This document provides an example calculation of the electrical load of a building with the following specifications: it has 5 floors with 3 flats on each floor, each flat has a 240V single phase supply and 20 wiring points, there is one 15HP lift motor and two 5HP machines, the building receives a 415V 3-phase supply. The summary calculates: 1) The total electrical load is 52.137KW 2) The main switch size is 100A 3) The main cable is 25mm sq copper cable 4) Each flat has 5 sub-circuits