The high-voltage overhead lines used to transport electrical energy from production plants to distribution stations constitute a very important link in the chain of providing electrical energy to communities. However, they constitute potential sources of emission of electromagnetic waves whose impacts are harmful to human health (thermal electrical stimulation of tissues and in particular those of the brain causing different forms of cancer) if the safety distance between these lines and users is not respected. In recent years, Benin has experienced, in urban areas crossed by transport lines and particularly among populations living in the vicinity of these lines, an explosion in the rate of people suffering from cancer. This study is carried out not only to check whether the minimum distance according to the voltage levels of these lines is respected in order to ensure the safety of people living in their vicinity but also to develop a standard of minimum distances to be respected. By the numerical simulation method based on Maxwell's equations established in a supposedly empty medium, the Bio-Savart law and the Lorentz transformation, the model of wave intensity as a function of distances, is determined. The results obtained respectively give minimum safety distances of 15 meters, 20 meters and 36 meters for the 63 kV, 161 kV and 330 kV high voltage lines Category B. These distances are, by far, respected by the populations. Furthermore, the results clearly show that electric fields are more decisive in defining the minimum distances obtained.