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Insurers have given Transpower the go ahead to restore part of the inter-island link before winter.

Transpower announced yesterday half of Pole 1 will be available for service at times of peak demand during winter should it be needed. Power would only run northward.

Pole 1 - a massive collection of mercury-filled valves, transformers and oil reservoirs at either end of the inter-island power link - was taken out of service last September out of fear it could fail.

Transpower chief executive Patrick Strange said returning half of Pole 1 to service would provide greater confidence in meeting peak demand this winter. "By running the half pole in a northwards direction, we put less stress on the equipment but can achieve a high rate of performance; close to the same performance we would have achieved if the entire Pole 1 was in use. Our insurers have also reinsured the equipment and are comfortable with its new mode of operation."

The National Winter Group report last month said the power system should manage without Pole 1 this coming winter.

Transpower says a complete $650 million to $700 million replacement option of Pole 1 was the best long-term solution, and was doing economic analysis on market benefits to submit to the Electricity Commission for approval in May.

It would take at least four years to install the new equipment located at Benmore in the South Island and Haywards Hill in the Hutt Valley.

The other half of the Pole 1 equipment will be removed from service.