Msunduzi Municipality is having to source a new 11kv circuit breaker for the sub-station near Meadow Feeds in Pietermaritzburg.
Large parts of city were plunged into darkness on Wednesday night following an explosion at the facility in Ohrtmann Road.
Staff at the electricity department say the damage caused to the breaker, when it blew up, means a new one will need to be found. It will be installed during the course of Thursday.
The sub-station is currently running on generators.
Wednesday night’s power failure affected Riverside, Woodburn, Hesketh, Mkondeni, Panorama, Bishopstowe and Willowton.
The cause of the explosion is not known.