File image by Keith Galens

Johannesburg - At least four cities across the country were contending with power cuts on Sunday after a coal silo collapsed at Eskom's Majuba power station in Mpumalanga.

Johannesburg, Pretoria, Cape Town and Port Elizabeth have been warned of rolling blackouts after Eskom lost 1800MW when the silo cracked and collapsed.

The outages could last the rest of the week, Eskom warned.

Pretoria was asked to reduce its electricity consumption by 280MW.

"Tshwane will be on rotational load shedding for the rest of the day," it said in a statement.

The rotation would continue until 10pm.

The silo, which stores over 10,000 tons of coal, cracked on Saturday afternoon, affecting coal supplies to all six units at the power station.

It collapsed on Sunday, damaging the conveyer belt systems, which fed coal to the power station, Eskom spokesman Andrew Etzinger said. Before the collapse Majuba supplied 3600MW, roughly 10 percent of the country's electricity capacity.

Johannesburg, Cape Town and Port Elizabeth had also begun power cuts on Sunday.

The Nelson Mandela Bay municipality in the Eastern Cape said it would cut power to areas for two hours at a time, according to its load-shedding schedule.

Johannesburg's power utility, City Power had been asked to cut back on 460MW, it said in a statement.

The Ekurhuleni municipality said it had been switching customers off since 8.30am, according to the schedules on its website.

The City of Cape Town received a similar request from the national power utility.

"Residents and suburbs may be affected at their indicated times, depending on the current demand from Eskom," it said.

The Democratic Alliance claimed poor maintenance and a lack of quality control caused the crack in the silo.

"This is a direct result of Eskom's deficient maintenance and planning and the public enterprise ministry's lack of quality control measures over Eskom," DA MP Natasha Michael said in a statement.

Michael intended writing to Public Enterprises Minister Lynne Brown to ask for a detailed timeline for maintenance on all the country's power stations, to avoid such failures.

The countrywide blackouts should have been a last resort.

She called on Brown to give a full briefing on Eskom's current capacity constraints to Parliament.

Solidarity said Eskom had been warned about skills shortages and an exodus of experts from the company for years.

"Those warnings fell on deaf ears," the trade union's energy industry head Deon Reyneke said in a statement.

"The time has arrived for Eskom to answer for its reluctance to address these issues."

Solidarity would ask Eskom to conduct a survey of its skills pool to address the shortcomings.