Transmission
New Zealand's national electricity transmission grid is important to connect its generating facilities to its demand centres, which are often in excess of 150 km (93 mi) in distance from each other. The national grid is owned, operated, and maintained by state-owned enterprise Transpower New Zealand Limited. In total, the national grid contains 11,803 kilometres (7,334 mi) of high-voltage lines and 178 substations.
The first major transmission lines came about in 1913-14, connecting the Horahora hydro station to Waikino, and Coleridge hydro station with Addington in Christchurch. The interwar years saw the first major construction of a national network of 110 kV connecting towns and cities to hydroelectric schemes. By 1940, the transmission network stretched from Whangarei to Wellington in the North Island, and Christchurch to Greymouth and Invercargill in the South Island. Nelson and Marlborough were the last regions to join the national grid in 1955. The 220 kV network began in the early 1950s, connecting Auckland to Wellington, and Christchurch to Roxburgh. The two islands were joined together by the HVDC Inter-Island link in 1965.
Read more about this topic: Electricity Sector In New Zealand