Mayor Jerry Treñas asked the National Grid Corporation of the Philippines (NGCP) to issue a detailed advisory explaining the root cause of the widespread power outage that hit Iloilo City on Monday, Feb. 20.

The city and other areas in Western Visayas experienced the unscheduled power outage for more than eight hours.

“I trust that you give this matter your preferential and profound attention,” Treñas said in his letter to the country’s grid operator.

According to the mayor, the power outage “brought inconvenience not only to the Ilonggos in and outside their homes but also affected transactions in both public and private offices and businesses causing backlogs and missing deadlines on that day.”

In a statement, NGCP said it shut off its lines after detecting a disturbance to protect its system.

“NGCP is investigating the root cause of the incident.”

NGCP is a privately owned corporation that operates the grid, which connects power plants to distribution utilities. The grid infrastructure is owned by government through Transco or National Transmission Corp.IMT