TAIPEI • Taiwan's state-owned electricity monopoly Taipower yesterday blamed human error during a test for a power cut that affected some four million homes the day before, and said it would offer discounts worth almost US$18 million (S$24 million) to affected customers.

The rolling blackouts went on for around five hours before normal supplies were resumed in the early evening, briefly affecting the world's biggest contract chipmaker, Taiwan Semiconductor Manufacturing.

Taipower said engineers had been carrying out tests at a substation as part of a future expansion project for a power plant in the southern port city of Kaohsiung.

However, they pressed the wrong switch, causing a sudden drop in voltage, and the problem then cascaded, leading to the blackout, it added.

Taipower will offer discounts to customers affected by the power cut.

In a text message just before the power failed early in the afternoon, the government said its grid did not have sufficient electricity capacity after the outage at the power plant in the southern port city of Kaohsiung.

Power went on and off intermittently in central Taipei, though it never totally went out.

REUTERS