The first of New Zealand's three big electricity transmission projects was formally commissioned by the Prime Minister on Thursday.
It involves 186km of new cables from Whakamaru in South Waikato to Auckland, along with new substations in South Auckland.
The scheme attracted big protests when it was first proposed but was defended as vital by industry. It began transmitting electricity at the end of October this year.
The second big project will upgrade the link between the Benmore Dam and the North Island by way of the Cook Strait cable.
This will be unveiled in 2013, ahead of a third project taking electricity to Northland by way of a cable strung under the Auckland Harbour Bridge and a duct along the North Shore busway.
The schemes are costing billions of dollars and are being developed after delays dating back at least 30 years.