NISO explains cause of Friday’s national grid collapse

The Nigerian Independent System Operator has said the national electricity grid collapsed on Friday due to the simultaneous tripping of multiple 330kV transmission lines and the disconnection of some power generation units.

PUNCH Online reports that the national electricity grid collapsed on Friday, with electricity generation plunging from above 4,500 megawatts to as low as 24 MW by about 1:30 pm.

All 23 power plants connected to the grid reportedly lost output during the incident, resulting in zero allocation to the nation’s 11 distribution companies.

In a preliminary statement issued on Saturday, NISO said the system-wide disturbance occurred at about 12:40pm and led to a total outage across the interconnected network.

“The Nigerian Independent System Operator wishes to inform the public that at approximately 12:40 hours on Friday, 23 January, 2026, the national grid experienced a system-wide disturbance, which resulted in a total outage across the interconnected network,” the operator stated.

According to NISO, preliminary operational reports showed that “the disturbance was associated with the simultaneous tripping of multiple 330kV transmission lines, alongside the disconnection of some grid-connected generating units.”

It added that “these events collectively contributed to the system collapse at the time indicated.”

The system operator said restoration activities began shortly after the collapse.

“Following the outage, system restoration activities commenced at about 13:15 hours, in accordance with established grid restoration and recovery procedures,” the statement read.

NISO said electricity supply had been restored to Abuja, Osogbo, Benin, Onitsha, Sakete, Jebba, Kainji, Shiroro and parts of Lagos, while efforts were ongoing in other parts of the country.

The operator said a probe into the incident had begun.

“A detailed investigation into the root and contributory causes of the disturbance is currently ongoing,” it said, adding that “the full restoration and stabilisation of the grid remains a top operational priority.”