Stage 2 power cuts will start at 9am on Tuesday and continue until Saturday, Eskom said.
The power utility said that this was due to a shortage of generation capacity.
Eskom said that while it had managed to return a unit at each of its Kusile, Matimba and Arnot power stations on Tuesday morning, further delays in returning other units to service had exacerbated the capacity constraints.
This was affecting the utility’s ability to replenish the emergency generation reserves.
Eskom’s spokesperson Sikonathi Mantshantsha: “Eskom anticipates to return Koeberg unit one to service at the weekend. Eskom also expects to return five nits to service during this week. However, there are a number of generation units running at risk of failure that cannot be attended to at this moment due to the current capacity constraints.”