Sep 28, 2015 in direct laying method, the cables with steel tape or wire armouring are laid directly as they afford excellent protection from mechanical injury. The methods used to place fiber optic cables in ducts are similar to those used to place copper cable. The company is an indirect, whollyowned subsidiary of fortis inc. Pdf method statement for excavation and backfilling for. In cable trays or cable ducts fixed with clamps usually at walls and ceilings. The discussion is focused on transmission cables but also has relevance for distribution cable applications. The depth of burial should be enough to prevent damage caused by dragging anchors, which may be in excess of 15 feet for large ships on sandy bottoms. There is a lot of stuff down there already and it would be quite bad news if you dig up, say, a high voltage cable or a gas pipeline.
This method of the laying underground cables is simple and cheap and in much use. Cable laying shall be started by rotating the drum in a direction, recommended and marked side of the cable drum and cables are pulled, accordingly. In a practical situation, there are three main cable laying systems are used commonly for laying these under ground cables which are. There are different methods are used to lay cable in the electrical systems. Insulation resistance of hv cable should be checked by using 5 kv megger after installation and before termination of cables and readings shall be. The overall installation of a cable route over a large distance is broken down into sections of cable that are connected using a cable.
Currently, there are four methods used in laying underground cables. Introduction increasingly, utilities, developers and power producers seeking to build new power transmission systems are required to at least consider underground cables as an alternative to overhead lines. Underground cables april 2018ver2mh the width of the working strip is dependent upon the the voltage of the underground cable, the number of cables and how many trenches are required. The layout arrangement of the draw in the system is shown in the figure. Further, the vertical runs where the cable descends into the ground at the house side and emerges up from the ground at the outbuilding. Indian workers laying an underground cable in south delhi, india. Goal posts bunting and signage erected where necessary. There were followers of this blog asking for mep method statement. Below drawing explain how to lay multiple cables in a single trench. Before laying the different cable sections, all reels should be visually inspected for possible transportation damage. Optical fiber cable pulling in underground horizontal duct routes requires some special. While the crosssection varies between 7 and 15 cm, the depth is typically between 30 and 40 cm. I dont know anything about the digging part of it, other than call digsafe.
Underground cable laying proposal to lay power cable and. Moving forward, we must understand various types of underground cables available to us. Method statement for excavation and backfilling for underground services. This differs from the purpose of chapter 3, which is to correctly install the. High voltage underground cable is supplied in preordered lengths of up 900m on large cable drums. After cable pulling is completed and testing has done, inspection to proceed for cable laying, cable tiles and backfilling. Open trench cable laying is often used as opposed to laying cables directly into cable ducts. An introduction to underground cable installation placing cables underground has traditionally been seen as a more costly solution than an overhead alternative, however lower cost production methods such as xlpe over lead or oil filled cables, improved technologies and installation methods and increased.
The type of installation proposed based on the site conditions and terrain in the project area is underground installation in trenches. The methods of mentions show in below with its unique advantages. Underground power cables high voltage underground cables 2 2 circuits 3000m 3x1x2000mm2 e. Method statement for laying of low voltage cables and wires. Dec 28, 2016 connect the strength member of the cable to the pull line. Unless cables are designed for such use, basket grips and similar methods of attachment should not be used. Optical cable is a high capacity transport medium that is sensitive to excessive pulling force, tight bends, and crushing forces, therefore, proper care must be taken during the. Methods and materials introduction to chapter 3wiring methods and materials chapter 2 provided the general rules for wiring and protection of conductors, and was primarily concerned with the correct sizing of circuits and the means of protecting them. Most extruded cables are ac, but a very few are dc. Telecommunication conduits are made from various materials and buried directly into the soil or encased in concrete. The installation company responsible for laying the cables must heed the following parameters. There are three main methods of laying underground cables viz. All supporting documentation should be read prior to works i. Underground electric transmission lines introduction this overview contains information about electric transmission lines which are installed underground, rather than overhead on poles or towers.
This manual provides installation information for power and control cables for industrial. Method statement for installation of high voltage hv cables. Chapter methods and materials mike holt enterprises. Fiber optic cables have provided a more optimal use of available underground conduit space because of its small cable diameter and the much higher. Lines is more, so the voltage regulation is better in case of underground cables low voltage drop. There are so many parameters to consider while the laying of these cables. Line life insulation deterioration takes place in underground cables much faster because of various loading cycles during their lifetimes as compare to oh conductor which do not have any insulation layering. Method of installation laying of low voltage cable. Putting wires underground involves many essential steps and factors to consider.
Underground installation of optical fiber cable by pulling. Here i am going to explain you about the different methods of laying underground cables. Appendix 3 typical methods of installation of cables. Underground cable installation manual western power. Specification for installation of underground conduit systems. Sep 18, 2011 direct laying draw in system solid system direct laying. Typical cable laying detail for direct buried using duct, low tension cables direct buried method for multiple cables using single cable trench. Underground installation of optic fiber cable placing. As per approved shop drawing warning tape shall be provided 300mm below the ground level along the cable route. Use a swivel while pulling to prevent the cable from being twisted by rigid attachment to a fish tape.
The three most common methods of cable placement are direct buried, cable in conduit, and a total conduit system. Draw in system underground cable laying draw in system cable layout. Methods of cable laying there are various methods of cable lying, such as y laying directly into the ground y drawing in ducts y laying on racks in air y laying on rack inside a cable tunnel y laying along building and structure underground cables ht cables can also be installed in the buried trenches. Power cable installation guide figure f5 multiple sheaves figure f6 sheave arrangements for feeding into cable tray training radius the training radius is the final positioning of cable ends after the cable has been placed in the raceway. Most utilities are currently using one or more of these methods with various degrees of success. Any method used for installing two 240mm2 lv cables in one bore hole needs to be approved by western power. Method statement for installation of high voltage hv. The trench is covered with a layer of fine sand of about 10 cm thickness and the cable is laid over this sand bed. Given a new cable installation task, both the departments have their separate speci. Jan 16, 2015 indian workers laying an underground cable in south delhi, india. Cable laying shall be started by rotating the drum in a direction recommended by manufacturer and as indicated on drums.
Cable shall be tested both before removal from cable drums and onsite with a 1 kv insulation tester 5kv for mv cables. Cables shall be laid on racks or trays strictly in accordance with the laying patterns stated on the layout drawings. This method of laying cables into the ground tends to be used where the cables in use are of a higher voltage mv hv cables and therefore have a greater outside cable diameter. There are three main methods of laying underground cables, which are i direct laying, ii drawin system and iii solid system. The sand bed protects the cable from the moisture from the ground. Direct laying this method is cheap and simple and is most. Insulation resistance of hv cable should be checked by using 5 kv megger after installation and before termination of cables and readings shall be submitted to the consultant. Undergrounding high voltage electricity transmission lines. The classification of underground cables can be done on the basis of several criteria. There are three main methods of laying underground cables a. Technical specification for underground power cables and accessories for nominal system voltages of 66kv and 2 kv page 1 of 24 specificationjts040110 ver 1. Laying of underground cables insulation test single core cable. Then the trench is covered with a 10 cm thick layer of fine sand.
Transmission cables are often 35in 75125mm in diameter and may be installed directly buried or in, typically, 68in 152203mm plastic conduits with commercial installations up to 500kv. Laying uf underground feeder cable directly into the ground. High voltage underground cables i cable cable components 6 conductor 78 inner semiconductor shield 9 xlpe insulation 9 outer semiconductor shield 9 metallic screen 910 outer protective jacket 11 table of cable components 12 metallic screens earthing shortcircuit operating conditions 14 grounding methods 14 earth cable protection 15. Approved code of practice for avoiding underground services and avoid danger from overhead services is adhered to at all times 7. Classification of underground cables the classification of underground cables can be done on the basis of several criteria. Technical specification for underground power cables and. Method 3 9 cables in flush floor trunking method 3 10 singlecore cables in skirting trunking method 3 on trays. This method is normally used for installing heavier electrical cables. Underground cables have different technical requirements than overhead lines and have different environmental impacts. Individual company practices for placing fiber optic cable should supersede any conflicting. Other installations, such as buried and aerial, have different installation parameters. In this method, cable is pulled through ductpipes with the help of preinstalled rope inside the ductpipes.
Now it is time to share with you this method statement. Where the cable crossing is subject to flow or tidal currents, anchors are often used to prevent excessive drifting or shifting of the cable. Normally the cables are layout in ducts or pipelines on the ground with certain manholes. The reliability of underground cable network highly depends upon proper laying of cables, quality of cable joints and branch connections etc. Method 4 7 cables in conduit embedded in masonry, brickwork, concrete, plaster or the like other than thermally insulating materials. In this method, conduit or duct of glazed stone or cast iron or concrete are laid in the ground with manholes at suitable positions. This procedure provides detailed for underground pipe installation in soil conditions as prevalent in the project area. The 3 main underground cable laying system use in practice. Pdf study of high voltage ac underground cable systems. Ul approved lubricant shall be used to assist in pulling fiber optic cable. This method of laying of underground cables is simple and cheap and is much favoured in modern practice.
Underground cables are, of course, meant to be installed or laid under the ground. Protection of the environment during the works laying the 710mm pipe in craigendoran. Cables must be buried in waters where marine traffic is present. Pulling method cable installation into a preinstalled underground ductspipes by manual pulling or by puller machine is called as pulling method. What are the different installation methods for underground. Most construction projects requires underground cabling system for its power. A guideline for laying of cables and installation of sleeves. It is impossible to cover all the various conditions that may arise during an installation. Before pulling the cable, to ensure of the stability of. Here cables run two tier layer and parallel as a matrix system. Cable work shall be done in accordance with sans 10198 and to the satisfaction of the client and the engineer. Spreader bars may be used when multiple support locations are required. In this method, a trench of about 15 metres deep and 45 cm wide is dug.
There are five different methods of laying cables e. Ppt underground cables powerpoint presentation free to. Cable shall be pulled to the cable tray through a rope from cable drum. This is the simplest, cheapest, quickest approach and involves digging up the sidewalk or the first traffic lane, if the sidewalk is too narrow, laying the cables at a soil depth as recommended by standards and restoring the surface. Cables or cable supports shall not be fixed directly or indirectly to plant, equipment or process piping which may require removal or replacement. Direct in the ground in trenches underground cables.
The crosssection and depth of the trench will depend on the number of ducts to be laid. This method of laying underground cables is simple and cheap and is much favoured in modern practice. From the lay down area to the trench site, the pipes shall be transported through trailers. Placing cables underground has traditionally been seen as a more costly solution than an overhead alternative, however lower cost production methods such as xlpe over lead or oil filled cables, improved technologies and installation methods and increased reliability means the cost differential between underground cables and overhead power lines is. We have already seen what underground cables are, and where theyre used. Normally in the electrical system, most of the high voltage cables are laid under the. To overcome these disadvantages, it is necessary to have a uniform stress distribution in cables. This technique has an advantage over conventional cable laying methods in that it is much faster to execute.
The site supervision team will ensure that the stress on pull is not applied to the. This is known as direct burial, and if you do this, the uf cable must be at least 24 inches below the surface of the ground, to minimize the chance of the cable being pierced by routine shoveling. The trench is covered with a layer of fine sand of about 10 cm thickness and the cable. Laying of underground cables the reliability of underground cable network depends to a considerable extent upon proper laying. Coexisting underground utilities if the cable route comes across or is between coexisting underground utilities like sewer line, open drain, canal, bridge and other utility cable trench, the cable. Accurate and faultless installation and assembly of cables. Specification for installation of underground conduit systems revision date.
Sheathed multicore cables in free air distance between wall and cable surface not less than 0. Types of cables are classified in different ways on the basis of their. Method statement for optical fiber cable installation project. The reliability of underground cable network depends to a considerable extent upon the proper laying and attachment of fittings i. In addition to laying cables directly on the bottom, burying cable in a trench using the jetwater method should be considered. The korean electric power research institute kepri performs economic evaluations and modeling to select the best real distribution line option. Temperature range the temperature range of the cable is of great importance for both the user and fitter. Various aspects are taken into account while classification and these include. A typical cable length on one drum would be in the order of 600m750m. Erect all necessary signage to serve notification that construction work, particularly excavation work is in progress in accordance with chapter 8 10.
In many countries around the world, electrical cables are laid underground for aesthetic and safety purposes. There are three main methods of laying underground cables, which are i direct laying, ii drawin system and iii. Underground cable and ducts are part of the underground conduit system. Clarified cable sealing, exposed cables and terminated cables requirements, section 14. The following are the two main methods of grading of cables. Power cable installation guide cables installed into conduits or trays have installation parameters such as maximum pulling tensions, sidewall pressure, clearance, and jamming, which must be considered. It may be increased at certain points, for example road, rail, river and canal crossings, to accommodate the more complex construction processes at these locations. However, fiber optic cable is a high capacity transmission medium which can have its transmission characteristics degraded when subjected to excessive pulling force, sharp bends, and crushing forces. Then the laid cable is again covered with a layer of. Installing electricity cables is a vital step in engineering and development. Technically a possibility exists to operate both cables in one trench but no provisions could be found for laying the power cable and the communication cable together.
For long distance power transmission, the charging current. How to do a sweep search to locate underground cables and. As an example, traditional methods of thermal endurance characterization for xlpe insulated power cables are all based on analytical toolsinfrared carbonyl absorbance, melting point, differential. The methods for the underground installation of cables can be categorized as opencut and nodig. One of these is concerned with the laying of the physical network of wires or cables. Cables placement will take place mainly above ground in perforated, laddertype cable trays. These limits should not be used for cables subjected to pulling tensions during installation. When cables or raceways are run underground, they must have a minimum cover in accordance with table 300.
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