Electric power can be transmitted (or) distributed either by over-head lines system or by underground cable system . The underground cable system have several advantage, such Advantage :-  • Less chance to damage through storms or lightning. • Low maintenance cost. • Less chances of fault. • Not affected by man- made problems like sabotage , strike etc. • Voltage regulation in UG cables system is much  better, because they have less inductive losses . • Better general appearance of area compared to O.H lines. Disadvantages :- However, their major draw back / disadvantages are • Initial cost of UG cable system is heavy. • • The cost of joints are more. • Introduce insulation problems at high voltages • compared with O.H lines. UG cables are employed where it is impracticable to use O.H lines like  (i) thickly populated areas, where municipal authorities prohibit O.H lines for the reason of safety. (ii) Around plants (iii) In Substations, (iv) Where maintenan...