Requirements of the Cables

          An underground cable can be defined as the group of individually insulated one or more conductors which is put together and finally provided with number of layers of insulations to give proper mechanical support.

       The conductors used in the cables are usually aluminium or annealed copper while the insulation is commonly PVC or other chemical compositions. Many types of cables are available depending upon the nature of conductors, number of conductors, types of insulation used etc. The basic necessary requirements of the cables are,

 

1- The size of the conductors used must be such that it should be carry the specified load without overheating and keeping the voltage drop well within the permissible limits.

 

2- As the voltage level for which cables are designed, the insulation thickness must be proper so as to provide high degree of safety and the reliability.

 

3- The cables must be surrounded by number of layers of an additional insulation so as to give proper mechanical strength and protection. Thus the cables can withstand the rough use at the time of laying them.

 

4- The material used in the manufacturing of cables must be such that there is complete chemical and physical stability throughout.