This is originated from the Department of Eizan Electric Railway of Kyoto Dento, to which the current Eizan Main Line belonged; thus the name Eiden became commonly used for the Eizan Main Line and the Kurama Line even after the lines came to be owned by the Keifuku Electric Railroad.
ただし、この呼び方は現在の叡山本線が京都電燈の叡山電鉄部であったことに由来し、京福電気鉄道となったあとも、叡山本線・鞍馬線の総称として一般に使われていた。