A system-wide disturbance triggered by the tripping of multiple 330kV transmission lines and the disconnection of some generating units, caused Friday’s national grid collapse, the Nigerian Independent System Operator (NISO) has said.
NISO data showed load allocation to 11 electricity distribution companies dropped to zero megawatts (MW) at 1: 00 pm, marking the first grid collapse of 2026.
In a statement following the incident, the operator said power generation dropped to zero MW at about 12:40 pm, resulting in a total outage across the interconnected network.
Said the operator: “Preliminary operational reports indicate that the disturbance was associated with the simultaneous tripping of multiple 330kV transmission lines, alongside the disconnection of some grid-connected generating units.
“These events collectively contributed to the system collapse at the time indicated”.
The operator said power restoration was underway, with electricity supply already restored to key cities, including Abuja and Lagos, following the grid collapse.
Said NISO: “Following the outage, system restoration activities commenced at about 13:15 hours, in accordance with established grid restoration and recovery procedures.
“As of the time of this update, electricity supply has been successfully restored to Abuja, Osogbo, Benin, Onitsha, Sakete, Jebba, Kainji, Shiroro, and parts of Lagos, while restoration efforts are continuing progressively in other parts of the country”.
NISO added that a detailed investigation into the causes of the grid collapse was ongoing, with full restoration and stabilisation of the grid remaining a top priority.
