The Nigerian Independent System Operator, (NISO), said power supply has been restored nationwide following Monday’s partial collapse of the nation’s electricity grid.
“Supply has been fully restored to all parts of the country and the system stability normalised,” it confirmed.
The incident,which started at 2:01 pm, affected electricity supply across several parts of the country, it said in a statement.
Most electricity distribution companies confirmed the grid loss to their customers.
NISO has begun probe into the latest grid loss to prevent future occurrence, it quoted in a statement.
The disturbance, NISO noted, caused the tripping of multiple power generation units and critical 330 kilovolt transmission lines, worsening the already fragile state of the national grid.
It added:“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.”
Gas constraints further weakened the grid, making it vulnerable to system disturbances, according to the operator.
NISO said that despite the disruption , the Delta generation complex successfully isolated itself from the national grid and continued operations through island mode at the 132kV sub-transmission voltage level.
The intervention ensured uninterrupted power supply to Oghara, Amukpe, Benin and Efunrun 132kV substations, it said, adding that:“A total generation of 114 megawatts was delivered from four units at the Delta Thermal Power Station.”
It quickly activated emergency response measures in line with established operational procedures.
The statement added:“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.
“However, the Delta generation complex successfully operated in island mode at the 132kV sub-transmission voltage level. This enabled the continued supply of electricity to Oghara, Amukpe, Benin, and Efunrun 132kV substations, with a total generation of 114 megawatts from four units at the Delta Thermal Power Station.
“In line with established Operational Procedures, NISO promptly initiated system response measures using its dispatch and monitoring tools at the National Control Centre in Osogbo,” the statement added.
Besides, investigations were ongoing to determine the precise cause and sequence of events that led to the partial collapse, it said.
It further assured Nigerians that corrective measures would be implemented to prevent a recurrence.
“Investigations into the cause and sequence of events leading to the system disturbance are currently ongoing. Appropriate measures shall be put in place to forestall future recurrence of such major system incidents”
“NISO reassures Nigerians of its continued commitment to proactive grid management and the application of best operational practices to ensure the stability and reliability of the national grid.”
