However, because the extension of the line to the Sanyo area was assumed from the start, the use of 60 Hz throughout the line was decided to simplify the specially high pressure devices required on the train-car side.
しかしながら、当初から山陽方面への延長を構想していたため全線で統一し、車両側の特高圧機器の簡素化を図ったものである。