Entrust, formerly named Auckland Energy Consumer Trust, owns around three quarters of its shares, and had full ownership until 2005.

All electricity was generated locally until 1925 when the transmission line from Horahora Power Station to Penrose substation was commissioned.

The AECT was established, along with 29 other energy trusts throughout the country, to ensure that the power lines remained in the control of electricity consumers.

When incorporated, Mercury Energy Limited owned the distribution business in Auckland, Manukau and Papakura, and also retailed electricity to customers connected to the network and elsewhere.

On every measure, including efficiency and what was best for energy consumers in the Trust area, the NZIER concluded that the current setup is the best option.

[6] Vector owns and operates the electricity sub-transmission and distribution networks across the majority of the Auckland Region, from Wellsford in the north to central Papakura in the south, and over the Tamaki Strait to Waiheke Island.

[8] In the year to 31 March 2022, the Vector distribution network had a normalised System Average Interruption Duration Index (SAIDI) of 40.5 planned minutes plus 92.4 unplanned minutes and a normalised System Average Interruption Frequency Index (SAIFI) of 0.27 for planned outages, and 1.05 for unplanned outages.