[2] In this heavily industrialized area of the country with steep grades, the railway would pull heavy freight trains along the North-East line using SNCF 150.X steam locos, often requiring pusher locomotives to help move the trains along.

An experimental program was begun with four similar locomotive designs, one from each maker of electrical equipment, to find the best system.

Investigating the electrification of the Lille – Thionville line, the CC 14000 were part of an order for 85 electric locomotives in 1952, each using a different system: five BB 12000 in a mono-continuous format with ignitron rectifiers, fifteen BB 13000 with direct motors, twenty four-phase CC 14000 and sixty-five CC 14100 with single phase-continuous rotating units.

As a result, the success of this trial led the SNCF to electrify its remaining lines, decided as being both economical and future-friendly.

The 25 kV powers the primary transformer (located in lower center of the locomotive), reducing the current to 1,100 V which is then directed to a frequency converter which varies the current directed to the traction motors from 0 to 135 Hz.