The electrical system is subject to rules to guarantee a standard, where several factors can reduce its quality. This can lead to undesirable consequences, such as increased electrical losses in the distribution. As the technology advances and the constant presence of non-linear loads, the electrical network is subject to harmonic distortions that increase the effective value of the current, resulting in inconvenient effects, such as increased losses. In another words, a bigger fraction of the energy is lost by Joule effect and a smaller fraction came to the final consumers. In Brazil, the regulatory agency, in its recommendations, does not consider the effect of harmonic components, obtaining lower results for losses. So, to analyze the influence of these distortions on the operation of a distribution network, simulations were done with the test system LVTestCaseNorthAmerican, with 390 buses. Three distinct climatic cases were analysed, each with a load shape generated from fuzzy logic, all considering the presence of non-linear loads. The simulations were made in OpenDSS, and the losses demonstrated for the three situations. Finally, the importance of considering these distortions in the calculation of losses is discussed.