City Power said its immediate focus on Monday, would be to clean the affected infrastructure, replace stolen equipment and carry out the necessary tests to establish which parts of the network can be restored.
This follows a third fire at the central substation on Saturday early morning.
The local power utility confirmed a suspect is under police guard at a hospital, where he is treated for burnt wounds.
Moreover, technical teams found evidence of vandalism, when they discovered an axe, a jigsaw, and other tools commonly associated with cable theft, most of which were found beneath the damaged equipment. There was also evidence of attempts to cut copper cables in the area. Preliminary observations suggested that the suspected tampering may have triggered the explosion and subsequent fire.
But City Power cannot provide an estimated restoration time, as teams must first complete the necessary cleaning, checks and restoration work.
The most affected customers are in Marshalltown and surrounding parts of the Johannesburg CBD.
Charles Tlouane, Acting CEO of City Power, said a team on site at the substation would work on a restoration and repairs plan.
Picture: Charles Tlouane, Acting CEO of City Power, briefing community leaders outside the Central Substation.