<p>This study aims to identify the ignition occurrence mechanism and assess the risks based on a peculiar electrical accident case caused by tin (Sn) whisker growth on bare busbars. Whiskers, high-purity single crystal filaments that grow on the surface of Sn-coated materials, can lead to electrical shorts and fire hazards. Unlike previous whisker research, forensic analysis and experiments, both small-scale and full-scale, confirmed that whiskers were the primary cause of the accident. The physical and electrical characteristics of the whiskers were analyzed. Notably, it was newly identified that while whiskers alone do not cause short circuits, they can cause short circuits between busbars when moving ionized whiskers encounter obstacles such as circuit breakers or barriers. The experiments demonstrated that whiskers could generate significant arc energy, leading to severe carbonization patterns in the panel. Based on these findings, preventive measures such as adjusting relay settings and using insulation tubes and barriers were proposed, along with a revision of the Korea Electro-Technical Code (KEC) to mitigate the risks posed by whiskers. This research contributes to a deeper understanding of the ignition mechanism of electrical fires caused by whiskers and offers practical solutions to enhance electrical safety.</p>