Power utility Eskom would implement stage two rolling blackouts from 14:00 on Wednesday, it stated on Twitter.

"Loadshedding will move into stage 2 from 14:00. This is as a result of power station units not returning to service as planned," Eskom tweeted.

Earlier, Eskom said unit 3 at Majuba power station had an ash conveyer belt which was stuck and at Duvha, unit 2 tripped on Tuesday night due to a technical fault.

Work continued at Koeberg which experienced a fault on Sunday.

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.

Stage one blackouts were implemented on Wednesday between 10:00 and 22:00.

Stage one allows for up to 1 000 MW of the national load to be cut, stage two for up to 2 000 MW, and stage three for up to 4 000 MW.