City Power said it is satisfied with some equipment in one section of the burnt central substation, at the Johannesburg city centre.
This follows testing, which is already underway, simultaneously with the cleaning exercise.
The substation caught fire for the third time in just two months, on Saturday.
But City Power cannot at this stage confirm restoration, because repairs of damaged cables continue.
Once the repairs are completed, the cables will be tested and, subject to satisfactory results, City Power will attempt to restore electricity supply to affected customers.
Charles Tlouane, Acting Chief Executive Officer of City Power, said the restoration process is coming in stages.
First the cleaning, repair and testing of burnt infrastructure before it is returned to service.
“This is necessary to ensure that the network is safe and stable before electricity supply is restored” he said.
Investigators also found evidence of tampering with infrastructure at the substation, including an axe, a jigsaw and other equipment associated with cable theft, as well as evidence that copper cables had been cut.
Picture: Supplied