File photo: Ian Landsberg/African News Agency (ANA).

* This story has been updated

Johannesburg - South Africans have been warned to brace for another bout of load shedding on Thursday evening from 4pm to 11pm.

This was announced by Eskom in a brief tweet, which explained that this was due to a "shortage in capacity". 

The parastatal later released a statement where it said: "Eskom would like to inform South Africans and all its customers that the electricity system is severely constrained. In the power alert issued earlier this morning Eskom informed that unplanned breakdowns were at 12 300MW, and that there was a probability of load shedding at short notice if unexpected shifts, such as additional unplanned breakdowns, were experienced.

"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.

"In the system status briefing of September 4, 2019 Eskom warned that in order to avoid load shedding, unplanned breakdowns needed to be contained at below 9 500MW. 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.

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

"We unreservedly apologise to South Africans for the negative impact this may have on them and want to assure the nation that we continue to work tirelessly to ensure security of energy supply."

The latest announcement comes days after the embattled entity assured citizens there would be no load shedding but warned that unplanned breakdowns in its system could result in load shedding at short notice.

South Africa last experienced load shedding early last month.

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