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!


CAPEX savings


Strain conversions installed


KM of conductors pulled

Our Team Says

It has been an amazing opportunity to lead the design input for such a major project for Transpower. With the last outage complete after 4 years of construction and the project delivered on time and under budget.

Helen Gilbert

Transmission Lines Technical Director - Beca

Our Client Says

In summary the relationship between the Beca design team and the project delivery team is very strong, which is proving to be a big part of the project’s success so far. I look forward to working with Beca on future works and recommend them for any Transpower project design work.

Jon Mason

Project Delivery Manager - Transpower NZ

Our People

Helen Gilbert

Technical Director - Transmission Line Engineering

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Mark Jacob

Renewables Lead and Senior Principal - Power

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