Nearly 2 million customers of Manila Electric Co. (Meralco) were affected by rotating power interruptions on Tuesday after the Luzon grid was placed under Red Alert status due to tight power supply conditions and surging electricity demand.

The outages affected about 1.9 million users in portions of Bulacan, Cavite, Laguna, Metro Manila, Quezon, and Rizal after the National Grid Corporation of the Philippines (NGCP) directed Meralco to implement manual load dropping (MLD) to help stabilize the grid.

The affected customers account for roughly 23 percent of Meralco’s 8.3 million customer base as of end-March, or nearly one in every four customers served by the country’s largest power distributor.

Meralco said electricity service was fully restored by 12:14 a.m. today.

“Yesterday, May 13, Meralco was asked by NGCP to implement MLD — also given the Red Alert,” the company said in a statement on Wednesday.

The power distributor said it immediately sought the support of participants under its Interruptible Load Program (ILP) after NGCP again declared Yellow and Red Alerts in the Luzon grid on Wednesday.

Under the ILP, participating commercial and industrial establishments voluntarily run their own generator sets during periods of tight supply to help ease demand on the grid.

Meralco said it remains prepared to implement additional rotational power interruptions if necessary as part of its responsibility to help manage the system.

Meanwhile, the Department of Energy (DOE) attributed the strained grid conditions to a combination of forced outages, derated power plants, and elevated electricity demand driven by seasonal weather conditions.

The Luzon grid was placed under Red Alert from 4 p.m. to 10 p.m. today, with available capacity at 12,479 megawatts against projected peak demand of 12,595 MW. Yellow Alert was raised from 3 p.m. to 4 p.m. and again from 10 p.m. to 11 p.m.

Meanwhile, the Visayas grid was also placed under Yellow and Red Alerts, with available capacity at 2,413 MW against projected peak demand of 2,541 MW.

Energy Secretary Sharon Garin directed generation companies to immediately address plant issues and restore units to full capacity to help stabilize the grid.

“The DOE’s top priority is to protect consumers and maintain grid stability,” Garin said.

The DOE also ordered government offices to intensify energy efficiency and conservation measures, including reducing non-essential electricity use during peak demand hours.

Households and businesses were likewise encouraged to conserve electricity by setting air conditioners at 24 to 25 degrees Celsius, turning off unused appliances, and shifting the use of heavy-load equipment outside peak periods.

The agency said it continues to coordinate with transmission operator, distribution utilities, and generation companies to monitor conditions and implement measures to maintain stable power supply.