To test the optimum technology for electrification with 25,000 V and 50 Hz, the SNCF had four different types of electric locomotives built by different manufacturers. Testing took place on the line between Lille and Thionville, where heavy freight trains had to be moved over steep gradients. In addition to the BB 12000, BB 13000 and CC 14100, 20 CC 14000 were built with three-phase traction motors and a rotating converter. Although the electrical operation was a success in itself, the complexity of the CC 14000's technology meant it could not stand the test. 