NISO links national grid collapse to multiple 330kV line trips

The Nigerian Independent System Operator says Friday’s nationwide power outage was caused by a system-wide disturbance from multiple 330kV transmission line trips and the disconnection of some grid-connected generating units.

The disclosure was made by the system operator in an operational update released following the collapse of the national grid.

The incident, which occurred around midday on Friday, led to a total shutdown of electricity supply across the country and has been confirmed as the first grid collapse recorded in 2026.

Operational data from NISO showed that electricity supply to all 11 distribution companies fell to zero megawatts, plunging homes, businesses, and critical infrastructure nationwide into darkness.

The outage once again demonstrated long-standing concerns about the fragility of Nigeria’s electricity transmission network and the recurring instability of the national grid.

What NISO is saying 

NISO said preliminary findings from its operational assessment point to multiple failures on the high-voltage transmission network, which ultimately destabilised the entire system.

The operator noted that the disturbance affected both transmission infrastructure and power generation units connected to the grid.

“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,” NISO said.

“These events collectively contributed to the system’s collapse at the time indicated.” 

“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,” the operator stated.

NISO added that investigations into the root cause of the incident are ongoing, while full restoration and stabilisation of the grid remain a top priority.

Get up to speed 

The national grid collapse occurred on Friday afternoon, with power generation across the interconnected network falling to zero at approximately 12:40 pm.

Shortly after, load allocation to the country’s 11 electricity distribution companies dropped to zero megawatts at about 1:00 pm, confirming a complete system failure.

• The incident has been confirmed by NISO as the first national grid collapse recorded in 2026.
• Restoration activities commenced at about 1:15 pm, in line with established grid recovery procedures.
• Several generation and transmission nodes were gradually brought back online as part of the step-by-step restoration process.
• Electricity supply has since been restored to several major cities and power stations, with work ongoing in other areas.

Nairametrics understands that grid restoration in Nigeria typically follows a phased process to avoid further system instability during recovery.

What you should know

Nigeria’s national grid has experienced repeated partial and total collapses in recent years, raising concerns among industry stakeholders and electricity consumers.

The federal government has previously attributed frequent nationwide blackouts to the inability of electricity distribution companies to fully absorb the power generated, a situation that often results in grid imbalances.

• Data from the Nigerian Electricity Regulatory Commission shows that the grid recorded several partial and total collapses in 2024.
• These incidents have intensified concerns about the reliability and resilience of the country’s electricity infrastructure.
• Transmission constraints and weak grid management continue to pose risks to stable power supply.

Stakeholders have repeatedly called for sustained investment in transmission infrastructure and operational efficiency.