Eskom will implement stage 4 load shedding from 11am on Friday until midnight, and again on Saturday and Sunday from 5am until midnight, amid ongoing unprotected labour action, it said in a statement on Friday.
"It is necessary to bolster emergency generation reserves to react to unforeseen circumstances, as well as to replenish emergency reserves to prepare for the week ahead," spokesperson Sikonathi Mantshantsha said.
"This would help fill the generation deficit while dealing with generating units that may trip amidst the disturbances and compensate for the inability to return generating units timeously to service.
"While exploring possible solutions to unlock the deadlock with the unions, Eskom appeals to its labour partners and striking employees to embrace the higher purpose of putting the people of South Africa first, respect the law and to desist from illegal and undemocratic conduct."
Eskom also warned that there would be a high risk of load shedding in the coming weeks. A total of 2 766MW is on planned maintenance, while another 17 395MW of capacity is unavailable due to breakdowns.
Fin24 previously reported that a deadlock had been reached with National Union of Metalworkers of SA during wage negotiations at the Central Bargaining Forum on Thursday.
In May, Numsa demanded a 15% wage increase across the board, which Eskom management maintained it could not afford. As a breakdown of talks remained a looming possibility, Eskom CEO André de Ruyter told reporters at the time that Eskom did not expect an unprotected strike at the entity over a wage talks deadlock.
Numsa maintained that workers' wages would not negatively affect Eskom's balance sheet, as wage costs remained flat between R16.9 billion and R17.4 billion, "at most increasing by 2.3%". It said it would consult with workers on the way forward.
On Thursday, protests following the deadlock blocked access to some of the power stations, blocking the movement of people and goods.