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Transmission

The grid is owned and operated by Transpower, a state-owned enterprise.

The national transmission grid has approximately 12,000 km of high voltage transmission lines and more than 170 substations. The grid transports electricity from over 50 power stations to connect with distribution networks or major industries at around 200 grid exit points (GXPs) across New Zealand.

Most of the grid operates on alternating current, at different voltages ranging from 50kV up to 220kV. There is also a direct current (HVDC) link for long distance transfer of power between Benmore in the lower South Island and Haywards near Wellington. The HVDC link includes the set of cables running under Cook Strait, and is sometimes informally referred to as the ‘Cook Strait cable'.

Transpower also plans and builds new grid investments. Major grid investments must first be reviewed and approved by the Electricity Authority. Transpower is responsible for all development processes.

The asset value of the grid is over $2.5 billion and is expected to increase by a further $2.5 billion over the next few years as approved grid upgrades are commissioned.

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