More than 850,000 houses were affected by the unexpected brownout that occurred in Metro Manila and seven provinces on Sunday, October 1, Manila Electric Company (Meralco) announced.

Aside from Metro Manila, provinces such as Pampanga, Bulacan, Cavite, Laguna, Batangas, Rizal, and Quezon experienced the said brownout.

According to Meralco, the unwanted power interruption was due to "grid disturbance" of the transmission line and other power plants in Luzon on Sunday evening.

"Your power supply may have been affected by a temporary system imbalance due to a sudden plant outage and may last for 10-15 minutes. Identification of affected areas is on-going," it said in a post.

The power interruption lasted from 15 minutes to 1 hour.

The electric distributor said further updates will be posted on its Facebook and X (formerly Twitter) pages.