Eskom has announced that South Africans will face a full day of Stage 4 load shedding on Monday as it battles a shortage of capacity.
The power utility implemented Stage 4 load shedding on Sunday. It said rotational power cuts would continue throughout the night at Stage 2 level until 09:00 on Monday, when Stage 4 will again be implemented. Power cuts during the nights have thus far been rare.
Stage 4 load shedding allows for up to 4000 MW to be shed from the national grid. The power utility said that load shedding - up to Stage 4 - might also be implemented on Tuesday.
In an alert on Sunday evening the utility said the power rationing is "no cause for alarm as the system is being effectively controlled".
"Eskom's maintenance teams are working round the clock to return generation units to the electricity system," it said.
The utility did not detail on Sunday what exactly caused the shortage of capacity.
President Cyril Ramaphosa, in a statement on Sunday, said that some of the electricity shortfall had been caused by storm damage to the Mozambican transmission line to SA from the Cahora Bassa hydroelectric generation station.
"The loss of the the supply from Cahora Bassa has contributed to the implementation of Stage 4 load shedding, which is the level at which the power utility tries to pre-empt a national blackout," said Ramaphosa.
He said the SA National Defence Force on Sunday provided airborne support to Eskom technicians conducting aerial surveillance of damaged power lines in Mozambique.
"The SANDF is also on standby to assist Eskom to transport any equipment that may be required to repair damaged infrastructure on an emergency basis," he said.