An enclosure as claimed in any of Claims 10 to 12, - 17 44 057 wherein the splice within the mould is enclosed within a porous pad of resilient material.

16. An enclosure as claimed in Claim 12, wherein the envelope has at least one vent hold located therein adjacent 5 its closed end.

17. An enclosure as claimed in any of Claims 10 to 16 comprising means for forcing the mould tightly against the seal

18. An enclosure as claimed in any of Claims 10 to 17, wherein the mould is a flexible sheet material. 10

19. An enclosure as claimed in any of Claims 10 to 17, wherein the mould is a flexible tubing.

20. A cable splice enclosure substantially as herein described with reference to Figures 1 and 2 or Figures 3 and 4 or Figure 5 or Figure 6 of the accompanying drawings.