The struggling state-owned company resumed power cuts on Wednesday after a pause of 11 days, and implemented them again on Thursday and Friday.
Last month weeks of regular outages prompted public anger and prompted President Cyril Ramaphosa to make new pledges to tackle the crisis.
Eskom's power station fleet comprises mainly of coal plants that are highly prone to faults.
A record amount of electricity is set to be cut from the national grid this year, constraining economic growth in Africa's most industrialised nation.
Stage 2 outages require up to 2,000 megawatts to be shed from the grid.
(Reporting by Bhargav Acharya in Bengaluru; Editing by Alexander Winning)
