MANILA, April 18 -- The Luzon and Visayas grids were placed under alert status for the third consecutive day on Thursday, due to thin power supply.

The National Grid Corporation of the Philippines (NGCP) put the Luzon grid under red alert status from 3 to 4 p.m. and 8 to 10 p.m.

Yellow alert status in the Luzon grid today would be in effect from 1 to 3 p.m., 4 to 8 p.m., and 10 to 11 p.m.

Likewise, the Visayas grid was also placed under yellow alert from 1 to 9 p.m.

NGCP places a grid under red alert when power supply cannot meet the consumer demand in the transmission grid's regulating requirement.

On the other hand, yellow alert is issued when the operating margin is not enough to meet the transmission grid's contingency requiremen...