Analysis of Visual Characteristics of Short-circuited Arc Sites

Identifying the cause of fire at a fire site is an important fire prevention measure to prevent recurrence. In particular, information about molten marks of the copper wire is essential to check whether electric power is being supplied at the fire site. This study aims to analyse the visual characteristics of arc sites formed by a short circuit to identify the molten marks at the fire site. When a short circuit occurs, electromagnetic force is generated by the short circuit current, and the arc repulsion force is generated by the contact arc. In this study, the effects of the forces, which act on the short-circuited melted area, on the formation of copper molten marks were investigated. Copper molten marks formed by a short circuit were experimentally fabricated, and the visual characteristics based on the force that was applied to the melted area were identified and classified based on features. The results showed that the melted area was affected by both the arc repulsion and electromagnetic forces, resulting in the visual differences between the short-circuited arc sites and flame-melted ones, which are affected by gravity and molecular force. These results provide a theoretical basis for discriminating between arc sites formed by a short circuit and flame-melted marks at the fire site. The validity of this study was verified via a comparative analysis using shape and cross-sectional microstructure of molten marks collected at the fire site.