Last updated: 21 Jul 2025
What we are doing?
We need to continually operate, maintain and develop New Zealand's transmission network - the National Grid - to ensure we meet the ongoing electricity needs of New Zealanders.
We have identified that we need to replace the conductor (wire) on the Flatbush to Hūnua section (31km) of the Ōtāhuhu–Whakamaru A and B transmission lines in Auckland due to corrosion. These lines are an important part of the upper North Island transmission network, connecting the Auckland network to generation from the south.
Why we are doing it?
The conductor on this section of line was commissioned in 1952, and after 73 years of service is now nearing the end of its economic life. Corrosion from high levels of salt in the air have led to significant corrosion over its lifetime, and deterioration has reached a point where replacement in the near future is required in order to continue to provide a safe high voltage transmission service.
What happens next?
Following feedback from our recent consultation, we plan to submit a proposal to the Commerce Commission for an increase to base capex allowance to
recover the costs of this project.
More information:
This is the second stage of the Ōtāhuhu–Whakamaru A and B Lines Reconductoring Project. The first stage of this project, replacing the wires from Ōtara to Flatbush, was completed in 2023.
During this project there were no interruptions to power supply, and the effects of the construction were localised to those communities near the line. Transpower worked closely with our affected landowners and communities to ensure we kept disruption to a minimum and they were aware of our work.
Investigation engagement information [ pdf 2.7 MB ]