Cape Town - Eskom announced on Monday that it would implement stage 1 load shedding at 19:00.
"Due to increased electricity demand and a shortage of generation capacity due to power station units being on maintenance, Eskom has implemented stage 1 load shedding from 19:00 tonight and this is likely to continue until 22:00 this evening," Eskom said in a statement.
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Eskom, which has managed to stave off load shedding for more than five weeks, warned over the weekend that its daily supply from the Cahora Bassa hydroelectric scheme will be reduced by more than half to 650 MW from Monday.
READ: Cahora Bassa could flip switch on load shedding
This is due to planned maintenance it will undertake on the scheme together with Hidroelectrica de Cahora Bassa (HCB).
South Africa is currently importing 1 500 MW from Cahora Bassa on a daily basis.
Eskom warned that the power system will be tight, particularly over the weekday evening peak periods from Tuesday 15 to Friday 18 September and said it will utilise its emergency reserves to augment the capacity shortfall as a result of this planned outage.
The maintenance is expected to be completed on Sunday, 20 September and the hydroelectric scheme is expected to be back on full power on Monday, 21 September.
Eskom also warned of higher electricity consumption during the day as the weather begins to warm up. It called on all electricity users to continue using electricity sparingly and especially decreased usage of air-conditioners, geysers and pool pumps to reduce the risk of load shedding.