Ensuring electrical safety in medical equipment is crucial for effective patient treatment and protects both the operator and the patient. This paper discusses the electrical safety of external cardiac defibrillators in the post-market context, focusing on the ABNT NBR IEC 62353:2019 standard. Through a systematic approach, the study addresses the technical criteria prescribed in the standard, highlighting key tests such as protective earth resistance, insulation resistance, and leakage current. The analysis underscores the importance of these tests in ensuring the safety of cardiac defibrillators within an university hospital. Furthermore, the study includes the execution of electrical safety tests on two defibrillators from different brands and models. This analysis explores the unique features and functionalities of each medical equipment. Initial measurements of electrical quantities associated with these tests provided insights into the integrity of the equipment’s electrical safety. Notably, one of the defibrillators failed to meet the normative limit for protective earth resistance, while the other exhibited insulation resistance values very close to the established limit.