Although the power supply system is constrained, there is a low risk of rolling power cuts, Eskom said on Thursday.

"The risk of load shedding is expected to be low to medium," spokesperson Khulu Phasiwe said in a statement.

"Some of our generating units have come on line. We are expecting others to come on line this afternoon."

It was expected these would stabilise the power grid.

Phasiwe said Eskom would do all it could to ensure there was electricity on Thursday night.

"We are not doing what we are doing because tonight is the state-of-the-nation address. It is because some of our generating capacity is back."

He said Eskom did not aspire to implement load shedding at any given point.

"We only implement it when we really have to, when our generators have broken down."

Eskom implemented stage two rolling power cuts from 18:00 to 22:00 on Wednesday.

This was due to a shortage of generation capacity, with several units out of service due to planned and unplanned outages.

The power system remained severely constrained and would be for the rest of the week, Eskom said at the time.

Phasiwe urged people to switch off all nonessential appliances.