In 1929 the Christchurch to Lyttelton section was electrified in order to reduce smoke in the 2.6 km Heathcote Tunnel. The six Ec class locos were purchased from English Electric exclusively for this work. They worked for more than 40 years until the electric overhead was removed from the section in 1970.
Class leader Ec 7 was transported to Ferrymead in 1972 and stored until 1977 when it was shifted onto the railway tracks. In 1978 part of the Ferrymead line was fitted with overhead cabling (cantenary) and some test runs were done with Ec 7 using the tramway 600V power supply.
Construction of a substation able to supply the railway, tramway and trolley buses was commenced and in November 1988 it was officially opened with trains hauled by Ec 7 on the electrified section of the Railway. Current plans are to complete electrification of the entire main line between the Ferrymead and Moorhouse stations within the next year.
