A forklift driver has been stood down following a major power outage which affected more than a quarter of a million people in Auckland and Northland at peak time on Friday morning.
Both Energy Minister Gerry Brownlee and Transpower's chair Wayne Brown say it shows the need for a second high voltage line in the region.
Transpower says a forklift carrying a container hit the Otahuhu to Henderson line at about 8am while the alternative line was out for maintenance.
Electricity was cut to 280,000 customers in Northland, West Auckland, Rodney and North Shore, with Transpower's chief executive officer Patrick Strange saying the driver is lucky to be alive.
Power was restored to most Auckland customers by 10.30am and Northland by 1pm.
Mr Brownlee says planning and preparation work for the second transmission line is now underway, after years of delays.
"What we have done is approved a very, very ambitious and extensive grid upgrade programme from Transpower. It runs into close to a billion dollars, and we just want them to get on with that work and get it done as quickly and speedily as possible."
Approved only recently
Mr Brown says Transpower applied three years ago to upgrade transmission through Auckland but was turned down by the Electricity Commission. It obtained approval only recently on appeal.
Mr Brown, who is also mayor of the Far North district, says there is no fail-safe transmission system but diversity of supply gives more reliability.
Dr Strange says hundreds of millions of dollars worth of work is underway across the Auckland region to ensure power can't be disrupted in the same way.
But he says it will be another four years before the risk to power supply for Auckland and Northland is removed.
"There's a lot of design going on, it's on target for 2013 or 14, and that'll complete a transmission ring around Auckland. That way you can cut any part of the ring, and you don't interrupt supply."
The driver's boss Neil Reive, from Specialised Container Services, told Checkpoint while it is physically possible for some of its machines to touch the power lines, the company has procedures in place to prevent such incidents.
He says the driver is recuperating at home and will be interviewed by the company on Monday.
Fuel supplies under threat
The head of Northland's biggest electricity consumer, the Marsden Point oil refinery, says the outage was entirely predictable.
The refinery was brought to a standstill but as a priority industry, it had power restored by 9am.
NZ Refining Company chief executive Ken Rivers says it lost hundreds of thousands of dollars in revenue due to the outage.
However, he says the wider issue is that fuel supplies to Auckland could have been totally disrupted.
Mr Rivers says the problem could and should have been avoided with the creation of a robust electrical supply to Northland years ago.
The refinery operates 24 hours a day and depends on a continuous power supply.
It said earlier it will take some time to restart all the processes and find out how much product was lost.
Whangarei District Council chief executive officer Jude Thompson says the outage was bad news for local businesses, and shows just how vulnerable the national grid is.
She says the project to install a second supply route to Auckland and Northland needs to be made a priority.
Battle with councils
Transpower says it has battled for years to try to stop councils allowing building below high voltage lines.
Dr Strange says commercial activity being allowed under power lines has long been a problem for it.
He says the issue is compounded by the fact there is no legislation to support Transpower's calls to have it banned.