Johannesburg - Deliberate power cuts, the first of this winter, took place countrywide on Wednesday night, electricity giant Eskom said.
"Due to unavailability of some of our generators, we are implementing load shedding for an hour," said spokesperson Andrew Etzinger on Wednesday evening.
He said two units at Duvha and Kendal power stations had tripped and a portion of the capacity usually imported from Cahora Bassa became unavailable.
"As a result, a reduction in electricity demand was required between 18:00 and 20:00 in order to balance the electricity system, which was implemented according to Eskom's load shedding schedule.
"We sincerely apologise for the inconvenience to affected customers.
"We anticipate that the system will remain tight tomorrow [Thursday] evening between 17:00 and 21:00 and once again appeal to all energy users to use electricity sparingly during this period."
He said that in an effort to avoid load shedding, all electricity users were urged to switch off non-essential appliances, pool pumps and geysers between 17:00 and 21:00.
"Commercial customers, particularly shopping centres and office blocks, can make the biggest difference by switching off non-essential lights and not leaving office equipment such as photocopiers and computers in standby mode after hours," he said.