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The Nigerian Independent System Operator (NISO) has disclosed that power supply has been restored nationwide after the nation’s electricity grid experienced a system disturbance that led to a partial collapse on Monday.
NISO disclosed that the incident occurred at exactly 2:01 pm on Monday, December 29, 2025, disrupting electricity supply across several parts of the country.
In a statement signed by its management on Monday night, the system operator said the disturbance triggered the tripping of multiple power generation units and critical 330 kilovolt transmission lines, worsening the already fragile state of the national grid.
“The Nigerian Independent System Operator wishes to inform the general public and relevant stakeholders that the National Grid experienced a system disturbance at 14:01 hours on Monday, 29 December 2025, that led to a partial collapse.
“Preliminary reports indicate that the disturbance involved the tripping of several generating units and critical 330kV transmission lines, resulting in a widespread impact on electricity supply across parts of the country,” the statement read.
The latest grid disturbance occurred amid ongoing gas supply challenges following the vandalisation of the Escravos-Lagos gas pipeline on December 10, 2025, which significantly curtailed gas availability to thermal power plants.
The damage to the pipeline had earlier triggered widespread power shortages, forcing several generation companies to reduce output and once again exposing long-standing structural weaknesses in the national grid.
Despite the disruption, NISO disclosed that the Delta generation complex successfully isolated itself from the national grid and continued operations through island mode at the 132kV sub-transmission voltage level.
According to the system operator, the intervention ensured uninterrupted electricity supply to Oghara, Amukpe, Benin and Efunrun 132kV substations, with a total generation of 114 megawatts delivered from four units at the Delta Thermal Power Station.
NISO said it promptly activated emergency response measures in line with established operational procedures, noting that preliminary findings indicated the disturbance involved the tripping of several generating units and critical 330kV transmission lines, which resulted in widespread power outages across parts of the country.
The operator explained that the successful island-mode operation of the Delta generation complex helped stabilise supply to affected areas while broader recovery efforts were underway, coordinated from the National Control Centre in Osogbo using dispatch and monitoring tools.
NISO later confirmed that electricity supply had been fully restored nationwide and that system stability had been normalised after several hours of coordinated recovery operations.
The system operator added that investigations were ongoing to determine the precise cause and sequence of events that led to the partial collapse, assuring Nigerians that appropriate corrective measures would be implemented to prevent a recurrence.
Grid collapses and system disturbances have remained a recurring challenge in Nigeria’s power sector, often linked to gas supply shortages, weak transmission infrastructure and operational constraints.
NISO, which recently assumed system operation responsibilities following power sector reforms, reaffirmed its commitment to proactive grid management and the application of best operational practices to ensure the stability and reliability of the national grid.
