Construction work is estimated to begin in next summer and will be completed by 2020.
The upgrade project will add 0.041 cents per kWh to consumers power bills.
Commissioner Stephen Gale said, "The replacement appears to be unavoidable because the lines are in poor condition and doing without them would cost nearly $1b.
"The Transpower proposal includes $10.4m to increase the capacity of the lines."
Gale said the upgrades aims for reduction in transmission losses and improve the ability to use the cheapest mix of generation from the thermal generators in the North Island and the hydro generators in the South Island.
"The benefits of the upgrade will depend on electricity demand growth and on what new generation is built. The Commission has approved the upgrade but expects Transpower to monitor developments and review the project if there are material changes in the expected benefits," Gale said.
Transpower grid development general manager John Clarke said, "These lines are a very important piece of New Zealand’s National Grid as they are responsible for moving power between the North and South Islands across the HVDC link."
Image: New Zealand Commerce Commission approves Transpower’s Bunnythorpe-Haywards power line upgrade. Photo: courtesy of twobee / FreeDigitalPhotos.net.
