The Nigerian Independent System Operator has attributed Friday’s national grid collapse to a system-wide disturbance triggered by the tripping of multiple 330kV transmission lines and the disconnection of some generating units.
The operator said data from the incident showed that load allocation to the 11 electricity distribution companies fell to zero megawatts at about 1pm, marking the first collapse of the national grid in 2026.
In a statement issued after the outage, NISO said power generation dropped to zero megawatts around 12:40pm, leading to a total shutdown of the interconnected electricity network.
“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,” the operator stated.
It added that the combined impact of the incidents resulted in the system collapse.
NISO said restoration efforts began shortly after the blackout, noting that electricity supply had already been restored to some major locations.
“Following the outage, system restoration activities commenced at about 13:15 hours, in accordance with established grid restoration and recovery procedures,” the operator said.
It listed Abuja, Osogbo, Benin, Onitsha, Sakete, Jebba, Kainji, Shiroro and parts of Lagos among areas where supply had been restored as of the time of the update, adding that recovery was ongoing in other parts of the country.
The operator said investigations were still ongoing to determine the full cause of the disturbance, stressing that complete restoration and stabilisation of the grid remained its priority.