Stage 2 load-shedding will be implemented from 10am on Wednesday morning until 10pm on Friday night.
This follows further breakdowns of generating units at Arnot and Majuba power stations.
Eskom says emergency generation reserves have been depleted due in the past few days while trying to avoid load-shedding during the day.
The power utility is pleading with the public to use electricity sparingly, as its systems are under severe constraint.
These constraints will persist throughout the high winter demand period.