Several areas in Luzon had no power for an hour Tuesday evening because three power plants supplying the Luzon grid shut down.
Energy Secretary Jericho Petilla said there was an abrupt drop in power supply when the Santa Rita, Pagbilao, and Quezon plants went offline at 6:34 p.m. due to line trippings.
The affected areas included the cities of Caloocan, Quezon, Las Pinas, and Manila and the province of Cavite.
The National Grid Corporation of the Philippines was trying to determine what caused the line trippings as of press time.
The last time that a major line tripping occurred was in May when five power plants shut down, causing a 10-hour power interruption in Metro Manila and nearby provinces.