The extent of the outage. Photo: Supplied
Most people who have been without power for hours in the Far North have had their connection restored.
Power was cut to more than 23,000 homes and business just after 5.20pm on Thursday with the outage covering the entire southern part of the district, including the Bay of Islands, Kaikohe, South Hokianga and Whangaroa.
In an update shortly before midnight, lines company Top Energy said it had progressively restored power to most households.
The lines company earlier said it was aiming to restore power to affected properties by midnight.
According to its outage centre, the fault was on a sub-transmission feeder. Investigations showed half of the 33-kilovolt switchboard was damaged and could not be returned to service on Thursday night. However, the other half of the switchboard had been salvaged.
Top Energy said capacity was reduced as it was currently running on its smallest transformer at Kaikohe, meaning it could not guarantee full security of supply until repairs were completed.
A diesel generator was being used at Omania to support the customers in the southern network.
It asked people to conserve power until Friday morning.
"We'll regroup first thing tomorrow [Friday] to assess the full extent of the damage. The damaged 33kV switchboard is approximately 10 years old, they have a normal life of about 50 years," the company said.
"We need to confirm repair timelines and what replacement equipment may be required. The supplier will be working with us on site in the morning."
Top Energy workers at Kaikohe substation. Photo: RNZ / Peter de Graaf
A Kaikohe woman living near the substation said she heard a loud boom about 5.20pm.
She went outside to investigate and saw the doors to a building at the substation appeared to have blown open.
Smoke or water vapour was coming out of the doors.
No one was present at the substation so she called 111.
FENZ sent volunteer fire crews from Kaikohe and Ōkaihau.
She said three firefighters entered the building wearing protective clothing and breathing apparatus.
There was no sign of fire that she could see.
The fire crews had left but Top Energy workers continued to come and go from the substation on the outskirts of Kaikohe.
It's exactly the same area that was affected by a huge outage last Friday, just six days ago.
Kaikohe substation provides power to much of the Far North. Photo: RNZ / Peter de Graaf
In that case, the cause was a tree falling on a 33-kilovolt line near Mount Pokaka, south of Kerikeri, but it was not clear why that caused the Kaikohe substation to shut down, cutting power to more than half the district.
The northern part of the district, including Doubtless Bay, Kaitaia, the Aupouri Peninsula and North Hokianga, still has power, in an apparent re-run of last week's outage.
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