Johannesburg - Power cuts are scheduled to take place throughout the weekend, Eskom said on Friday afternoon.
"Load shedding will recommence again tomorrow [Saturday] and Sunday at 21:00 in order to build up reserves for the week ahead," it said in a statement.
It said there were a number of reasons for the cuts that began on Friday afternoon.
"The power system is extremely constrained... due to unforeseen technical problems at power stations, depleted water reserves at our peaking power stations, which use water to generate electricity, and depleted diesel reserves to fire up the open-cycle gas turbines."
Load-shedding schedules were available to Eskom's direct customers on its website. Customers could also contact their call centre for additional information.
Earlier this month, a coal storage silo at the Majuba power station in Mpumalanga collapsed, resulting in widespread power cuts. The silo held more than 10 000 tons of coal and affected coal supplies to all six units at the power station.
An investigation is under way.
Meanwhile, Democratic Alliance MP Natasha Michael said in a statement that she had heard reports on Friday that there was "another cracked coal silo at Majuba".
She said the party was concerned about what was really going on at Eskom.
"... There is no information publicly available that sheds light on what is really happening at Eskom," she said.
Michael said the DA would institute a Promotion of Access to Information Act application to compel the public enterprises department to release information on the matter.