Eskom says it will continue implementing stage 4 load-shedding until 11pm on Tuesday, when it will drop to stage 2 - before it is ramped up to stage 4 again.

From 11pm on Tuesday, stage 4 rotational powercuts will be downgraded to stage 2. But from 9am on Wednesday - when the low-usage period is done - it will be back to stage 4.

This, the power utility said, was due to a shortage of generation capacity resulting from unplanned breakdowns, including Koeberg Unit 1.

"The loss of the approximately 930MW in Koeberg puts further strain on the generation fleet, necessitating an increase in the stage of load-shedding. Unplanned breakdowns or outages were at 12,046MW as at 5.50pm and planned maintenance outages are at 6,155MW."

Koeberg Unit 1 was disconnected from the grid due to a fault on the turbine section earlier today. The nuclear reactor remains safe, said Eskom.

Repairs to a damaged seawater circulating water pump could take a number of days to repair, before the unit can be brought back online.