Downed line in Port Chalmers could have been deadly

A firefighter battles a grass fire among pine trees near a live electric fence through which high voltages ran at times due to a downed power line. Photo / Gregor Richardson

A downed line that sent a high-voltage current down an electric fence on a Port Chalmers property yesterday could have been deadly.

The 33,000-volt Aurora Energy line came down after a cross-arm broke off, sending a potentially lethal current down the fence.

This resulted in two fires on a Blueskin Rd property and scorch marks along the length of the fence.

Firefighters, who were called to the property about 3pm, were at first unaware the fires had been caused by a downed power line.

‎Delta operations manager John Campbell said the line came down because a cross arm had rotted away and the failure was a symptom of an ''aged network''.

There was no risk to the firefighters as protection would have kicked in, cutting power to the line after about a second, he said.

However, he accepted there was a potentially fatal risk should anyone have been standing near the fence when the line came down.

The line came down less than a week after Delta flew a helicopter along it to check for faults.

Mr Campbell said it was possible other cross arms were rotten along the line, which ran from Halfway Bush to Port Chalmers, and this would form part of the investigation into yesterday's fault.

Despite the failure, he stood by Delta and its sister company Aurora's assertion the network was safe.

Whistleblower Richard Healey said he was shocked to learn about the incident.

A fallen line was one of the most dangerous things that could happen on the network as it was the highest voltage line of any owned by Aurora in Dunedin.

It was was clearly an example of a lack of investment in the network, putting people at risk.

The current could have travelled kilometres down the fence and anyone close to it while it was live was at risk of being ''seriously hurt at a minimum''.

''At that voltage you are not talking about getting an electric shock and getting thrown across the room. That's instantly blowing off body parts and almost certain death.''

When Delta was first alerted to the problem, it incorrectly traced it to some trees touching a line in Halfway Bush, he said. This version of events was later backed by Mr Campbell.

When the Otago Daily Times arrived at the scene of the blaze, firefighters had crossed the electric fence and were fighting the fire with a water hose.

The high-voltage line had broken from its crossbar and was swinging in the wind less than 2m above the ground. The line was making contact with the supporting power pole.

Firefighters were overheard ordering all staff to stay away from the fence once the potential danger was realised.

Station officer Cam McLachlan, of Port Chalmers, said a fire 20m by 20m occurred in pine trees on the property. It also caused a small grass fire on a different part of the property.

Firefighters from Port Chalmers, Ravensbourne and the Otago Rural Fire Authority attended.

• This article has been corrected. A previous version incorrectly stated the electric fence was connected to the pole carrying the downed line.

-Additional reporting by Timothy Brown