Environmental impacts of electrical transformer manufacturing vary according to transformer power distribution capacity and metal type used in coil manufacture. 75 Kilovolt-ampere (kVA) transformers are widely used in light poles, residential buildings, and other locations, and copper and aluminum are the main metals used for coil manufacturing. Life cycle assessment (LCA) methodology was used to evaluate the environmental impact of copper and aluminum use in the 75 kVA transformer manufacturing process. Cradle-to-gate LCA was considered, and a distribution capacity of 75 kVA was adopted as functional unit. Results were obtained through SimaPro ^® software and three environmental impact methods: Eco-indicator 99, CML 2, and ReCiPe. Coil type showed significant influence on environmental impacts due to the metal used in its production. Results of the comparison between coil types showed that the copper coil has more adverse effects on the environment. The main environmental impact attributed to aluminum coil is associated with its global warming potential due to a high energy requirement in aluminum production (75.7 MJ/kg) in comparison with copper (22.8 MJ/kg). Greenhouse gas emissions (in terms of carbon dioxide emissions, CO ₂ ) from 75 kVA manufacturing with copper coil were, in average, 888.71 kg carbon dioxide equivalent (CO ₂ eq) and 1,226.27 kg CO ₂ eq with aluminum coil. Copper coils have a major contamination potential on terrestrial and marine environments. Some harmful effects on human health associated with copper mining and production are caused by the toxicity of heavy metals such as antimony, arsenic, cadmium, chromium, zinc, nickel, and mercury. Final results showed that copper has higher environmental impacts due to the production and emissions of heavy metals in its manufacturing process that cause more adverse effects on the environment in comparison with greenhouse gas emissions.