Eskom implemented stage two rolling power cuts on Tuesday to help bolster power supply for the rest of the week, acting CEO Dan Marokane said.

"We moved to stage two in order to manage our reserves at our pumped storage schemes and gas turbines so that we can better manage the rest of the week," Marokane said in a statement.

Eskom began with stage one rotational power cuts on Tuesday morning, but later escalated to stage two. This would continue until 10pm.

Stage one allows for up to 1000MW of the national load to be cut, stage two for up to 2000MW, and stage three for up to 4000MW.

Eskom said the intensified power cuts were necessary because of a shortage of generation capacity.

"At our pumped storage schemes (which use water to generate electricity), the dam levels are low because we were not able to pump the water back to full capacity over the weekend," it said on Tuesday afternoon.

This was because Eskom had to use its pumped storage schemes over the weekend to meet demand.

"Ordinarily, the weekends are used to pump our dam levels to maximum capacity in preparation for the forecasted increased demand in electricity during the week."

Earlier, Eskom spokesman Andrew Etzinger warned there was a good chance of power cuts.

"The grid is exceptionally tight. There is a medium to high chance of load shedding today [Tuesday] if we do see further technical challenges developing."

Shortly after 9am the power utility tweeted: "Eskom will implement load shedding stage one from 10.30am today. It is likely to continue until 10pm. We will give updates throughout the day."

Etzinger said 25 percent of Eskom's generator capacity was out because of technical problems.

"We won't go to stage three unless it is absolutely necessary."