The final stage of the $3.5 million Ōhakea to Bulls electricity upgrade was carried out during a week in March 2023. 

The work involved installing a steel duct, holding an electricity cable, along the side of the Rangitīkei River Bridge. 

For the work to be carried out safely, traffic management was put in place overnight, between 7pm and 7am week days, with one lane operational. 

The work was carried out overnight to limit disruption over the bridge, which is part of busy State Highway 3. As well as advertising the bridge traffic management via social and local news media, we worked with Waka Kotahi and local stakeholders so that the wider community, particularly the trucking industry, was aware of potential delays on the bridge while work was taking place.

The bridge crossing was the final stage in a three-year project to connect the new Ōhakea substation on the southern side of the Rangitīkei River Bridge and our Bulls substation on the northern side.

$15 million investment

The installation and commissioning of the 33kV underground electricity cable between our Ōhakea and Bulls substations is part of a $15 million investment in our underground network supplying Feilding, Sanson and Bulls townships, including the Royal New Zealand Air Force base at Ōhakea.

The upgraded underground network will provide secure back-up electricity options for the Manawatū and Rangitīkei regions, so we can restore power to those communities’ customers quicker and more safely if there is a power cut.

Why investment was needed

To ensure we could continue to supply the Feilding, Sanson and Bulls' homes and businesses, including the Ōhakea Airforce Base, now and into the future, work was needed to boost electricity capacity in the Rangitīkei-Manawatū region.

The northern region of our Manawatū network area, including most of Palmerston North, is supplied electricity through Transpower’s Bunnythorpe grid exit point (GXP). Our regional underground 33kV cable network then supplies three substations – Feilding, Sanson and Kimbolton. However, there was no high-voltage circuit for back-up supply between Sanson and Bulls, meaning we couldn’t restore supply to customers in the area from another substation if they had an outage.


Added to this, the New Zealand Defence Force had indicated it was embarking on significant upgrades at its Ōhakea airbase, increasing airbase electricity demand to 8MVA. 


To solve these energy supply constraints, we constructed the new 10MVA substation at Ōhakea. Work to install new 33kV switchgear at the Bulls substation is taking place during the 2024 financial year, with the thermal upgrade of a section of the existing 33kV line between Marton and Bulls expected to be completed in the 2025 financial year. When complete, the entire project will provide a connection between Transpower’s Marton and Bunnythorpe GXPs, providing energy back-up to the new Ōhakea substation and Bulls substation, as well as the ability to reduce the load at the Sanson substation and enabling transfer for load off Bunnythorpe GXP to Marton GXP.



Latest project update

Monday, March 06, 2023
The final stage of the $3.5 million Ōhakea to Bulls electricity upgrade will be carried out from 13 March 2023.


2020 and 2021

Construction of a new 33kV/11kV zone substation adjacent to the Ōhakea Royal New Zealand Airforce base.

Installation of new 33kV switchgear at Sanson and Bulls substations.

Thermally upgraded a section of the existing 33kV line between Marton and Bulls.



Construction of a new 33kV underground electricity cable line between the Ōhakea and Bulls substations, to connect to existing 33kV underground cabling between Ōhakea and Sanson substations.


Early 2023

New ducting installed along the side of the Rangitīkei River Bridge to carry the cable across the extensive riverbed, completing the new electricity connection.


2023 to mid-2024

Bulls substation upgrade, including the installation of a new 33kV switchroom and ripple plant.