Transpower says upgrading the Cook Strait electricity cable would come at a very small cost to consumers

It's consulting on a 1.4 billion dollar proposal- to upgrade existing cables and allow for building a fourth.

CEO James Kilty says the plan is to get another 40 years of stable electricity.

He says because costs will be paid for over that 40 years, prices won't surge.

Kilty says by the time it's spread out over every connection and all that time - it will mean just a few more dollars a year.