Railway electrification in New Zealand

Railway electrification was initially adopted by the New Zealand Railways in New Zealand for long tunnels; the Otira Tunnel, the Lyttelton Rail Tunnel and the two Tawa Tunnels of the Tawa Flat Deviation. Electrification of Wellington suburban services started with the Johnsonville Line and Kapiti Line out of Wellington from the 1930s. Auckland suburban services were electrified in 2014–15. Electrification of long distance services on the North Island Main Trunk (NIMT) dates from 1986, although Kiwirail is now considering diesel operation of the NIMT. New long tunnels e.g. the Rimutaka Tunnel and the Kaimai Tunnel were operated by diesels, and the Otira and Lyttelton Tunnels have converted to diesel operation.

From 1908 to 1953 there was an electrified mine railway from the on the West Coast of the South Island.

Earlier NZR electrified routes from 1923 to the 1940s operated at 1500V DC, but the NIMT (1986) and Auckland suburban services (from 2014) use 25 kV AC; all with overhead catenary supply. The use of 16 kV AC (at 16.7 Hz) for the NIMT was proposed in 1950.

The railway was, in 1908, New Zealand’s first electric railway. It carried coal from the Westport-Stockton Coal Companies mine to the NZR railhead at Ngakawau on the West Coast of the South Island from 1908 to 1953, when it was replaced by an aerial cableway. The line was 10.5 km long, with 2.4 km in two long tunnels. The system used 275 v DC from a low overhead line via trolley poles, and 915 mm gauge track. The seven locos were of low built “mine” type.

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