Stage two rolling blackouts were scheduled for Wednesday, Eskom said.
“Eskom will implement stage two load shedding from 4pm today, which is likely to continue until 10pm this evening,” the power utility said in a statement.
“This is due to a shortage of generation capacity as several units are currently out of service due to planned and unplanned outages.”
Eskom said any additional changes on the already “vulnerable and constrained power system” could lead to a change in the stage at short notice.
It said load shedding was implemented as a “last resort to protect the power system from a complete blackout”.
All customers should reduce the load on the electricity grid by switching off geysers, air conditioners, pool pumps and all non-essential appliances, Eskom said.
“Commercial customers, particularly shopping centres and office blocks, can also make a big difference by switching off non-essential lights and not leaving office equipment such as photocopiers and computers in standby mode after hours,” it said.
The load shedding schedules were available on the Eskom website.
During stage one blackouts 1000MW of the national load is cut and 2000MW during stage two.
In recent months, Eskom has battled to keep the lights on since the collapse of one of its coal storage silos, diesel shortages, and maintenance issues.
Because of these constraints, Eskom says it has been forced to explore options for further review of tariff increases for the 2015/16 financial year.
The National Energy Regulator of SA has confirmed Eskom is formalising an application to reopen the multi-year price determination, allowing for a further increase in electricity tariffs.
Two weeks ago, Eskom chief executive Tshediso Matona, finance director Tsholofelo Molefe, group capital executive Dan Morokane, and commercial and technology executive Matshela Koko were asked to step aside as the power utility embarked on a fact-finding inquiry. SAPA