Cable Pulling & Laying

Installation of Rail Foot Cables

January 20th, 2020

Installation of rail foot cables

Installation

Lay the cable down outside the area of the tracks and align it.

When doing so the cable must not be unwound over the flange of the delivery drum. In that case loops will occur which cannot be compensated during the lay. Lay the cable along the external side of the rail foot. When installing the cable, ensure that there is a reserve length of approximately 5 metre on each side.

If local conditions are met, the cable may also be laid directly along the external side of the rail foot from a slow moving railcar. Installation of the rail foot cable and fastening to the rail foot should take place from one end only or from the middle towards both ends. If installation is attempted from both ends, loops will occur in the cable. In this case damage to the cable by passing trains could not be ruled out.

At earthings, points, track magnets, level-crossings or in the case of a necessary joint the rail foot cable should be led away from the track with the help of a rail foot junction authorised and released by the rail operator. The cable should then be laid in the ground or in cable troughs, or at least be placed inside a protective pipe. For this procedure the minimum bending radius of the cable, as stipulated by the manufacturer, must be observed.

The placing of cable joints directly at the rail foot is not permitted.

Instead the cable ends to be joined must be led away from the rail foot and brought together in a sleeve next to the tracks.

Ideal installation of rail foot cables

Inadequate installation creates loops

Fastening Cables

The cable may only be fastened with rail foot clamps which are approved for the particular type of track, since the permissible downward pressure is dependent on the type of cable and the track shape.

We recommend allowing one rail foot clamp in at least every second sleeper spacing and never fitting more than one single cable under the rail foot clamps at the rail foot.

In principle the installation of two rail foot cables under one rail foot clamp is possible. Special attention need to be paid to the diameter of the cable and the guidelines of the manufacturer of rail foot clamps. A combination of very small with larger rail foot cables shall be avoided as the expansion of both cables due to temperature changes are different and will result in loops. Furthermore the smaller cable shall always be installed on top.

Inadequate installation creates loops of the lower cable

Installation of Rail Foot Cables

Cable Pulling Equipment

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.

Installation of Cable Sleeves | Jointing & Splicing Cables

January 17th, 2020

It should be easy to recognise that the green dots on the seal have almost completely disappeared

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 cable sheath

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.

Removal of the armouring

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 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.

The shielding wires are also shortened according to instructions

Cutting shielding wires

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.

Making contact with the laminated sheath

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.

An incision is made in the remaining laminated sheath

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.

V-clip of the shield continuity wire is laid sideways around the edge of the cut fold of cable

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.

Once the cores have been spliced, the shield continuity wire is lined up

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.

Splicing the cores

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.

Cores are individually stripped of insulation

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.

Both stripped core ends are connected with a crimp splice

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.

After installation the crimp splices are carefully shrunk with a burner

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.

This is what the splices look like following successful shrinkage

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.

Staggered splices result in a narrow joint

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.

Preparation of the inner connecting heat-shrinkable sleeve

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.

Laminated sheath is roughened across the cable axis with an emery cloth

Following this the cleaned and roughened areas are heated with a burner until they are hand-hot.

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.

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.

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 connecting heat-shrinkable sleeve

The lamellar areas of the protective padding should be unwound 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.

Line up centrally the seal for the heat-shrinkable sleeve

The seal is laid completely around the splice and the sealing edge pulled up.

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.

When shrinking the sleeve, begin in the middle

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.

The shrinking process is over when the seal has evenly shrunk

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.

Connecting the armouring

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 copper fabric tape should be wound according to instructions

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 supplied contact plates are pre-formed according to instructions

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.

The earth wire is cut to 1.5 times the length of the removed section of the outer protective coating

At the end of installation the earth wire looks like this. The second side should be dealt with in the same way.

At the end of installation the earth wire looks like this

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.

Installation of the protective wrap

The protective wrap is heated with a low flame until the tape shrinks and glue seeps out at the overlaps.

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.

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.

Installation of the protective heat-shrinkable sleeve

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 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 wrapping on the conical ends of the metal protective padding should be clearly visible

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 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

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.

The heat-shrinkable sleeve is placed centrally around the metal protective padding and closed on both sides with the sealing edges

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.

Before shrinkage the sleeve should be centred

When shrinking the sleeve, begin in the middle

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.

It should be easy to recognise that the green dots on the seal have almost completely disappeared

Cable Pulling Equipment

Cable Pulling | Safe Pulling of Cables Using Manual Laying

January 17th, 2020

Cable Pulling | Safe Pulling of Cables Using Manual Laying

Manual Laying

For manual pulling in of the cable one thing that must be ensured is that the cable is on no account pulled over the flange of the cable drum.

If the cable needs to be pulled in in sections, due to local conditions, no rings (image 1) may be laid, since this means that the cable is inappropriately twisted by 90°. Combined with high forces of tension and various deflections this can lead to destruction of the protective coating (image 2).

The formation of loops can easily be seen in the above pictures. In narrow cable shafts and when being pulled the cables are exposed to considerable torsion, which can lead to severe damage of the cable (image 1 on left).

If the cable is to be laid out in sections this may only occur in so-called ‘figures of eight’ (image 2 on the right), which are set out according to the cable diameter (note the bending radius!). Torsion of the cable can then no longer occur.

Image 1 – Safe Pulling of Cables Using Manual Laying

Image 2 – Destruction of the protective coating

Press Release | Thorne & Derrick Appointed Approved Stockist for UK Leading Cable Pulling Equipment Manufacturer

Cable Pulling Equipment

Cable Pulling | Safe Pulling of Cables Using Motorised Pullers

January 16th, 2020

Cable Pulling | Safe Pulling of Cables Using Motorised Pullers

Pulling with motorised assistance

In most cases the cable is pulled with motorised assistance. During this procedure, forces of tension result, which, depending on the type of LV MV HV cable to be pulled, can reach double kN figures. Particular attention must therefore be paid to work safety.

Trained staff and faultless equipment which is regularly checked and maintained should be a matter of course in order to guarantee safe operation. Damaged pulling ropes or bent hooks should be removed and replaced with safe ones.

Pulling of the cable should occur with constant monitoring of the connected tension gauge.

Suddenly increasing tension levels may indicate that the cable is obstructed or has become caught in the cable duct. Operators must reduce the speed of the cable winch or stop it in order to identify the cause.

While the cable is being pulled it must be ensured that the cable is running over the installed deflector rolls. Instances of cable damage occurring as a result of edges, corners or stones, or vehicles driving over the cable, are to be avoided at all costs.

The complete cable pulling process should be recorded in a protocol and any anomalies or irregularities should be noted. The tension measurements should also be added.

Once cable pulling is complete, the run should, where possible, be inspected again.

The cable end caps should once more be checked to ensure that they are securely fixed and watertight and should only be opened in preparation for a connection or the fitting of cable sleeves.

Cable Pulling Protocol for Low & High Voltage Cables

The protocol of tension measurements, which contains readings of the tension that occurred during pulling in, is essential to demonstrate that pulling in has been carried out correctly. If such a protocol can not be provided or if too high tension has occurred, the cable manufacturer will indicate incorrect laying and suspend the guarantee for any resultant damage.

In all cases the laying instructions of the customer and the cable manufacturer are to be observed, especially the data referring to bending radius and tensile strength.

Caterpillar Tracks

Where there is sufficient space it is possible to use underground cable caterpillar tracks, which support the pulling of the cable by pushing it along with a motorised caterpillar track system. Versions with electric motor, hydraulic drive or internal combustion engine allow the use of an underground cable caterpillar track irrespective of location.

When pulling outdoor cables in cable pipe with narrow cross sections the use of cable lubricating grease should be considered. Static friction between the cable sheath and the pipe walls is minimised by the grease, which makes it easier to pull the cable into the pipe.

Press Release | Thorne & Derrick Appointed Approved Stockist for UK Leading Cable Pulling Equipment Manufacturer

Cable Pulling Equipment

How to Prepare Cables To Avoid Cable Damages & Faults

January 16th, 2020

How to Prepare Cables To Avoid Cable Damages & Faults

Preparation of Cable & Run

A careful preparation of cable, cable drum and run can avoid a number of potential reasons for damages and faults.

Low & High Voltage Cables

Cables to be laid outdoors are usually delivered on large wooden or steel drums.

Manual laying of cables is not possible due to the excessive weight.

The cable drums are therefore placed in an uncoiling stand by crane or hydraulically. This stand can either be erected on a HGV trailer or separately, as seen in the picture on the right. The cable drum must have sufficient clearance from the ground and be able to turn freely.

The rolling direction marked on the drum must be observed.

Rolling against the rolling direction results in the loosening of the cable on the reel, which impedes uncoiling. The cable is always uncoiled at a tangent. A cable must NEVER be uncoiled over the flange. The resultant torsion can irreparably damage the cable.

This is equally true for indoor cables coiled on small and light plywood reels and for ring-wound goods.

Before laying the cable, check whether the cable ends have been correctly capped and are undamaged. Missing or improperly glued caps can lead to moisture penetration during transport or laying. The same applies to any damage to the external sheath or insufficient pressure in the case of pressurised telephone cables. Moisture in the cable generally causes deterioration in the insulation resistance and the operational capacity.

A visibly damaged cable must therefore not be wound without closer inspection and clarification of the causes.

Due to their sometimes excessive weight, outdoor cables usually can not be wound by hand. Appropriate winding aids, available in diverse motorised versions, should therefore be used. Make sure that it is possible to provide evidence of the pulling in forces (tension protocol)!

There are numerous possibilities for fastening a pulling rope to a cable and this should be chosen to suit the cable type. For telecommunications cables we recommend conductor pulling with a cable pulling head.

In our example we have used a cable sock. The fastening of the pulling rope to the cable must be undertaken with care to avoid ‘losing’ the cable on the way. Corners and edges at the cross-over point from cable to rope are to be avoided otherwise the cable can easily become stuck on ledges or bumps underground. Guide swivels should be used between the cable sock and pulling rope.

The choice of the correct cable grip is dependent on the diameter of the cable.

Press Release | Thorne & Derrick Appointed Approved Stockist for UK Leading Cable Pulling Equipment Manufacturer

The Cable Run

The LV HV cable run is checked before laying the cable.

Have the minimum bending radii prescribed by the cable manufacturer been followed during laying? If necessary the run must be modified
Are the trench, shaft, cable duct or cable pipe free of foreign bodies, sharp edges or corners and dampness or moisture?

Inspection and examination of the run prior to laying are essential. A visual check, however, is only possible for open trenches or shafts. A brush pulled through the pipe, with monitoring of any potential tension, also permits an assessment of any inaccessible areas.

If the duct brush becomes stuck in the pipe or if there is a temporary but significant increase in tension, this indicates dirty sections or badly fitting pipe connections.

Dolly-mounted cameras can help in the inspection of a pipe or channel. Thanks to modern technology the inside of the pipe can be viewed live on screen. An accompanying meter counter gives the exact position of potential trouble spots.

Cables which are led through shafts or around corners must always run over deflector rolls. This is an effective way to avoid mechanical damage to the cable sheath.

In order to achieve this some corners require a considerable measure of imagination and clever construction. It is therefore essential to have a plentiful supply of deflector rolls and to choose them correctly.

When pulling horizontally rollers should also always be placed on the ground. The cable must not drag along the ground. An even pulling of the cable with the minimum possible resistance ensures quick and faultless laying.

Cables which are led through shafts or around corners must always run over deflector rolls. This is an effective way to avoid mechanical damage to the cable sheath.

Dolly mounted cameras can help in the inspection of a pipe or channel

Cable Pulling Equipment

Cable Pulling & Laying

Installation of Rail Foot Cables

Installation

Further Reading

Cable Pulling Equipment

Installation of Cable Sleeves | Jointing & Splicing Cables

Installation of Cable Sleeves

Further Reading

Cable Pulling Equipment

Cable Pulling | Safe Pulling of Cables Using Manual Laying

Manual Laying

Further Reading

Cable Pulling Equipment

Cable Pulling | Safe Pulling of Cables Using Motorised Pullers

Pulling with motorised assistance

Further Reading

Cable Pulling Equipment

How to Prepare Cables To Avoid Cable Damages & Faults

Preparation of Cable & Run

Further Reading

Cable Pulling Equipment

Cable Pulling & Laying

Installation of Rail Foot Cables

Installation

Further Reading

Cable Pulling Equipment

Installation of Cable Sleeves | Jointing & Splicing Cables

Installation of Cable Sleeves

Further Reading

Cable Pulling Equipment

Cable Pulling | Safe Pulling of Cables Using Manual Laying

Manual Laying

Further Reading

Cable Pulling Equipment

Cable Pulling | Safe Pulling of Cables Using Motorised Pullers

Pulling with motorised assistance

Further Reading

Cable Pulling Equipment

How to Prepare Cables To Avoid Cable Damages & Faults

Preparation of Cable & Run

Further Reading

Cable Pulling Equipment

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