A fault at the Duvha power station near Witbank in Mpumalanga, which put all four of its generating units out of action, has contributed to a return of load shedding - for the first time since 22 February.
Stage 1 load shedding will continue until 23:00 on Monday evening. Load shedding is expected until Thursday this week.
Eskom spokesperson Sikonathi Mantshantsha told Fin24 on Monday morning that the utility faced several challenges at four power stations over the weekend.
The biggest was at Duvha where an electrical fault tripped four units at once. An electric board, which was undergoing regular maintenance, as well as the back-up board tripped.
Mantshantsha told Fin24 that the main board was ultimately fixed, but can only be restored to full function gradually.
He said Tutuka power station, near Standerton in Mpumalanga, has also been erratic, due to its ageing components. Boiler tube leaks hit the power station over the weekend.
Mantshantsha said ageing infrastructure would continue to be a problem for Eskom, and would exacerbate the risk of load shedding for some time.
More than 80% of Eskom's power stations are older than 40 years. The oldest power station - Hendrina, in Mpumalanga - is 55 years old. Only two or three of Eskom's power stations were completed in the past five years.
He said the ageing machinery at some stations was unreliable and unpredictable. As such, he concluded, South Africans must expect that they will have these problems that will lead to bouts of load shedding, often on short notice.
The article has been corrected to replace references to the Majuba power station.