Eskom began implementing stage one load shedding at 4 o'clock on Monday afternoon due to a shortage of capacity.
The outage will last until ten o'clock.
The power utility's Khulu Phasiwe said the system is extremely constrained at the moment.
In what is becoming virtually a daily occurance - Eskom ended stage two rolling power cuts at ten o'clock on Sunday night.
It warned that the power system would be under severe pressure over the coming week.