Power utility Eskom has warned that it may implement load shedding on Thursday evening.
The utility urged the public to reduce electricity usage, saying the power generation system is severely constrained.
Eskom has not instituted nationwide load shedding since the start of the lockdown in late March after power usage plunged as much of the economy was shut down. But it has been cutting power to localised areas in what it calls load reduction.
In a power update on Thursday morning, Eskom said that a generation unit at its Tutuka power station in Mpumalanga tripped, while another was taken off the grid, as well as a unit at Lethabo power station in the Free State.
In addition, the return to service of a generation unit each at Duvha and Kendal power stations has been delayed.
"All of these have added significant pressure to the generation system. Any additional breakdowns will compromise Eskom’s ability to supply the country through the peak demand period of 17:00 – 21:00."
The utility said the supply constraints may may persist through the weekend.