Pole reinforcement trial

We’re extending the safety and working life of wooden poles across our North Island electricity network by using a new reinforcing technique.

During 2020-21, about 600 wooden poles were reinforced in the Wairarapa region using the technique, with another 150 in Taranaki.

It follows a pole reinforcement trial in Whanganui in early 2020, in partnership with Logsys, where 200 wooden poles were strengthened with strappings and steel trusses, applied using a pneumatic ram.

Asset Engineer poles and towers, Andrew Jarman, says of the 265,000 poles on our network, 36,000 are wooden.

“Many of those 36,000 wooden poles in use across our network are still in good condition. By extending the life of the wooden poles, we can run our network not only safely, but cost-effectively for our customers. The cost of reinforcing is between $1200-1300 per pole as opposed to $4000-7000 for a new concrete pole.”

Reinforcing poles using trusses is not new, however this technique – developed in the United States – is. In the past trusses were bolted to the pole, however drilling the bolt hole often introduced microbes, leading to internal rot and requiring replacement of the pole.

With the trial complete, our Asset Team studied the data and monitored the poles before deciding to adopt this technique to reinforce other wooden poles on our network.

It’s estimated that poles will have up to another 20 years’ service once they’ve been reinforced in this way.

Once the reinforcing is complete, a certification label is attached showing the type of truss used, the date it was installed and other engineering data.

“That information is also recorded in our GIS system, so we have all the latest data at our fingertips.”

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