The "Stage 6" power cuts, the worst outage level on record, require up to 6,000 megawatts to be shed from the national grid, and mean up to 10 hours a day without power for some South Africans.
Further changes on the stages of load-shedding at short notice are possible given the high number of breakdowns, Eskom said in a statement.
Eskom has been implementing the worst rolling blackouts in South Africa on record, leaving households in the dark, disrupting manufacturing and hurting businesses of all sizes, leading to President Cyril Ramaphosa declaring a national "state of disaster" earlier this month over his country's crippling power shortages.
South Africa's power problems have been reflected in its economic health. Several key indices have fallen in recent months, which analysts attribute in good part to the lack of electricity to keep businesses going.