Stage 3 load shedding will be implemented from 18:00 on Tuesday, Eskom said.
"Due to the vulnerable system, stage 3 load shedding will be implemented from 18:00 to 22:00," Eskom announced on Twitter.
Visit News24's GridWatch (http://loadshedding.news24.com/) to see how this will affect you.
Big industry players will also cut 10% of usage from their operations.
On Tuesday, Eskom said the electricity supply system remains very vulnerable due to a shortage of generation capacity as several units are currently out of service due to planned and unplanned outages.
Eskom said it would like to assure customers that load shedding is implemented as a necessary measure to protect the power system.
"Any additional changes on the already vulnerable and constrained power system could lead to a change in the stage of load shedding at short notice. We will communicate if there is a need to change stages."
Source: Fin24