Regular operation with electric locomotives was introduced on 25 November 1944. To begin with, Class 64 railcars were used. NSB had originally planned to use electric multiple units, but changed the plans during the war and instead decided to use locomotives and cars. The Class 64 trains remained in service on the Flåm Line until May 1947. They were normally used on the Hardanger Line, but were regularly taken back into use on the Flåm Line when the traffic was at its lowest.