20 Questions
What is the recommended order for placing cables of different categories in the same trench?
Telecommunication cable, signalling cable, power cable
Why should signalling cables for outdoor circuits not be laid above ground?
To avoid mechanical damage to the cable
What is the minimum depth required for laying tail cables?
0.50 meters
What is the purpose of spacing cable supports in outdoor circuits?
To avoid sagging of the cable
How should indoor signalling cables be laid?
On ladders, channels or in any other approved manner
In which type of area can cables be laid at a depth of 1.2 meters?
Theft prone areas
What should be done when laying cables between the tracks?
Carry the cables in trunking/duct/pipe kept sufficiently below the ballast level
What is the purpose of using ducts while laying cables?
To protect the cable from damage
What is the minimum separation required between signalling cables and HT power cables?
3 meters
What is the recommended minimum distance from the centre of the nearest track for laying cables outside the station section?
5.5 meters
What is the purpose of using a row of bricks or other approved means to separate signalling cables from LT power cables?
To reduce the electromagnetic interference between cables
What should be done at each end of the main cable?
Keep an extra loop length of 6 to 8 meters
What should be done after laying the cables?
Back fill the trenches properly
In which type of pipe can cables be laid?
Half Cut DWC-HDPE pipe/RCC
What type of cable joints should be used?
Approved type
Why is it necessary to maintain a distance of approximately 10 cm between cables of other departments and signalling cables?
To prevent damage to the cables
What should be avoided when laying cables in a Cable room/Relay room?
Sharp cable bends
What is the main purpose of laying cables in a trench?
To protect the cable from damage
What is the recommended depth for laying the main cable parallel to the track?
1.0 meters
What is the purpose of using a joint circular issued by the Civil Engineering, Signalling and Electrical Department?
To provide special precautions for laying cables in station yards
Study Notes
Cable Laying Instructions
- Cables shall be laid generally as per instructions given in this chapter, with special precautions taken in station yards where multiple utilities may exist.
- Cables may be laid underground, either in trenches, ducts, cement troughs, pipes, or any other approved manner.
Cable Depth and Protection
- Main cables laid parallel to the track shall normally be buried at a depth of 1.0 meters from top of cables to ground level, including those laid across the track.
- The depth shall not be less than 0.50 meters for tail cables.
- In theft prone areas, cables may be laid at a depth of 1.2 meters with anchoring at every 10 meters.
- Half Cut DWC-HDPE pipe/RCC or any other approved type of ducts/pipes shall be used to protect the cables.
- Ducts shall be designed and lengthened to prevent/minimize damages to cables by future digging activities in the vicinity.
Cable Separation and Arrangement
- Cables belonging to other departments must not be laid in the same trench along with Signal & Telecommunication cables.
- A distance of approximately 10 cm must be maintained between cables of other departments and signalling cables.
- Signalling cables must be separated from LT power cables by a row of bricks or any other approved means and from HT power cables by a minimum of 3 meters.
Cable Laying Order and Precautions
- Where several cables of different categories have to be laid in the same trench, they shall be placed in the following order, starting from the main track side:
- Telecommunication cable
- Signalling cable
- Power cable
- Signalling cables for outdoor circuits should not normally be laid above ground, but if necessary, precautions should be taken to avoid mechanical damage.
Indoor and Outdoor Cable Laying
- Indoor signalling cables should normally be laid on ladders, channels or in any other approved manner, neatly tied/laced.
- Outdoor cables shall be laid in ducts suitably protected, and in station yards, cables shall be laid in ducts suitably protected.
This chapter discusses the guidelines and precautions for laying cables in railway stations, including underground cable laying methods. It also mentions the importance of joint circulars from relevant departments.
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