Power utility Eskom says the recent inclement weather conditions have resulted in a number of outages in the Gauteng and Eastern Cape provinces.
Storms and heavy rains began in Gauteng on Thursday night, and widespread thundershowers are forecast to continue throughout Friday.
Eskom said this resulted in “a high volume of network faults across Gauteng”.
In the Eastern Cape, Eskom said the most affected customers resided in the Amathole, Chris Hani, Joe Gqabi and OR Tambo districts.
Partly cloudy weather conditions are expected in the Eastern Cape on Friday.
Eskom assured they were attending to the current faults, and appealed for patience while they worked on restoring supply.
Stage 2 load shedding was implemented on Thursday afternoon, and is scheduled to run from 9pm to 5am on Friday and Saturday as well.
This was the first time since 22 July that load shedding had to be implemented.
Eskom explained in a statement this was due to emergency reserves depleting “faster than expected”, owed to breakdowns of a generating unit at Kriel and Tutuka power stations on Thursday.
There were also delays in returning units to generation at Tutuka, Grootvlei and Kendal.
On Thursday, Eskom spokesperson Sikonathi Mantshantsha said should emergency reserves not recover sufficiently, load shedding could continue into the weekend.
Residents have been urged to use electricity as sparingly as possible.