Installation of Cable Sleeves | Jointing & Splicing Cables
Published 17 Jan 2020
Installation of Cable Sleeves
The pulled in cables are not always long enough to join together two connection points without interruption. Sometimes the position and type of laying run require the use of separate lengths of cable.
For reasons of cost and space there-fore the simple lengthening of a cable is usually achieved with cable sleeves. Junctions from the cable or division of a cable into several continuing cables must be carried out with suitable distributing boxes. The connection of two or more cables within boxes or cable sleeves must be undertaken with the greatest care and be protected from dampness or moisture.
A tent must be erected for the duration of the installation. Work on the sleeve and box should be undertaken quickly and without interruption.
On the below Draka provide a verbal and pictorial description of the procedure for installing a sleeve. Please note in every case the parameters of the sleeve manufacturer, the information sheets of the cable manufacturer, as well as the safety regulations of the network operator.
LV MV HV Cable Preparation
Preparation begins with the choice of the correct sleeve for the corresponding cable.
For our example we have chosen a signal cable with reduction factor of the type Draka SIGDRAK® AJ-2Y(L)2YDB2Y 3x4x1.4 (H45) rk-group 500 as well as the matching connecting heat-shrinkable sleeve and protective heat-shrinkable sleeve.
Although Draka carried out the installation indoors, the same procedure applies outdoors: both cable ends must be fixed to cable stands or similar devices in such a way that the work environment is clean, tidy and protected from moisture. The cable ends should generously overlap the external edge of the sleeve.
➡ Recommendation: feel free to allow a little extra here.
Removal of the Cable Sheath
Removal of the outermost protective cable sheath must take place according to the instructions of the sleeve manufacturer.
Removal of the Armouring
Removal of the armouring (steel band) occurs according to the stipulation of the sleeve manufacturer. When sawing into the steel band the shielding wires lying beneath must not be damaged. For thick cables and thick steel bands it is possible to use an iron saw with a depth marker. In our case a simple small hacksaw also served the purpose.
The upper layer of steel band is sawn into and can now be carefully unwound using a pair of pliers. Please take care with sharp edges and points: danger of injury!
The same procedure is followed with the second layer of steel band. Please pay careful attention here in particular to the intactness of the shielding wires which lie beneath.
The opposite cable end is to be prepared as appropriate.
The shielding wires are also shortened according to instructions. Then there are two possibilities: armouring and shielding wires can now be connected immediately or, as in our example, at the end after the connecting heat-shrinkable sleeve has been installed.
Making Contact with the Laminated Sheath
The inner laminated sheath is carefully stripped to the prescribed length. Damage to the core layers below can reliably be avoided by using a special stripping tool.
An incision is made in the remaining laminated sheath in two places at a maximum distance of 15 mm apart, each cut being 30mm long. The resulting folds in the sheath are carefully bent upwards .In the picture on the right the laminated sheath, drain wire and plastic film are fixed with some plastic tape.
The V-clip of the shield continuity wire is laid sideways around the edge of the cut fold of cable and closed tightly with combination pliers. In this way the teeth on the clip cut through the cable sheath into the aluminium band. A secure contact is thus guaranteed.
Then the V-clip and laminated sheath are wrapped with three layers of plastic tape. The drain wire can be cut off or additionally wrapped around the clip. If necessary please note any supplied customer instructions for this.
Once the cores have been spliced, the shield continuity wire is lined up, without the spare loop, straight along the splice, where it is connected as appropriate with the laminated sheath of the second cable.
Splicing the Cores
When splicing the copper cores the correct stranding order must be observed. In our case the tracer quad is suitably clearly marked by knotting the thin blue plastic tape.
The cores are individually stripped of insulation with the help of a suitable cable stripper. Please take care that the copper conductors do not become soiled or damaged or exposed to dampness or moisture.
Both stripped core ends are connected with a crimp splice and joined together with a pincer to be tension-proof. Please be absolutely certain to follow the correct coding and sequence of the cores and quads to be connected. Errors are usually not discovered until the final check or first operation and lead to costly correction measures.
After installation the crimp splices are carefully shrunk with a burner. Released glue and the closely fitting plastic protect the bare copper joint mechanically and against dampness.
This is what the splices look like following successful shrinkage. When a connection has been shrunk correctly, some glue will seep out at the sides.
Staggered splices result in a narrow joint. If you have not already done so, you should now connect the shield continuity wire with the laminated sheath of the opposite cable.
Preparation of the Inner Connecting Heat-shrinkable Sleeve
The two laminated sheaths facing the core splices are now cleaned with a cleansing cloth so that a 150 mm wide area is oil-free.
Once the oil has been removed the laminated sheath is roughened across the cable axis with an emery cloth. Any pitted areas in the sheath must also be roughened.
Following this the cleaned and roughened areas are heated with a burner until they are hand-hot.
Before installation of the actual heat-shrinkable sleeve, the drying agents supplied with the packaging should be fixed around the core splice with adhesive tape.Please do not wrap the entire drying agent with isolating tape as this will prevent it from fulfilling its function. Simple wrapping to keep the agent in place is sufficient.
The protective padding should be rolled together before the installation (pre-formed) and then laid as tightly as possible overlapping the core splice and secured with adhesive tape.
The lamellar areas of the protective padding should be unwound with adhesive tape.
Line up centrally the seal for the heat-shrinkable sleeve. It must extend beyond the protective padding by the same length on each side.It is helpful to mark at least on one side of the laminated sheath how far the seal will extend.
When shrinking the sleeve, begin in the middle. For this procedure heat the complete area of the sleeve and shrink it towards one end. Then work on the other end. Move the flame back and forth evenly and continuously to avoid localised burning.
The shrinking process is over when the seal has evenly shrunk, the green colour pigment in the sleeve material has disappeared and the white indicator line is easily visible under the sealing edge. At the ends small amounts of glue must be seeping out of the cable.
Caution: the shrunken seal and the sealing edge retain the heat for a very long time (danger of burns!). As it cools the sleeve shrinks a little further.
Connecting the Cable Armouring
Before connecting the armouring and the shielding wires, the exposed areas of the latter should be cleaned metallically bright and roughened. When doing this, please also heed the armouring layer beneath.
The copper fabric tape should be wound according to instructions in a single layer around the armouring and shielding wires. The remaining fabric tape should be cut off and retained.
The supplied contact plates are pre-formed according to instructions, laid around the copper fabric tape and wrapped and secured with one layer of the copper fabric tape (with a max. 5 mm overlap).
The earth wire is cut to 1.5 times the length of the removed section of the outer protective coating, and pulled over the neighbouring protective tube in such a way that approximately 100 mm are left bare and free at both ends of the earth strand. The end of the earth strand is fanned out and, flush with the removed edge of the armouring, laid flat onto the copper fabric tape and secured close to the end of the removed edge with a roll spring. The earth wire is fixed with the second roll spring with three layers, then pulled back and secured with the remaining layers of the roll spring.
At the end of installation the earth wire looks like this. The second side should be dealt with in the same way.
Installation of the Protective Wrap
Before the protective wrap is fitted the external protective coating must be cleaned, roughened and warmed. The whole contact area is preheated using heat shrink gas torch, before the shrink tape (protective wrap), starting with the PE-sheath between the inner sleeve and roll spring, is tightly wrapped half-overlapping the whole contact area up to the outer sheath. The area where the earth wire protrudes is excluded as little as possible. A maximum of half the width of shrink tape should be placed on the protective coating.
The protective wrap is heated with a low flame until the tape shrinks and glue seeps out at the overlaps.
The shrunken tape and the seeping glue should be clearly visible.
Installation of the Protective Heat-shrinkable Sleeve
The earth wire is laid radially around the splice and secured with some plastic tape. Then the metal protective padding should be tightly laid around the inner sleeve, centrally and overlapping, and secured with adhesive tape. The conical ends should be carefully wrapped with plastic adhesive tape.
The outer sheath is cleaned until it is oil-free, roughened across the cable axis and then heated with a low flame to hand-hot temperature.
The wrapping on the conical ends of the metal protective padding should be clearly visible.
The seal for the heat-shrinkable sleeve is laid centrally over the connecting point and the projection marked on at least one side of the laminated sheath.
The flame-retardant foil (self-adhesive aluminium foil) is attached so that it is laid over the marked line approximately 10 mm towards the inner sleeve. In this way it reaches a maximum of 10 mm into the sleeve, whilst the greater part of the foil remains outside the heat-shrinkable sleeve. The foil should be smoothed over with a blunt tool, for example the smooth handle of a pair of pliers or the handle of a hammer.
The heat-shrinkable sleeve is placed centrally around the metal protective padding and closed on both sides with the sealing edges. The connection clip is placed between both ends of the sealing edges in the centre of the sleeve.
Before shrinkage the sleeve should be centred. The two flame-retardant foils which reach slightly into the sleeve on both sides may serve as orientation.
When shrinking the sleeve, begin in the middle. For this procedure heat the complete area of the sleeve and shrink it towards one end. Then work on the other end. Move the flame back and forth evenly and continuously to avoid localised burning. Heat the shrink seal until the green dots on the seal have turned black.
It should be easy to recognise that the green dots on the seal have almost completely disappeared. Glue will leach slightly out of the sleeve end lying on the flame-retardant foil. The white indicator line under the sealing edge is clearly visible. The protective heat-shrinkable sleeve is correctly closed and is water-tight. As it cools it will shrink a little further.
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Thorne & Derrick distribute an extensive range of Cable Pulling & Laying Equipment to enable the safe installation of fibre and copper cables within the telecommunications industry. Safely installed cables reduces operational and maintenance requirements to the network and reduced service interruption to telecom cables, wires, ducts, cabinets and exchanges – products include cable spiking tools, conduit rods, cable lubricant, cable socks and rollers.