JOHANNESBURG (Reuters) – Struggling South African power utility Eskom implemented planned power outages for the first time since March on Friday, ending a period of unusually stable power supply thanks to reduced demand during a coronavirus lockdown.

Eskom, which generates the vast majority of South Africa’s power but for years has had to manage supply from its ageing coal-fired power plants using blackouts, said the outages would last from 1000 GMT until 2000 GMT though the system could remain under pressure through the weekend.

“This loadshedding has been caused by an increase in plant breakdowns exceeding 3,000 megawatts of capacity,” Eskom said in a statement, using the local term for power cuts.

It added it was working to return broken-down generation units back to service and asked the public to limit their usage to take some of the burden off.

Eskom had to implement some of the worst blackouts in years in late 2019, putting further strain on South Africa’s already struggling economy which tipped into recession in the final quarter of the year.

But it received an unexpected respite when the pandemic struck and the government implemented a nationwide lockdown, taking many power-hungry industries offline for weeks.

The vast majority of the economy has now returned to work, and demand is also higher due to cold weather.

Its Chief Executive Andre du Ruyter told lawmakers in May that it expected only three days of stage-one power cuts, in which up to 1,000 megawatts are taken off the national grid, during the winter period.