The locomotives were part of an electrification project undertaken by the N&W to improve traffic conditions on the Elkhorn grade in its Bluefield Division.

In the early twentieth century the Bluefield Division of the Norfolk and Western Railway featured a forbidding two percent average grade.

Multiple 2-6-6-2 Class Z1 "Mallet" articulated steam locomotives labored hauling 3,000-short-ton (2,700 t) coal trains up and down the grade.

According to William D. Middleton, Gibbs & Hill believed that the "ruggedness and simplicity, high output, uniform torque, and adaptability" of three-phase made it a superior choice to single-phase AC or DC for the mountainous Elkhorn area.

In June 1915, with electric operation only partially implemented, this rose to 397 trains averaging 3,054 short tons (2,771 t), a 60 percent increase.