This paper tries to test an economic explanation of the residential demand for electricity in Colombia (Bogotá and Medellín) during the period 1970-1983. The demand model takes into account aggregation problem brought companies. Instead of aggregate reduced forms corresponding to each consumer class. Three estimation deterministic information about the supply function is available for every time period Although functional forms of the structural model are quite simple, final reduced forms cannot be linearized, thus nonlinear statistically acceptable and conform with the conventional cicroeconomic proposition.