With the increase in electricity demand, new sources of power generation and transmission lines are needed. Thus, because of the need to meet the demand for electricity, transmission lines and substations are increasingly present in urban and local areas near the movement of people. Since electromagnetic fields are a result of the electrical installation, there are rules governing the field exposure levels due to the possibility of causing adverse health effects. The institution which sets the levels of exposure limits is ANEEL (Agência Nacional de Energia Elétrica), with the Normative Resolution nº 398. The analysis of electromagnetic fields can be performed by measurements, analytical calculations, or through computer numerical solutions. This study aims to determine the electromagnetic fields from computer numerical solutions of an output line of a gas-insulated substation, determining the minimum distances for operation and pedestrian traffic.