Eskom has started to implement Stage 2 load shedding - up from the initial Stage 1 load shedding announced earlier in the day.
In a tweet on Thursday, the power utility said it will implement up to Stage 2 load shedding as a result of a shortage of capacity.
Stage 2 load shedding is expected to continue until 11pm.
Eskom customers can also contact the customer contact centre at 0860 037 566.
Load shedding is conducted rotationally as a measure of last resort to protect the power system from a total collapse or blackout.
Source: South African Government News Agency