After implementing stage 6 load shedding for the first time on Monday, Eskom says it will continue with stage 4 load shedding on Tuesday until 11pm.
Stage 4 allows for up to 4 000MW to be cut from the national grid.
Eskom has warned that cuts are likely to continue for the rest of the week as it battles severe capacity constraints caused by unplanned outages and flooding. On Monday it announced that heavy rains and floods at three power stations caused its already-reduced generation capacity to plunge further.
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"Eskom unreservedly apologises to all South Africans for the inconvenience during this difficult period," said Jabu Mabuza, Eskom's acting CEO and interim executive chairperson in statement.
Mabuza said a key reason for the implementation of stage 6 load shedding on Monday was the failure of a power supply line feeding electricity to incline conveyors feeding coal to silos at Medupi power station
"Technical teams worked around the clock and have resumed coal handling operations at Medupi power station," he said.
President Cyril Ramaphosa, in a statement on Monday, said that public anger over the 'devastating' power cuts was understandable, while Minister of Public Enterprises Pravin Gordhan apologised on eNCA.