Lightning leaves $200k bill

Lightning damaged this transformer at Tinopai.

Lines company Northpower fielded a staggering 1400 fault calls over just two days during recent lightning strikes that cost the company about $200,000 in repairs and maintenance.

Northland bore the brunt of nearly 8000 lightning strikes that hit the upper North Island on October 29 and 30, causing power outages and surface flooding throughout the region.

The $200,000 cost follows about $900,000 Northpower spent repairing the 800-900 faults during the July storm from an annual repair budget of $1.46 million.

An active trough moving in a northeasterly direction from the South Island was responsible for October's thunderstorms, high-intensity rainfall and strong winds.

Northpower network engineering manager Russell Watson said about 30 pole-mounted transformers from the 5800 throughout Whangarei and Kaipara were replaced due to lightning damage. Usually that many transformers were replaced in a year, he said.

"This was one of the most severe lightning events that I can remember as its effect was felt over most of our network area as well as the significant number of faults, around 500 faults were attended on October 29 and 30," he said.

Mr Watson said a major power outage was in west of Whangarei and further north after a lightning strike at Northpower's Kamo substation on October 29 caused a circuit-breaker feed to fail, resulting in about 8000 customers losing electricity briefly. Dargaville and Maungaturoto were the worst affected areas, he said.

"I've been here [Northpower] 31 years and this was a severe lightning event just from the sheer number of strikes and a large spread over a large area. Normally we wouldn't have expected this number [of outages] at the top end. Lightning can be very fickle but it's usually rain and wind that give us more trouble like they did in July," Mr Watson said.

He said lines' crews were in storm mode by 7.30am on October 29 and set up a "storm room", answering fault calls and entering jobs into their system.

The Far North got off relatively lightly and Top Energy spokesman Peter Heath said the cost of repairs during and after the lightning strikes was less than $20,000.

Top Energy's yearly budget for faults is $1.3 million but during the July storm, it estimated repairs to hundreds of faults on its network would cost about $1.5 million. Damage to its network in July was the worst since Cyclone Bola in March 1988.