Underground Cable Installation Key Activity

Underground Cable Installation Key Activities that should be Followed at Site

Installation of Underground Cables:

Before installation of underground cables in a nice and perfect way it is necessary to consider some points carefully like the excavation of cable trenches, cable laying, cable joint bay and jointing, termination at both ends and back-filling the cable trenches and reinstate the roads, then testing and commissioning for final energizing the cable line.

To ensure the best quality work must engage the qualified personnel who have sufficient knowledge and experience in the construction of underground cable for each part of the work. For dedicated project work, it is important to keep in mind taking appropriate approval from the employer or concern authority before the execution or installation of the cable.

Cable Drum Handling Procedure:

Cable drums shall be unloaded handle and in an approved manner on the hard and well-drained surface so that they must not sink. 

In no case shall the drum store flat i.e. with flange horizontal rolling of drums shall be avoided. For unreeling of cables, the drum shall be mounted on suitable jacks or on wheels. 

All possible care shall be taken during unreeling and laying to avoid dusting twists, kinks or sharp bends.

Cable Bending Radius:

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Cable bending radius is not the same for all sizes and types of cable. 

So keep in mind to follow the bending radii for cables as per the manufacture’s recommendations. 

The cable trench, especially in bending points, should prepare carefully to comply with the manufacturer's instructions and it should be strictly adhered to and a necessary conducting medium shall be provided over the cable outer sheath for checking the healthiness of the outer sheath applied.

Cable Trenches and Cable Joint Bay:

Cable trenches may be constructed for directly buried cables or concrete ready-made trench inside the compound as per employer requirement. 

For cable trench, some key points like road crossing, rail-line crossing, existing power line, communication line or other utilities line crossing should be considered as per international or local standard.  

For direct buried cable trench depth may vary site to site, normally an average depth of 1.5 meters from finished ground level for a typical 132kV underground cable. 

Important for cable trench is sieved sand bedding, riddled soil cover, concrete protective covers backfilling and compacting, route marker and joint marker.

Location of cable joint bay should consider the less traffic, road crossing, water storage, easy access etc.

Cable Laying Formation:

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Cable laying formation may various types, very commonly used formation types are trefoil and flat formation.

 Cable Earthing and Bonding:

Earthling of cable metallic sheath with the cross bonding system and the sheath/screen bonding to the earth through disconnecting type link boxes at straight through joints and both end of cable terminations to avoid any induced voltage is also very important for underground cable system

Finally considerable for the system of cable jointing and termination work should be carryout by experienced joiners who shall have adequate skill and experience in jointing and termination for specified types and voltage grade of cable.