Trains consisted of electric multiple units powered by third rail electrification. This corresponds to line voltage on the Third Rail network. This avoids the danger of passengers stepping on an electrified third rail. These will continue to be powered by electricity drawn from the third rail. Therefore, an attempt of conversion to third rail would have been pointless. This is the northern boundary of third rail electrification. Another unusual aspect was the configuration of the third rail. Trains draw power from the electric third rail. Others designs collected current from a third rail. In addition, low temperatures resulted in problems with electric current collection from the third rail. The power output is supplied by 750 volt direct current through third rail. Power comes from a top contact covered third rail at 750 V DC. SR decided to electrify their network using the third rail DC system. To assist Siemens in the design of third rail units, 4Vep no. Construction is in progress for a third rail line (Linea 3).