Transpower is still looking for the fault in its circuit that caused yesterday's three-hour blackout across Northland.
Transpower engineers will inspect electricity towers today. Photo: AFP
A high-voltage circuit breaker tripped yesterday morning, leaving nearly 90,000 properties without power until midday.
Its chief executive Alison Andrew told Morning Report the company engineers had completed a flyover without identifying an obvious problem, and would be carrying out more investigations today.
"We've done the obvious checks, we've had a helicopter fly the circuit under question looking for signs of what may have caused the trip. Today we're going to be sending people up the towers to do some further inspections."
Ms Andrew said there were two circuits that supplied power to Northland, and one tripped while the other was undergoing maintenance yesterday.
The outage affected water supply, sewer systems and traffic lights. The Marsden Point Oil Refinery also had to completely power down for safety reasons.
She confirmed the failure was the third one this year in Northland, but said they were unrelated incidents. In May, Crews carrying out maintenance work tripped circuits bringing power supply down for two hours. In February a scrub fire under the power lines saw services shut down for an hour while fire crews worked nearby.
She said the cost of investing in more infrastructure to add more security to services in Northland were not considered to be justified.
"There's always ways you can increase the reliability of power but if we were to provide more contingency to the region it would require more lines and towers and that would come at a cost to the community. Certainly the costs of running another circuit to Northland is very expensive and we do normally already have two circuits running into Northland," she said.
"If we were to provide more contingency to the region it would require more lines and towers and that would come at a cost to the community." - Transpower chief executive Alison Andrew
No more investment needs to be made infrastructure.
certainly the costs of running another circuit to Northland is very expensive and we do normally already have two circuits running into Northland."
Any questions of compensation would need to be taken up with their retailer, she said.