 The first three locomotives were delivered to the Rjukan Line along with two smaller units, RjB 4 and 5 (which were given the designation El 6 by NSB).El 7 is exactly two El 6; it has two transformers, four motors instead of two, Bo'Bo' instead of Bo axle arrangement, two pantographs, the same speed, and could haul twice the load.The locomotives cost NOK 52,090 in 1911.