Electricity was mandatory for the operation of the Marathon construction site. The only solution for the Ulen &Company was to produce electricity on its own. The wagons movement, the operation of the stone crusher machine and of the concrete mixer, the tunnel ventilation, the lighting of the buildings of the settlement, and many other aspects of the worksite needed electricity in order to function. The company chose to locate its power station in the Kastri area where four 330 hp Krupp diesel engines were installed. Kastri was selected since it was the closest point to Boyati connected to it by an asphalt road which was important for the engines’ oil supply and had plenty of springs, a vital element for the engines’ cooling off. Even though the Krupp diesel engines were not cheap, it was the best choice because this kind of machines had already been successfully operated in Greece, a fact that Ulen &Company evaluated positively. The power station in Kastri began to operate in June 1927, allowing the acceleration of the works on the dam and the electrification of the settlement. This was extremely important, given that the entire country was not supplied with electrical power until 1975.