Stage 2 load shedding will now be implemented from 08:00 until 22:00 on Saturday and Sunday, Eskom announced on Friday evening.
This will be done to preserve diesel stocks in an attempt to "contain the amount of load shedding", it said.
Eskom added that it was expecting a shipment of diesel supplies to berth on Monday and to offload its cargo on Tuesday.
"If the current burn rate persists, diesel [will] be depleted ahead of the ship offloading," it said in a statement.
"While a single unit at the Duvha Power Station tripped this afternoon, a generating unit each at Tutuka and Medupi power stations have been returned to service. Three generation units are expected to service [on Saturday]. This, however, will not be sufficient to meet the higher demand during the cold front over the weekend.
"We currently have 3 405MW on planned maintenance, while another 15 481MW of capacity is unavailable due to breakdowns."
Power cuts unrelated to load shedding had also been plaguing several suburbs of Johannesburg on Friday.
#Sebenza #OutageUpdate— @CityPowerJhb (@CityPowerJhb) May 20, 2022
We're experiencing an unplanned power interruption affecting the following substations:
Alex, Cydna, Gresswold, Orchards, Observatory, Westfield.
Operators are en-route to site, we'll continue updating customers on developments.
Apologies bahlali ^DR
Eskom appealed to South Africans to help limit the impact of load shedding by reducing the usage of electricity and to switch off all non-essential items.
"Eskom will continue to closely monitor the system, adjust and communicate any changes as may be necessary," the utility said.