ZESA identifies transmission line fault behind nationwide blackout

ZESA Holdings has identified the cause of the nationwide power outage that plunged Zimbabwe into darkness on Monday evening, saying the blackout was triggered by a major fault on a key transmission line that also destabilised the country's electricity generation system.

The power utility said the outage began at 6:24 pm on Monday, 6 July 2026, when a fault occurred on the Warren-Alaska 330kV transmission line, disrupting Zimbabwe's interconnections with neighbouring power utilities.

In a technical update issued on Tuesday, ZESA said the transmission fault led to wider instability across the national grid.

"At 1824 hours, a major electrical fault occurred on the Warren-Alaska 330kV line leading to loss of interconnections with neighbouring regional utilities," the utility said.

According to ZESA, the disruption then affected domestic electricity generation.

"Subsequently local generation was lost due to voltage instability and under frequency."

The explanation provides the first detailed account of what caused the nationwide blackout. Shortly after the outage on Monday evening, ZESA had only said that a technical fault had occurred on its network and that engineers were investigating the cause.

Restoration efforts began at 7:01 pm, less than an hour after the outage started. ZESA said engineers restored power by securing electricity supplies from Eskom, Kariba Power Station and Hydro Cahora Bassa, while Hwange Power Station Units 1, 2 and 3 were gradually brought back into service.

"We are pleased to advise that by 2200 hours, power had been successfully restored to most of our bulk supply points across the country," the utility said.

The power utility said work was continuing to synchronise the remaining generating units at Hwange Power Station and complete repairs at Warren Substation, which supplies electricity to parts of Harare.

"Our technical teams are working tirelessly to restore and synchronise the remaining units at Hwange Power Station and to conduct works at the Warren Substation, which supplies parts of Harare," ZESA said.

The nationwide outage affected homes, businesses and industries across Zimbabwe before electricity supplies were gradually restored later in the evening. ZESA apologised for the disruption and thanked customers for their patience while engineers worked to stabilise the national grid. The latest statement follows ZESA's initial announcement on Monday evening confirming that a nationwide outage had occurred due to a technical fault and assuring the public that restoration efforts were underway.

ZESA nationwide blackout