The planning and design of electricity distribution networks can be divided into three areas. Strategic or long-term planning deals with future major investments and the main network configurations. Network planning or design covers individual investments in the near future while construction design includes the structural design of each network component taking account of the various materials available. The object of this chapter is to introduce those factors which should be taken into account when designing electricity distribution systems. The emphasis will be on general planning guidelines. Later chapters are devoted to more detailed considerations of technical and economic aspects, and specific engineering topics.