Cape Town – Eskom chief operating officer Jan Oberholzer has warned that load shedding could continue for the rest of the week.
He said Eskom would assess the situation during the course of the day and update consumers accordingly.
The power utility announced earlier today that it would be implementing Stage 2 load shedding from 9am, with outages likely to continue until 11pm.
The City of Cape Town said its "customers will be on Stage 1 from 10:00. Be energy wise and switch off your geyser, pool pump and aircon".
Eskom has blamed Wednesday's power constraints on a broken coal conveyor belt at the Medupi power station in Limpopo, which cut its power output by half.
In addition to the problems at the Medupi power station, five electricity generating units are unavailable due to boiler tube leaks.
Eskom also blamed outages on delays in the return to service of units that were on planned maintenance and said it is struggling with a limited diesel supply.
Oberholzer said the structural damage at Medupi, which would take until the end of the month to repair, had reduced Medupi's output by a third.
Eskom has warned that there is a possibility of load-shedding Stage 2 from 09:00 to 23:00 today.⚠️ Be energy wise and switch off your geyser, pool pump and aircon. For information on the schedule please visit https://t.co/teI8cxSugMpic.twitter.com/PHbmodIMqD
"At this stage we simply do not know what has happened. We do not believe that it is sabotage or old age as the power station and the belts are relatively new," Oberholzer told TimesLive.
"The mechanical teams will have to determine exactly what happened. The problems look as though they were at the pulley systems which saw the belts wrap around the pulleys."
South Africa last experienced load shedding in March this year. Protracted outages could cost the country its last investment-grade credit rating from Moody’s, which will deliver its next assessment on November 1.
Local Government, Environmental Affairs and Development Planning MEC Anton Bredell said: “We are aware of the ongoing pressure Eskom is under, accordingly the Western Cape disaster management centre has made every effort to put contingencies in place to deal with emergency situations where they may occur during episodes of load shedding.
"The number to call in case of emergencies in the Western Cape is 112.”
Bredell has urged the public and businesses to reduce energy consumption as far as possible in order to assist Eskom in stabilising the system as fast as possible.
“Every little thing we turn off could make a difference in reducing demand and eliminating the need for load shedding.”
An Eskom board member warned recently that the power utility's generation fleet was last month as low as 69%, which should be as high as 80%.
It had been predicted that the country would be vulnerable to load shedding from the end of August, when Eskom speeded up its plant maintenance programme.
Eskom board member Nelisiwe Magubane cautioned that an acceleration in economic growth in South Africa could trigger power cuts.
Experts believed that Eskom had succeeded in avoiding load shedding for a couple of months due to a weak economy and that to manage the electricity supply efficiently, it had to ensure its plants are in good shape, regularly maintained and performing well.