Eskom has confirmed that it will implement stage 4 load shedding from 14:00 on Friday, despite already using diesel-powered open cycle gas turbines and pumped storage schemes to supplement capacity.
Stage 4 allows for up to 4 000 MW - just under 10% of Eskom's nominal capacity - to be cut from the national grid.
"For now, the prognosis is that we will implement stage 4 load shedding between 14:00 and 06:00 tomorrow. Should anything change, Eskom will advise consumers,” said the utility's spokesperson Nto Rikhotso.
This comes after the utility implemented rotational power cuts overnight on Thursday. The cuts continued at stage 2 into Friday. Eskom previously said that these stage 2 power cuts would continue until until 06:00 on Saturday morning, but this has now been upgraded to stage 4.
In an earlier update the utility said unplanned breakdowns were still above 12 500 MW - more than a quarter of its generating capacity - and its technical teams had been unable to return units to service from planned maintenance or unplanned outages. Unplanned outages have now risen to above 13 000MW, it said.
The utility said wet coal had contributed to the need to increase the load shedding stage from 2 to 4.
"With the incessant rain, we are beginning to experience coal-handling problems at a number of our power stations as a result of wet coal, which has led to generation units being unable to produce power. If the wet weather persists, we are likely to implement load shedding throughout the weekend."
"A concerted collective effort to reduce demand can help to avoid or lessen the level of load shedding. As we are experiencing rainy and cold weather conditions in some parts of the country, we ask that you use efficient heating to keep warm and switch off your geysers over peak periods," it said.