As referred to the safety of people, the metallic fence of a substation is an object of special care. The substation fence is subject to a potential rise as well as to direct contact with people and animals, which is a hazardous situation. The connection of the fence to the substations grounding grid, the sectioning of the fence through isolated parts and the design of a specific fence grounding system are then necessary items for a well-designed project. This paper presents the procedure for calculating the potential rise in a metallic fence, also a report of good fence designing practices, verifying such procedure with an example from the literature.