Eskom announced on Tuesday that it would be implementing stage 2 load shedding, starting at 22:00 and ending on Wednesday morning at 05:00.
This cuts are expected to continue again on Wednesday night into Thursday morning.
The embattled power utility said the cuts were necessary to "preserve emergency generation reserves in preparation for higher demand expected during January as economic activity resumes".
The utility currently has 9 745MW out on planned maintenance, and another 11 346 MW capacity unavailable because of unplanned maintenance.
"Eskom will communicate timeously should there be any significant changes to the power system," it said.