Adequate use electric power is a economic, social and even cultural demand today. The first task to achieve this is to measure current consumption to know, with concrete and real data, what are the activities, hours or machines that the greatest influence on energy homes performance, buildings or factories. The actual work present the entire sequence of activities that were developed are shown, finally, to the design and implementation a hardware-software device that could measure the electric power consumption of three-phase loads up to 220 volts and 100 amps for the fundamental frequency of 60 Hz. After of its implementation, the prototype was probed with resistive, inductive and capacitive loads and its results was compared with industrial equipments delivering errors between 1% and 2%, sometimes less. With this instument the institution had a take one first step about energy measurements which will serve how to guide to continue to final objetic, a certificate device.