The power outages would be from 8am until 10pm, it said in a statement.
“This is due to a shortage of generation capacity as several units are currently on unplanned outages due to technical faults,” Eskom said.
“Furthermore, units that were expected to come back on line after maintenance have delayed and among them Koeberg’s Unit one.”
On Monday, Eskom said the power grid was under pressure after one of Koeberg’s 900MW units was taken out of service because of a technical fault.
“The unit is expected to be at full capacity by the end of the week. The same unit is due for planned outage on 9 February 2015 and will be returned to service again in May,” the power utility said at the time.
Spokesman Khulu Phasiwe confirmed a report on Friday that the unit went offline due to the incorrect positioning of scaffolding in preparation for maintenance.
The scaffolding accidentally touched an electrical point, causing a trip.
“The unit itself was not affected. It was not inside the nuclear side, but outside,” he said.
“The safety and integrity of the nuclear reactor was not affected.”
Stage three power cuts were implemented on Thursday from 4pm to around 11pm.
Stage one allows for up to 1000MW of the national load to be cut, stage two for up to 2000MW, and stage three for up to 4000MW.