The affected areas were Eco Park and nearby office blocks, the Tshwane vehicle testing and licensing centre, and Heritage Hill, spokesman Lindela Mashigo said.
“The outage was caused by acts of attempted theft and vandalism of electrical cables that caused panels to burn at the Nivs substation.”
Technicians were working on restoring the power and estimated it would be done by midnight.
Mashigo urged power users to switch off all non-essential appliances to ease the load on the electrical network.
“The city apologises for the inconvenience caused to the affected residents.”