The construction of electric power substations poses a great number of risks due to its dangerous environment. The objective of this work was to evaluate the perception of construction workers on risks, methods they use for evaluation and managing risks to which they are exposed. This study carried out a qualitative and quantitative analysis during the expansion of one electric substation, adding an additional 100 MVA power transformer. The risks were identified and analysed by using the Preliminary Risk Analysis (PRA). Additionally, a questionnaire on construction safety was created and applied on all 27 workers which participated in the construction. The results showed which activities are present during the construction of a power substation, which risks are involved and how to manage them. It was found that among several, the PRA and Checklists were the most commonly used analysis tools. Further on, it was found a relation between training and risk perception. Among perceived risks were: noise, working at heights, electric shocks, traffic accidents, poisonous animals, dust, fire and explosions. The conclusion of this study was that the construction of electric power substations brings several safety risks and that the instruction of workers allows an effective risk management, and can reduce the number of accidents in this type of working activity.