Strengthening the capacity of New Zealand’s national grid

Existing conductors on the BPE-HAY transmission line were over 40 years old and facing increased wear. This project replaced these conductors with larger, more energy efficient lines that strengthen the capacity and resilience of NZ’s national grid.

Stretching over 130 km across the Hutt Valley in New Zealand’s lower South Island, the Bunnythorpe to Haywards (BPE-HAY) transmission line forms an important spine in the nation’s wider energy grid.

With the decades-old transmission lines requiring replacement, we created a more energy efficient transmission system with added capacity, through installing old conductors and uprating of the two existing transmission lines.

A key objective of this project was to reconductor (replace old transmission lines with new ones) these two lines whilst minimising the capital costs and disruption to the public’s reliable supply of electricity. Given their proximity to salty coastal air, an even higher degree of weather-proofing also needed to be built in.

Collaborating closely as full-service partners with Transpower, we undertook detailed design for the trial of three high-tension, low sag conductors. We also worked closely with Electrix Ltd, in the deployment of a catenary support system (CSS). This enhanced worker safety when installing new conductors over heavily populated areas, road and rail networks and other critical infrastructure.

Throughout the construction period, we also monitored overall works, paying particularly close attention to foundation works, tower erection and wiring.

The end result of our close collaboration is a more efficient, reliable transmission line system that will keep the lights on in the lower North Island for many years to come. The project being completed on time and under budget was an added bonus!