An underground cable essentially consists of one or more conductors covered with suitable insulation and surrounded by a protecting cover.Although several types of cables are available, the type of cable to be used will depend upon the working voltage and service requirements. In general, a cable must fulfil the following necessary requirements :
The conductor used in cables should be tinned stranded copper or aluminium of high conductivity. Stranding is done so that conductor may become flexible and carry more current.
The conductor size should be such that the cable carries the desired load current without overheating and causes voltage drop within permissible limits.
The cable must have proper thickness of insulation in order to give high degree of safety and reliability at the voltage for which it is designed.
The cable must be provided with suitable mechanical protection so that it may withstand the rough use in laying it.
The materials used in the manufacture of cables should be such that there is complete chemical and physical stability throughout.
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