There was a high risk of rolling blackouts on Tuesday due to a "very constrained" power system, Eskom said.

"The power system is currently very constrained and there is a high probability of load shedding later this afternoon," spokesperson Khulu Phasiwe said.

"It important to note that we have not declared an emergency or announced load shedding, but we are seeing a lot of demand on the system and expect it to get worse this afternoon when people get home."

That was when people used their stoves and other appliances.

"On a technical side, the engineers are doing all things possible to bring all generators back on the grid," Phasiwe said.