[3] The Government-General of Korea began working on a national electric power policy in November 1926, and the resulting plan was completed in December 1931.

[4] The Railway Bureau began implementation of the plan in 1938,[5] and subsequently placed orders with Mitsubishi, Toshiba and Hitachi for 26 electric locomotives.

[10] As the Korean War caused the destruction of the electrification of North Korea's rail lines, they sat disused until 1956, when they were reclassified Chŏngidu (전기두) class and numbered 전기두1 through 전기두4.

They were then refurbished at the engine shops at Yangdŏk for use on the Yangdŏk-Ch'ŏnsŏng section of the P'yŏngra Line, which had been electrified in 1956 as the first stage of North Korea's electrification plans.

[11] Originally painted brown, they were repainted in 1958–1959 in the light blue over dark green livery to match the scheme that was made standard with the introduction of the Red Flag 1 class electric locomotives.