Johannesburg - Eskom said it will rework maintenance plans on South African power plants to ensure the state-owned utility has enough electricity supply to meet demand after a boiler incident cut 600 megawatts of capacity.

Excess pressure in a boiler at the Duvha coal-fired plant in the Mpumalanga province caused the facility’s third unit to trip on March 30, the Johannesburg-based company said in an e-mailed statement yesterday.

Duvha has six units, each with the capacity to generate 600 megawatts.

An investigating team of engineers was unable to start its probe yesterday because they had to wait for the boiler to cool down, Andrew Etzinger, a spokesman for the company that provides more than 95 percent of South Africa’s electricity, said today.

“We will rebalance maintenance on our other power stations to ensure supply,” Etzinger said by phone.

“While the system is very tight we are not predicting any load-shedding,” he said, using the local term for rolling blackouts.

More information about the damage and when the unit will return to service will be made available as the investigation proceeds, he said.

Eskom started rolling blackouts for the first time in six years last month, shutting shops and factories, after it declared an emergency because of heavy rains that disrupted coal supplies.

The company is spending 500 billion rand through 2017 adding almost 11,000 megawatts of capacity to the national grid and servicing its aging fleet of plants.

About 25 percent of Eskom’s 42,500 megawatts of installed capacity has been out of service this year, according to Bloomberg calculations made using the company’s data.

One megawatt is enough to power about 200 middle-income South African homes at peak times, Etzinger said on March 7. - Bloomberg News