"Engineers are still inside the station working on fixing the problem. It is labour intensive work that will take time," said Ekurhuleni metro spokesman Themba Gadebe.
Affected areas include Aston Manor, Nimrod Park, Bonaero Park, and parts of Pomona and Glen Marais.
The explosion occurred at Aston Manor substation at around 2am on Friday.
The cause of the explosion was not yet known, Gadebe said.
The Breakfast with Martin Bester team has decided that they, like most S...Breakfast with Martin Bester 1 day, 14 hours ago
Join Jacaranda FM's Drive with Rob and Roz for the ultimate holiday in p...The Drive with Rob & Roz 1 month ago