In recent years there has been a series of documents such as the European Strategy 20-20-20 to address the issue of energy efficiency in various sectors of activity. The objective is to reduce 20% of energy consumption, 20% of GHG emissions (Greenhouse Gases) and 20% of the energy consumed from renewable sources. Public lighting participates with 2.3% in global electricity consumption, so all contributions to the reduction in energy consumption will be relevant. Decision support in the investment analysis on efficient and sustainable street lighting allows a better use of the installed power. Hence, this paper deals with the reduction of losses in cables of a street lighting installation, depending on the luminaire used, presenting both simulation and experimental results. The economic choice of cables losses will allow improving the efficiency of the street lighting in general, providing also an optimal cost/benefit relationship. Moreover, real-time data acquisition systems of the equipment’s consumption can be integrated into a collective awareness system.