Section 66(2) in The Indian Electricity Rules, 1956
(2)Nothing in the provisions of sub-rule (1) shall preclude the employment in generating stations, sub-stations and switch-stations (including outdoor sub-stations and outdoor switch-stations) of conductors for use at high or extra-high voltages which are not enclosed in metal sheathing or preclude the use of electric supply-lines laid before the prescribed date to which the provisions of these rules apply.
