Lt. Col. Daniel Lucero, spokesman for the Armed Forces Southern Command (Southcom), said initial field reports indicated that "a tree falling down on a high-tension wire" caused the trip-off.
An estimated 2.4 million residents of the cities of Davao, Cagayan de Oro, General Santos, Butuan and Cotabato were without electricity after a 138-kilovolt line tripped at about 10:45 a.m.
Electricity went off at around 11:30 a.m. yesterday and Southern and Central Mindanao were without power for four hours and 30 minutes.
At 3:05 p.m., power was restored in most of Davao City, but certain areas of Central Mindanao still had no electricity as of yesterday afternoon.
Rolando Bacani, vice president for system operations of National Transmission Corp. (Transco), said the power failure was caused by the overloading of the 138-kilovolt Lugait-Tagoloan transmission line in the mountainous area near Misamis Oriental.
Bacani said the tripping occurred after the Lugait-Tagoloan line sagged below its safe clearance level and "came into contact" with trees.
Out of eight toppled transmission lines, three had been repaired and two others are being fixed, he added.
Two power plants in Lugait town at the boundary of Misamis Oriental and Lanao del Norte were reportedly shut off after experiencing some technicalities.
Officials of the National Power Corp. said they were not ruling out sabotage by the Moro Islamic Liberation Front (MILF).— Edith Regalado, Donnabelle Gatdula, Mike Frialde, Marichu Villanueva, John Paul Jubelag, Bong Fabe, AFP