Almost all power that was lost in Johannesburg on Thursday has been restored.
City Power spokesperson Louis Pieterse said 85% of electricity was restored by 11am.
The only areas left without power were Observatory and Alexandra.
”Those areas should have full supply by midday,” Pieterse said.
A major substation located in Prospect near City Deep tripped on Thursday morning, causing various other smaller substations which it supplies, to lose power.
”The trip caused a ‘downstream effect’ as the Prospect substation imports electricity from Eskom,” he said.
About 30 areas were left without power in the central business district, the south and north-eastern suburbs, including Gresswold, Kensington, Bellevue, Mondeor, Glenvista, Rosettenville and Booysens.
Traffic lights were also affected in the Johannesburg CBD, causing major disruptions to people travelling to work.
Bree, Sauer and Rissik streets were among those affected, as well as Houghton, Parktown, Orange Grove and most of the inner city.
Pieterse said an investigation into what caused the substation to trip, would be conducted.
”It could have been caused by theft or vandalism — which would interfere or damage circuits, or there could be a transmission line problem,” he said. — Sapa