Lights were not restored until Thursday morning in some parts.
On Twitter Joburg City Power said it had restored power, but most areas which were affected remained in the dark.
“Several of our substations controlled from the Eskom side were since the afternoon delayed to be restored, sending panic to our customers.
“They include Randburg substation, which feeds Bromhof, North Riding and Randpark Ridge, which was scheduled to return late afternoon and Bryanston Fontainebleau, North Riding, Beyers Naudé, Harley, Windsor and Morningside substations scheduled for restoration at 8pm.
“We are working with Eskom to address the delays and restoration and appeal to our customers to bear with us.
“We apologise for the inconvenience caused to the customers,” he said.