“We currently have 4,858MW on planned maintenance. while another 14,521MW of capacity is unavailable due to breakdowns and delays,” said the power utility.
Stage 3 rolling blackouts will be implemented from 1pm, Eskom warned in an alert on Wednesday.
The power cuts will continue overnight until 6am on Thursday.
The power utility said load-shedding had to be introduced “following the loss of generation units and to replenish emergency generation reserves”.
“This load-shedding is necessary as the power generation system is still severely constrained due to high generation unit breakdowns during the past three days, as well as the need to replenish diminishing emergency generation reserves.
“The outlook for the power system is unpredictable and there is a high probability of load-shedding continuing on Thursday,” said Eskom.
A generation unit each at the Lethabo, Kendal and Duvha power stations were taken offline for repairs early on Wednesday, adding to a high number of breakdowns and units that failed to return to service as planned.