Cape Town - Eskom has confirmed that it will implement Stage 2 loadshedding between 9pm on Thursday and 6am on Friday due to "system contraints" and "depleting emergency resources".
Eskom added the risk of loadshedding remains for tomorrow into the weekend.
"We have been using pumped storage schemes and open cycle gas turbines extensively over the past few days in order to supplement capacity, and we need to replenish these overnight," said the power utility in a statement.
Eskom said unplanned outages were reduced at 12 683MW at 13:30 on Thursday afternoon.
Opposition party Democratic Alliance said Eskom's warning that South Africa will experience load-shedding on Thursday evening was a clear sign that the power utility could not be saved.
"Eskom's warning today of a heightened risk of blackouts this evening again shows that it is in a death spiral and that it is time for the ANC government to get out of the electricity generation business and give the power to generate electricity to the people," DA public enterprises spokesman Ghaleb Cachalia.
The power utility has once again urged South Africans to use electricity sparingly.