Already by the mid-1910s FNM was considering introducing electric traction to handle heavy commuter traffic, especially on the Milano-Saronno and Milano-Meda line. At the time there was no single idea on the best system to adopt.
The first examples of electric traction in Italy were mainly three-phase, deemed unsuitable and in certain aspects already becoming obsolete, while others experimented with direct and alternating current at different voltages on both the overhead contact wire and on the third rail.
It was not until the mid-1920s, following the hiatus of the Great War, that a solution was agreed upon. The FNM engineers and managers were guided by the idea of adopting a service carried out with consists of electric diesel railcars and pilot trailers for suburban trains and with locomotives for standard car trains and goods trains.
Following a call for tenders from the main companies in the sector, plans by Tecnomasio Italiano Brown Boveri (TIBB) were chosen for the electric railcars and by Compagnia Generale di Elettricità (CGE) for the electric locomotives. The system proposed by TIBB entailed a 3,000 V direct current power supply through overhead contact wire. This system was the same as that being worked on by the FS on its trial Foggio-Benevento section, and was also already in use in certain parts of North America.
The first fleet of electric trains (32 units of rolling stock consisting of E 700 engines and E 800 control trailers) was commissioned to the Officine Meccaniche (OM)-TIBB for the engines and the Officine Elettro-Ferroviarie Tallero (OEFT)-TIBB for the control trailers. The trailers were later gradually converted into E 700, 730, and 740 (first series) electric railcars and replaced by lighter pilot cars.
Out of the three plans put forward (by CEMSA, OM and TIBB), the engines were commissioned to the OM-CGE consortium. The first 4 engines in the E 600 class were delivered in 1928. Shortly after, another 2 E 600s were ordered, which were delivered in 1929.
While the rolling stock was being ordered and built, the Milano-Saronno and Milano-Meda lines were being equipped with piling, overhead contact wire and related subsystems. A brand-new locomotive depot/workshop was built at Novate Milanese for the electric material and a transformer and rectifier electric substation was built inside the depot. The first years of operation proved to be a success.
In the 1930s, with the expansion of electrification to steeper lines such as the Saronno-Como, it was decided to overcome the limited power of the E 700s by coupling them with Piaggio-built pilot trailers, which were lighter than the original E 800s; these cars were built with electro-welded stainless steel plates. These were also equipped with driving cabs and featured first and second class compartments separated by a toilet. This arrangement was later to determine, both during and immediately after World War II, the basic model for FNM electric trains.
In 1942 and again in 1948, on the basis of the experience gained from the Piaggio trailers, the original E 800 trailers were replaced by 12 EAC 810 and 6 EC 830 trailers, vehicles which would later be the prototype for all rolling stock built by Breda in Sesto San Giovanni in the 1950s (classes 800, 820 and 840). The E 800 trailers, given their very robust structure, were all therefore converted into electric railcars.
In 1949, a further 4 E 610 electric locomotives were added to the fleet. They were also of a modern design, with a fully electro-welded self-supporting body, similar to the design of the FS E 424 locomotives.
Lastly, from 1953 to 1957, Breda supplied Ferrovie Nord with around twenty class 740 electric railcars. These engines, whose structure was standardised to that already established with the 810 and 830 cars of the 1940s, have a self-supporting electro-welded body with tubular frame. Although it introduced a number of innovations, it was nonetheless fully compatible with the earlier generation of electric rolling stock. Their power was similar to that of the first series achieved with the motorisation of some of the old E 800 trailers from 1928-30. Commonwealth-type bogies are common to all of the previous vehicles.