In 1899, the Burgdorf Thun Railway had been the first electrified railway line in Switzerland. It was electrified with 750 Volts three-phase AC at 40 Hertz. The first two-axle freight locomotives built in 1899 often still needed the railway's 2-8-0 steam locomotive as helper. So in 1910, electric locomotive No. 3, designated Fc 2x2/2, was put into service. It had a B-B wheel arrangement, each bogie having one traction motor that powered two axles via coupling rods. 

With nearly twice the power of the F 2/2, it could haul 170 tonnes on an incline of 2.5 percent. Pole switching created four sustained speeds between 15.75 and 42 km/h. When drawn by another locomotive, it was approved for 60 km/h. In 1918, a second locomotive was built for the Hasle-Rüegsau-Langnau line that had only 500 hp due to the poorer power supply. Although the second locomotive was prepared for service under 1,500 Volts, all three-phase locomotives of the BTB were retired then the lines were rebuilt to 15,000 Volts single-phase AC.