Correctional Services said that “matters are under control” at Johannesburg’s Sun City Prison on Wed.
Eskom is punting rationing electricity for five years until it can meet national demand in 2013.
"We have run out of reserve capacity. The biggest lever [to increase this] is to reduce demand," chief executive Jacob Maroga said yesterday.
Each customer would have a consumption quota and there would be "serious financial implications or incentives" for going over, or maintaining usage below this.
Earlier, Maroga said the ration would be calculated by using an average consumption minus a specific percentage reduction.
He said details would be worked out in the next few weeks.
Maroga said saving energy was about changing the behaviour of customers.
"How do we hardwire some of these things that we want [people] to do?," he said, citing switching off geysers as an example.
Maroga said Eskom knew that load shedding was very disruptive. Life-threatening situations such as when power went out during an operation were "pretty traumatic", he said.
Maroga warned that double-digit increases would be required in electricity tariffs for years.
"That's the reality of the cost of the plants we have to bring on stream in order to bring what is required for South Africa to have a [sufficient energy] supply."
Maroga said South Africa both imported and exported electricity to neighbouring countries. But these countries were never supplied at South Africa's expense. He said Eskom did not believe the current blackouts in Zimbabwe were related to South Africa's energy crisis.
"They seem to have a technical problem which is not necessarily related to what is happening [in South Africa]."
He said the government was considering adjusting taxation and import duties on portable generators.
Eskom would try to provide accurate schedules of power cuts, but the "level and depth of load shedding" meant it could not always stick to its commitment to keep power cuts to two hours at a time.
The power utility has already asked businesses to cut their power consumption by between 10 and 15percent.
After meeting top business leaders in Midrand yesterday about the energy crisis, Maroga said "voluntary saving targets" had been discussed with the 131 executives from 38 companies.
He would aspire to a 20 percent reduction. "That reduction will relieve and reduce the probability of load shedding."
Eskom had set up a task team with key business leaders. The team would meet "very, very shortly to come up with concrete solutions of how we can move forward".
The Democratic Alliance said yesterday that a shortage of key staff at Eskom was "severely undermining" the utility's ability to keep its power stations running.
The DA's public enterprises spokesman, Manie van Dyk, said Eskom had denied its staffing policies had contributed to the electricity crunch. - Sapa