The paper presents replacement of 35 kV equipment because of it is worn out condition, technical obsolescence and hard maintaining ( lack of spare parts). This paper describes process of replacing guide field, transformer field, junction field, measuring field and house transforming field, as a criteria that needs to be fulfill for normal functioning of the whole system. A final calculations of three pole short circuit of 35 kV were performed, also calculations for the selection of the switches, current measuring transformers and voltage measuring transformers. The process of sizeing compounds, guides, considering, rated current of the transformer, thermal stress in short circuit and dinamic stress are also explaind and described. Special attention is pointed at protection from hazards such as high voltage, possibility of a fire etc. The whole project was examinated in detail and tested so that all criteria are fulfilled for quality and secured work system, but most importantly the protection of human lives.