Power supply restored after partial grid collapse- NISO

The Nigerian Independent System Operator (NISO) has confirmed that electricity supply has been fully restored across Nigeria following a partial collapse of the national power grid earlier today.

According to NISO, the grid disturbance occurred at exactly 2:01 pm on Monday, December 29, 2025, triggering widespread power outages in several parts of the country. Data obtained by our correspondent showed that power generation, which had peaked at about 4,800 megawatts, plunged sharply to 139MW by 3 pm.

In a statement issued tonight, NISO said the incident was caused by the tripping of multiple power generation units and critical 330-kilovolt transmission lines, further destabilising the already fragile national grid.

“The National Grid experienced a system disturbance at 14:01 hours on Monday,29 December 2025, leading to a partial collapse. Preliminary reports indicate the tripping of several generating units and key 330kV transmission lines, resulting in widespread electricity disruption,” the statement read.

The operator noted that the incident occurred amid ongoing gas supply constraints, worsened by the vandalisation of the Escravos–Lagos gas pipeline on December 10, 2025. The damage significantly reduced gas supply to thermal power plants, forcing several generation companies to cut output and exposing long-standing weaknesses in the power system.

NISO explained that the gas shortages further weakened the grid, making it more vulnerable to system disturbances.

Despite the disruption, the Delta generation complex successfully isolated itself from the national grid and operated in island mode at the 132kV sub-transmission level. This intervention ensured uninterrupted electricity supply to Oghara, Amukpe, Benin, and Efunrun substations.

“A total of 114 megawatts was delivered from four units at the Delta Thermal Power Station,” NISO disclosed.

The system operator said it immediately activated emergency response measures in line with established operational procedures, using dispatch and monitoring tools at the National Control Centre in Osogbo.

Following hours of coordinated recovery efforts, NISO confirmed that power supply has now been fully restored nationwide.

“Supply has been fully restored to all parts of the country, and system stability has been normalised,” the operator stated.

NISO added that investigations are ongoing to determine the exact cause and sequence of events that led to the partial collapse, assuring Nigerians that corrective measures would be implemented to prevent future occurrences.

Grid disturbances and collapses have remained a recurring challenge in Nigeria’s power sector, often linked to gas shortages, weak transmission infrastructure and operational constraints. Since the unbundling of the sector, successive governments have pledged reforms aimed at improving grid stability and transmission capacity.

Reaffirming its commitment, NISO said it would continue to adopt proactive grid management practices to ensure reliable electricity supply nationwide.

“NISO reassures Nigerians of its commitment to the stability and reliability of the National Grid through the application of best operational practices,” the statement concluded.