Electricity demand varies depending on the time of the day, day of the week or the seasons. For example, when people get home from work or start the evening routine, electricity demand often spikes as everyone turns on the lights and gets dinner started around the same time. This period of peak demand tends to occur when millions of households are using their appliances for cooking, bathing, heating in winter (and cooling in summer), lighting and entertainment all at the same time. 

In South Africa, peak demand periods occur in the mornings from 6am to 9am and in the early evenings from 5pm to 9pm. The evening peak is generally as a result of the impact of residential consumers. Winter usually sees a significant increase in the evening peaks and this is as a result of many people switching on their heaters.

Eskom has therefore re-launched the televised Power Alert initiative which informs the public about the real time status of the electricity network and empowers consumers to assist in balancing the supply and demand of electricity. The Power Alert system provides a real-time link into the four television broadcasters – SABC, etv, DStv – as well as Open View. The colour-coded alerts inform residential electricity users if the system is either stable, or under severe pressure. If under severe pressure, the public is requested to turn off “all unnecessary electrical appliances such as lights, geysers, pool pumps and non-essential appliances”.