Eskom said electricity grid was severely constrained following unplanned plant breakdowns.

"We have experienced a loss of additional generation. As a result, it has become necessary to implement Stage 2 rotational load-shedding from 4pm until 11pm in order to protect the power system from a total collapse," it said.

The company said in order to avoid load-shedding it needed to contain the capacity loss of unplanned breakdowns at below 9,500 megawatts and this has been exceeded.

"In the event generator breakdowns are experienced beyond 10,500MW there will be high usage of emergency resources (diesel and pumped storage generators), which may lead to load-shedding if the supply constraints is sustained for a long duration.

"The severe supply constraint being experienced has come about due to high levels of unplanned breakdowns that have exceeded the 10,500MW limit."

African News Agency (ANA)