Electrification of the railways began in the 1920s with the building of the Colenso Power Station for the Glencoe to Pietermaritzburg route and the introduction of the South African Class 1E.

Nearly all railways in South Africa use a 3 ft 6 in (1,067 mm) narrow gauge track (Cape gauge). This was selected in the 19th century to reduce the cost of building track across and through the mountains found in several parts of the country. The Gautrain rapid transit railway uses 1,435 mm (4 ft 8 1/2 in) (standard gauge). Ultimately, the hope is that the conversion to standard gauge will also enhance rail's potential as a freight carrier.

Between 50% to 80% of the rail lines in South Africa are electrified. Different voltages are used for different types of trains. Most electrified trains run 3000 V DC (overhead); this is used primarily for commuter lines, and has been in use since the 1920s. During the 1980s, higher voltages (25 kV AC andmuch less frequently50 kV AC (both overhead) have been used for heavy duty lines (also more sleepers per kilometre), primarily in the transport of iron ore.

Class 4E
Nicknamed Green Mambas
Height 3,924 m
Weight 155 487 kg
6 GEC WT80 traction motors
Top speed 97 km/h

Class 10E
Height 4,12 m
Weight 125 000 kg
6 SE-218 traction motors
Top speed 90 km/h

