TAIPEI, March 3 (Reuters) - Taiwan on Thursday blamed negligence during annual maintenance at a major power plant for a mass outage across the island that caused the lights to go off for more than 5 million households, though the crucial semiconductor sector was largely unaffected.
The power cut began shortly after 9 a.m. (0100 GMT) after a problem at the Hsinta power plant and while it impacted all parts of Taiwan the most extensive problems were in the south, especially the major port city of Kaohsiung.
Power has now mostly been restored, at least in northern Taiwan, and efforts are continuing in the south to reconnect those still without electricity.
Cabinet spokesperson Lo Ping-cheng said state-run operator Taipower's initial probe found the outage was caused by human negligence during annual repairs of a generator at the Hsinta plant, also located in Kaohsiung.
The statement did not elaborate, though it added that Taipower's chairman Yang Wei-fu had submitted his resignation.
Hsinta is a coal-fired station that provides about a seventh of Taiwan's power. President Tsai Ing-wen will visit the plant on Friday, her office said.
"I am very sorry for this major loss of electricity, and am extremely apologetic for the inconvenience caused, especially for the south," Economy Minister Wang Mei-hua told reporters earlier on Thursday.
The cut affected about a third of Taiwan's power supply, hitting some 5 million households, Wang said.
Back-up power supply was at 24% at the time of the incident, Wang said, adding that it was not triggered by insufficient supply, the root cause of major outages in May, when Taiwan was grappling with a drought and heat-wave.
The Hsinchu science park, home to many large chip companies such as Taiwan Semiconductor Manufacturing Co (TSMC) , said it did not suffer outages.
The southern Tainan Science Park, where TSMC also has plants, said it experienced a sudden drop of voltage in the morning which, however, did not affect production.
TSMC said "power dips" at some of its wafer fabrication plants ran from about 400 milliseconds to more than a second. The company later said there had been no impact on operations.
After last year's two major outages brought criticism for the government, Tsai has vowed to scrutinise electricity management.
Our Standards: The Thomson Reuters Trust Principles.