Johannesburg - Eskom customers can expect power cuts on Wednesday night and Thursday night, the power utility said on Tuesday morning.
The parastatal warned that the electricity grid was under huge pressure and there was a good possibility of load shedding during peak hours.
Eskom spokesman Andrew Etzinger said when the power system was constrained, any extra loads or faults in the system were likely to result in load shedding.
The most likely times for this to happen is during peak times, between 5 and 9pm.
Last week on the same days, Wednesday and Thursday, the power utility was also forced to load shed during these times.
Etzinger said it could not be reliably predicted whether, and in which areas, the power cuts would happen.
“We make the decision as we see the consumption rising in specific areas of high consumption,” he said.
Eskom calls on consumers to urgently switch off electrical heaters, geysers, pool pumps and all non-essential appliances.
It requires voluntary savings of at least 10 percent in order to manage demand.
Commercial customers, particularly shopping centres and office blocks, can make a big difference by switching off non-essential lights and not leaving office equipment in standby mode after hours.
Eskom, Etzinger said, was taking all necessary steps available to keep the lights on, but it required partnership with customers to ensure that electricity usage was reduced. “We will utilise all necessary emergency resources at (our) disposal, but should the demand not decrease, load shedding will be implemented as a last resort to protect the national grid from a total shutdown,” he said.
Joburg residents using electricity from City Power will not be affected.
Earlier this week City Power spokesman, Louis Pieterse, said there would be no load shedding on condition that residents and businesses continued to use power sparingly as they had done over the past few months.
The power utility has done a lot of planning since 2008 installing thousands of ripple relays, which are remotely controlled devices which can switch off power to properties to save electricity, which had eased pressure on the system.
City Power also had spare power from its Kelvin power station, which was sold to Eskom, but which it could, by agreement, use for the city if it ran short and which would allow for an additional 140kW of power for the city, Pieterse said.
Pieterse said City Power had, in total, about 200mW in reserve.
He stressed that it was not yet full winter, so Joburgers may soon start using more power and cautioned that load shedding could still happen.
So far key customers and the residents of Joburg had co-operated in preventing load shedding, he said.
Speaking on the numerous outages around the city in the past few weeks, Pieterse said these were a result of theft, not load shedding.
Some 37 percent of outages were due to copper theft, he said.
Overloading from areas which were overcrowded was also contributing to power outages, he said.
Residents can check on the Eskom website whether they are due for load shedding on loadshedding.eskom.co.za.
Customers can also contact the customer call centre at 0860 037 566.
The system is expected to remain tight into next week, especially between the peak times of 5pm and 9pm when the demand increases due to residential usage in the evenings.