Important aspects of electricity system planning are overall yearly electricity consumption and information about variations in consumption. These variations will influence the capacity that has to be installed, as well as the type and quantity of fuel that will be used. Using only economic, socio-economic, technical and meteorological indicators, we have developed a model that can predict the hourly load shape. This model is based on a division of the total electricity-consumption into 60 economic sectors and electrical appliances. For each of these sectors, a load shape is formed. Summation over sectors then gives the total hourly electricity consumption pattern. To test this model, the hour-to-hour load shape of the Dutch public grid for 1980 was formulated and compared with the actual load shape. The root-mean-square difference between the estimated and actual load shapes is 5% of the mean hourly load. The accuracy of the estimated maximum load for every week is of the same magnitude as that used for electricity-supply system planning over the short term. We conclude that our model can be used for long-term load shape forecasting.