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Cable through the Lyttelton Tunnel


In July 2019, we completed a three year programme of upgrades to our network to address reliability and resilience issues with the power supply to Lyttelton, Corsair Bay and Cass Bay community.

The programme addressed historical issues with lengthy power outages due to the sole supply of power to this community being via 11kV lines over the Port Hills which are vulnerable to weather, vegetation and pests.

The installation of a new 11kV electricity cable from our Heathcote zone substation, through the ventilation duct above the Lyttelton Road Tunnel was the final, major network enhancement to provide increased surety of supply to this community. The 2.2km cable connects with Lyttelton’s electricity grid at Orion’s Dublin Street substation, and was switched on at the end of July.

With the 11kV cable installed underground and protected in the tunnel, Orion now has alternatives to keep the power on. The new cable runs in tandem with the existing two 11kV power supply lines over the Port Hills.

Lyttelton Port is an essential lifeline for Canterbury and increasing the resilience of the power supporting it is important for the wider region.

To support future growth in this vital community, the new cable has a power rating of 10 Megawatts, 3 Megawatts greater than the current average demand.

Project Details

Date Completed

5 2019

  • Three separate cables: 3 x single core, continuous cable, with no joints
  • A power rating of 10 Megawatts, 3 Megawatts greater than current average demand which means it is future-proofing the supply – allowing capacity for growth
  • Each cable 2.2 kilometers long, weighing 11T each
  • The cable pull through the tunnel is around 2 kilometers, with extra to take them to the connection points at either end
  • This is the longest 11kV cable pull in Orion’s history
  • Each cable drum is 3.15m diameter x 2m wide, made of steel