City mayors power up for action

An electricity generator outside the electrical engineers' conference venue yesterday. Picture / Brett Phibbs

Fed-up Auckland mayors are calling on the Government to tighten its grip on national electricity grid operator Transpower to safeguard supplies to their region and the rest of New Zealand.

The Auckland Mayoral Forum wants Transpower and the Electricity Commission turned into a single department to ensure direct control of supplies, which were cut to 700,000 people during Monday's blackout.

"We have no faith that Transpower can guarantee supply and we believe its planning decisions have been poor," Manukau Mayor Sir Barry Curtis said last night.

"We were shocked at the revelation that the failure of one simple shackle caused the blackout. The entire system has been hanging by a thread and that is not acceptable," Sir Barry said.

"The Government needs to take control to ensure a guaranteed supply of electricity and to ensure accountability in this vital area."

The mayoral blast followed confirmation by Transpower that the failure of a D-shaped shackle triggered the blackout.

Transpower chief executive Ralph Craven told an electrical engineers' conference in Auckland yesterday that maintenance records indicated appropriate equipment inspection and assessment had been carried out.

He said records also showed adequate strength remained in broken earthwiring and associated fittings, but metallurgical tests were being conducted "to determine failure mode".

He refrained outside the conference from commenting in greater detail, saying he did not want to influence an inquiry by independent engineering experts due to report by the end of next week to Energy Minister David Parker.

Leading electricity consultant Bryan Leyland warned against becoming too fixated with the failure of a single piece of equipment, saying: "If it wasn't the shackle it may have been something else."

He told the conference that Monday's chaos was the predictable result of leaving most of Auckland reliant on a single 220,000-volt supply line carrying electricity through Transpower's gateway Otahuhu substation to Penrose.

"We should have two independent supplies - we have got to fix it quick."

Mr Craven, whose organisation is considering various options for duplicating the link in association with its controversial plan to run a 400,000-volt line from the central North Island to Auckland, agreed and pointed to big proposed injections in capital investment.

But Mr Leyland reminded the Weekend Herald that he had been warning about such a failure since the late 1990s, and said New Zealand was out of step with an international standard requiring all loads of 350-megawatts or more to be carried over separate lines.

Aucklanders were not the only victims of the Otahuhu failure.

The Marsden Pt oil refinery disclosed yesterday that it lost $1.4 million from a voltage dip caused by the failure, even though lines carrying supplies to Northland were not disabled during the crisis.

NZ Refining Company chief executive Thomas Zengerly said the dip knocked out his main production units. The supply pipeline to Auckland was also disabled.

Mr Zengerly said he had written to local network company Northpower seeking an explanation, and sent a copy to Transpower.

Transpower spokeswoman Cynthia Brophy denied there had been any loss of supply to Northland from the Auckland failure.

"All I can confirm is that we did deliver continuous supply through the event to the refinery," she said.

Northpower, which relays electricity from the national grid to Marsden Pt, said the dip in voltage was definitely caused by the Auckland failure.

Network services manager Calvin Whaley said this did not mean Transpower's statement was technically incorrect, as electricity remained available from the grid to Northland, but there was nothing his company could have done to prevent the refinery being knocked out.