The good results of the experiments with, and then regular use of, the three-phase AC traction system, had, by 1912, induced the FS to order 45 locomotives of
Class E.550 and 16 of Class
E.330. The Material and Traction Service of FS now decided to consider the possibility of breaking the monopoly of the Italian Westinghouse Company (
Società Italiana Westinghouse) with the acquisition of two new classes of locomotives for passenger trains, the
E.331 and the E.332. In the spring of 1913, FS prepared the design of the mechanical part to be used for both classes and, after long private negotiations, entrusted an order for the construction of 18 locomotives to the company
Costruzioni Meccaniche di Saronno. The order was divided into two. The first, dated 14 December 1913, was for 6 machines to be built according to the design of the mechanical part prepared by the FS and with the electrical part designed and built by
Ateliers de Construction Oerlikon of Oerlikon, Zurich, which gave rise to the Class E.332. The second, dated early in 1914, was for 12 machines with an E (0-10-0) wheel arrangement, intended for the haulage of freight trains, which would have constituted a new Class 051 (E.551 according to the classification of 1914). The latter, however, were not built because of the termination of the contract, which took place in the spring of 1914 for unknown reasons. Together with the Class E331, the Class E.332 formed the last chapter in the collaboration between the FS and Swiss industry in the field of three-phase electric traction. ==Numbering==