In powerline communications the signal transmission characteristics of the power line carrier are very significant. This paper presents part of the research work done on the development of an integrated Energy Consumption Management System based on powerline communications. Field test results, concerning signal transmission characteristics on power lines in pilot installations are reported. The well known EMTP is used for the simulation of the transmission path. Simulation results, obtained for the no-load and for the full load cases and after the implementation of carrier wave traps, are compared to the actual measurements from field tests, showing satisfactory agreement. The influence of line length and of line terminations is also investigated for both underground cables and overhead distribution lines.