Last updated: 05 Aug 2026
What are we doing?
We need to continually operate, maintain and develop Aotearoa's electricity transmission network to ensure we meet the growing electricity needs of New Zealanders now and into the future.
We have identified that two sections of the 220 kV duplex double circuit Huntly–Ōtāhuhu A (HLY–OTA–A) line will soon need replacing due to corrosion. This line is a critical part of the upper North Island system, connecting Auckland and Northland's electricity networks to generation from Huntly and the south.
This line provides several critical benefits to Aotearoa New Zealand, including:
- Reduced electricity generation costs by allowing greater utilisation of lower cost generation that can be transferred into Auckland and Northland's networks.
- Improved security of electricity supply during peak periods, which allows more power to flow into Auckland with lower AC losses.
- Supplies the Bombay, Drury, and Takanini substations.
- Greater competition in the electricity market.
Why are we proposing this?
These conductors are nearing the end of their life due to corrosion. Over time, wear and environmental exposure have degraded the wires, reducing their reliability. A conductor failure may cause it to fall, risking property damage and public safety. This would also lead to an unplanned outage of one or both circuits on the line, restricting power flow into Auckland and Northland.
Replacing these sections will ensure the continued safe and efficient operation of this critical transmission line, which supports electricity supply into Auckland and Northland.
What is happening next?
Earlier this year, we invited feedback from mana whenua, local businesses and communities, and all other interested stakeholders to help shape and inform our plans. We have now published a summary of this feedback, along with our response which you can read here.
We will now prepare a proposal for the Commerce Commission to approve an increase in our base capex allowance to account for Stage 1 of this mahi. If you have any queries, please contact us at [email protected].
To view our consultation documents and give feedback, please click here.