The incident, which occurred north of Auckland on June 20, resulted in power cut to about 100,000 properties in the Northland region of northern New Zealand. Full power was restored only on Sunday.
Transpower chief executive Alison Andrew stated that a crew from Omexom was undertaking routine maintenance on the base plates, which secure the tower to the ground, when the pylon collapsed.
"All the nuts securing the tower to the base plate on three legs have been removed, which has caused the tower to lift off the base plate and fall," she said in a statement.
"It is unprecedented and inconceivable that so many nuts were removed at once."
A full investigation had been launched, she said.
"While we are very grateful that no one was hurt when the tower fell, the failure to follow procedure resulted in a significant power outage that had a real impact on the people of Northland," she added.
"We are committed to learning from this event and implementing any additional controls that may be identified."
Omexom's managing director Mornez Green commented that the incident was unprecedented.
The workers involved had been stood down pending the investigation, he said.
"I can assure you we will be open and transparent in the investigation."
-- BERNAMA
