"As part of its support for the Earth Hour campaign, Eskom measured the reduction in electricity used during the hour (between 8.30pm and 9.30pm) against typical consumption for this time on an average Saturday evening," said the power utility on Sunday, 24 March.
Eskom had also switched off non-essential lighting at all its offices around the country, except at strategic facilities for security reasons.
Earth Hour started in 2007 in Sydney, Australia, when 2.2 million people and more than 2 000 businesses turned their lights off for one hour to take a stand against climate change. Support for the initiative has increased each year.
Last year, Eskom measured an estimated reduction of approximately 402MW during the hour-long campaign - enough electricity to power the city of Mangaung (Bloemfontein).
This year's figure shows that more and more South Africans are seeing the value of switching off what they are not using.
Eskom's support is in line with the 49M energy efficiency movement that was launched in March 2011 by Deputy President Kgalema Motlanthe and Minister of Public Enterprises, Malusi Gigaba.
The campaign encourages individuals and businesses to lead energy-smart lifestyles, to save power, save the planet and save their pockets.
Turning off the lights saves hundreds of tons of coal from being burned to produce electricity, so that less greenhouse gases are released into the atmosphere.
