The Nigerian Independent System Operator (NISO) said it has commenced investigations into the cause of the partial collapse of the national electricity grid on Monday.
In a statement issued by its management Monday night, NISO confirmed that the system disturbance occurred at about 2:01pm, resulting in the tripping of several generating units and critical 330kV transmission lines, which disrupted electricity supply across parts of the country.
According to the operator, the incident came against the backdrop of existing weaknesses in the national grid following the vandalisation of the Lagos–Escravos–Lagos gas pipeline on December 10, 2025.
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According to NISO, the damage to the gas infrastructure had constrained power generation and further exposed the grid to instability.
“Investigations into the cause and sequence of events leading to the system disturbance are currently ongoing,” NISO said.
It added that findings from the probe would guide measures to prevent a recurrence of similar incidents.
NISO disclosed that the Delta generation complex was able to operate successfully in island mode at the 132kV sub-transmission level.
This, the operator said, had ensured continued electricity supply to Oghara, Amukpe, Benin and Efunrun 132kV substations, with a total of 114 megawatts generated from four units at the Delta Thermal Power Station.
The system operator explained that in line with established operational procedures, it immediately activated system response measures through its dispatch and monitoring tools at the National Control Centre in Osogbo.
These interventions, it said, led to the full restoration of supply nationwide and the normalisation of system stability.
NISO reassured Nigerians that it remains committed to proactive grid management and the application of best operational practices to enhance the reliability and stability of the national grid, even as it works to address vulnerabilities exposed by recent disruptions.
The operator also pledged that appropriate corrective actions would be implemented once investigations are concluded, as part of broader efforts to strengthen the resilience of Nigeria’s electricity transmission network.
THE WHISTLER had earlier reported that Nigeria’s national power grid suffered another collapse, plunging several cities across the country into darkness on Monday afternoon.
Data obtained from the website of the Nigerian Independent System Operator (NISO) showed that electricity generation dropped sharply from 2,660.77 megawatts (MW) at about 2:00 p.m. to as low as 139.92MW by 3:00 p.m., indicating a total system failure.
Checks further revealed that key generating stations, including the Shiroro Hydropower Plant and Delta Gas Power Plant, were on the grid and contributing power before the collapse occurred.
The latest incident came barely a day after the Federal Government announced that full electricity generation had been restored following the repair of the vandalised Lagos–Escravos gas pipeline, a critical supply route for several thermal power plants nationwide.
Confirming the development, Abuja Electricity Distribution Company (AEDC) and Eko Electricity Distribution Company (EKEDC) said in separate statements that the system disturbance occurred at about 2:00 p.m.
According to the DisCos, the blackout was caused by a loss of power across the entire national grid, leading to widespread outages within their respective networks.