Greenlight for $1.1 billion Cook Strait power cable replacement

Transpower gains Commerce Commission's approval for $1.1 billion upgrade of Cook Strait cables

Four new cables will renew link and boost capacity

Decision means new cables will be ready by 2030s when needed

Future of existing undersea cables up in the air

The grid operator needed the regulator's permission to go ahead with replace the ageing High Voltage Direct Current electricity link between the North and South Islands.

"We appreciate the Commission's timely consideration of this major capex proposal, with undersea electricity cables in high demand globally as many countries electrify," Transpower chief executive James Kilty said.

"Having this decision now, with a good lead-in time, means we will be able to confirm a contract with the manufacturer of the new cables in time for them to be delivered and installed in the early 2030s when replacement is due."

The approved project involves laying four new cables under Cook Strait - both to renew the existing link but also boost capacity, as well as replacing the cable termination stations on either side.

Transpower said an application for a second stage of the project - an IT system to control the cables' operation - would go to the Commerce Commission at the end of this year.

The grid operator said it had yet to decide what to do with the existing undersea cables and would weigh the effects of leaving them with the cost of removing them.

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