Eskom is currently implementing stage 3 load shedding, as there have been further breakdowns at Kusile, Matla and Tutuka power stations.
"Load shedding will be increased to stage 3 from 8am until 10pm on Thursday, after which it will revert to stage 2, as previously communicated," Eskom said.
The power utility noted a slight improvement in generation performance on Wednesday but said load shedding was being implemented because of further breakdowns at its power stations.
"This is in order to continue replenishing the emergency generation reserves, which have been depleted. These emergency reserves are required to respond to emergencies in order to maintain stability of the national grid. Thereafter, stage 2 loadshedding will be implemented," Eskom said.
Breakdowns currently total 13 995MW of capacity, while planned maintenance is 1 273MW of capacity.
"These capacity constraints will continue for the foreseeable future and all South Africans are urged to reduce their use of electricity. Eskom apologises for the inconvenience and uncertainty caused by these interruptions in electricity supply," Eskom said.