Eskom Acting Group Chief Executive Officer Jabu Mabuza says the decision to implement load shedding was taken only as a last resort.
Mabuza was speaking at a media briefing at OR Tambo International Airport on Thursday evening where he took the country into his confidence to explain the circumstances that led to the power cuts.
"The decision to implement load shedding was taken as last resort. It was one we needed to take to balance supply and demand. We understand the impact that comes with load shedding on consumers and the economy," he said.
The briefing by the Eskom leadership followed two days of rotational load shedding.
On Wednesday morning, the power utility announced that due to a loss of additional generation, delays in the return to service of units that are on planned maintenance and limited diesel supply, it became necessary to implement Stage 2 rotational load shedding in order to protect the power system from a total collapse.
Thursday saw Eskom continue to implement load shedding from 9am to 11pm to assist the constrained electricity supply.
On Friday, Eskom will be implementing Stage 1 load shedding.
Highlighting some of the issues that led to the power cuts, Mabuza said a broken conveyor belt at Medupi used to transport coal to the plant, a failure on six boiler tubes coupled with planned maintenance were among some of the challenges.
"Contingency measures were put in place to manually feed coal to Medupi while we endeavour to fix their conveyor belt. We have made considerable progress in that we now expect this to be done by the middle of next week," Mabuza said.
In September, Eskom announced its summer plan in which it did not foresee any load shedding over this period if it could contain its unplanned outages below 9 500MW.
But it became necessary due to the high levels of consumption over the past weekend and breakdowns that exceeded the 10 500MW level which led to excessive utilisation of its water and diesel emergency reserves.
At the weekend, six power stations were shut down due to power leaks, which in turn contributed to unplanned outages increasing to 12 000MW.
Mabuza explained that the summer period provided its own challenges such as air temperature and wind direction which, in turn, had a negative impact on the efficiency of the coal-fired plants.
"The summer period is different to winter in that the profile of demand is such that it peaks in the morning and remains relatively flat during the day and peaks again in the evening. Although the demand is flat during the day, it is relatively higher compared to winter," Mabuza said.
He also emphasised that Eskom decided to use up all their emergency reserves to keep the power on, this would have left the power utility in a worse off position than before.