Sydney Harbour railway electricity tunnel is heritage-listed electricity infrastructure running under Sydney Harbour between Birchgrove and Greenwich, Sydney, New South Wales, Australia. It is also known as Balmain to Greenwich Electric Cable Tunnel. It was added to the New South Wales State Heritage Register on 2 April 1999. History The tunnel was built between Long Noise Point, Birchgrove, and Manns Point, Greenwich, from 1913 to 1926 to carry submarine electricity cables for the electric tramway system on the north side of the Harbour as submarine cables laid across the bed of the harbour had suffered damage from ships and their anchors. It was one of Australia's major engineering feats at the time of construction, and was the first tunnel completed under Sydney Harbour. The first tram route on the northern side of the harbour was established in September 1893 and stretched between Falcon Street, North Sydney and Spit Road. It was extended to Mosman Bay in 1896. Steam trams already ran south of the harbour and by 1904 the conversion of this network to electricity was well underway. The railway and tramway power stations at White Bay and Ultimo were increasing their capacity and a new electric substation was constructed at North Sydney to serve the expanding tramway system. Cables were laid across the bed of the Harbour to feed the power from White Bay to North Sydney. The obvious location was the shortest distance which was between Long Nose Point and Manns Point at Greenwich. By 1912 the expansion of the tramway network and need for more power and communication meant that more cables were required. To protect these cables it was decided to construct a tunnel to house them. Work commenced in October 1913 at the Long Nose Point end, at the corner of Louisa Road and Numa Street. The steam railway service from Hornsby to St Leonards was established in 1890 and extended to Milsons Point in 1893. This service was converted to electricity in 1927, the year after the completion of the tunnel. First tunnel The tunnel construction job itself was a series of "Homeric battles": The work was started from three points; Long Nose Point, Greenwich, and a shaft at the extreme end of Mann Point, which is a continuation, more or less, of Greenwich. Initially progress was rapid, however some problems were encountered. First of all, the residents of Long Nose Point, in letters