Vandalism to machinery ahead of a day-long power cut for maintenance on Kaitaia's sole high-voltage line caused delays in restoring power and ''extreme frustration'' for Top Energy staff.

The outage was scheduled to last from 8am to 5pm on Sunday and affected North Hokianga, Kaitaia, Aupouri Peninsula and Doubtless Bay. Back-up diesel generators, however, kept the power on in central Kaitaia and much of Doubtless Bay.

Top Energy chief executive Russell Shaw said the discovery of damage to a digger and a ute at the company's Fairburn site, east of Kaitaia, was a bad start for crews who had tough deadlines to meet.

Vandalism, included smashed windows on this digger, delayed the restoration of power in the far North on Sunday. Photo / Top Energy
Vandalism, included smashed windows on this digger, delayed the restoration of power in the far North on Sunday. Photo / Top Energy

"We know the inconvenience outages cause. It is extremely frustrating to have our work impeded by such a senseless act," he said.

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The vandalism is thought to have prolonged the power outage by at least 30 minutes.

The good news for Far North residents, however, was that Sunday's planned power cut could be the last full-day outage required for annual maintenance on Kaitaia's single 110kV line.

The company is applying for resource consent for a 16MW Kaitaia-based, diesel-powered generation farm that could supply all 10,000 customers in the top half of the Far North during planned and unplanned outages.

With back-up generation already in place in Taipa and Kaitaia Sunday's outage had been limited to 4850 customers instead of 10,000.

The plan would be particularly useful as new health and safety regulations meant the company could no longer carry out live line work.

Top Energy's original plan for securing Kaitaia's power supply was to build a second 110kV line but that had been delayed by legal challenges by landowners.

"Diesel generation is becoming, through necessity, a key network management strategy to keep the power on," Shaw said.

The company was also exploring the viability of micro-distribution networks such as solar panels, batteries and other localised generation for more remote locations.

The work carried out on Sunday included insulator and cross-arm maintenance at the Takahue Saddle. With no vehicle access one of the four crews had to walk almost an hour from the end of an ATV track.

Three other teams installed automated switching devices allowing better remote control and isolation of the network on the remote South Rd feeder.

Kaitaia police are investigating the vandalism incident.