6.25kV / 25kV dual AC class 302 EMU at Upminster. 1984.
302 226 one of the original 112 4-car dual voltage AC EMU's built for the LT&S (London Tilbury & Southend) 6.25kV electrification is seen at Upminster forming train 2U11 the 13.26 Shoeburyness to London Fenchurch Street. The LT&S was electrified from 1959 onwards at 6.25kv AC rather than 25kV in an effort to reduce costs with expensive infrastructure alterations but the units were designed to run into London Liverpool Street on the GE lines as well as Fenchurch Street. The former GE (Great Eastern) terminus was still using the older 6.25kv AC supply on the inner suburban routes but further out supply was already at 25kV AC so any new EMU's had to be dual power. Reliability problems with the voltage changeover equipment and inadequacy of the weaker supply eventually saw BR convert the remaining 6.25kv lines to 25kv AC as standard from 1975 onward but parts of the LT&S were the last to change. This is why the newer class 312's were delivered as two sub classes 312/0 (sets 701-726) for the GN (25kv only) and 312/1 (sets 781-799) for the GE (6.25/25kv dual). The 315 EMU's built in 1980 were the first new trains to run on the GE that were specified as 25kv AC only.
6.25kV / 25kV dual AC class 302 EMU at Upminster. 1984.
302 226 one of the original 112 4-car dual voltage AC EMU's built for the LT&S (London Tilbury & Southend) 6.25kV electrification is seen at Upminster forming train 2U11 the 13.26 Shoeburyness to London Fenchurch Street. The LT&S was electrified from 1959 onwards at 6.25kv AC rather than 25kV in an effort to reduce costs with expensive infrastructure alterations but the units were designed to run into London Liverpool Street on the GE lines as well as Fenchurch Street. The former GE (Great Eastern) terminus was still using the older 6.25kv AC supply on the inner suburban routes but further out supply was already at 25kV AC so any new EMU's had to be dual power. Reliability problems with the voltage changeover equipment and inadequacy of the weaker supply eventually saw BR convert the remaining 6.25kv lines to 25kv AC as standard from 1975 onward but parts of the LT&S were the last to change. This is why the newer class 312's were delivered as two sub classes 312/0 (sets 701-726) for the GN (25kv only) and 312/1 (sets 781-799) for the GE (6.25/25kv dual). The 315 EMU's built in 1980 were the first new trains to run on the GE that were specified as 25kv AC only.