Abstract: Residual magnetism method often encounters legal disputes in the practice of investigating the causes of vehicle fire. In order to explore whether the residual magnetism method is applicable to vehicle fire, four simulation experiments were designed and conducted based on the characteristics of vehicle electrical fire. The results indicate that the electrical short-circuit energy inside the engine compartment is insufficient to cause changes in the residual magnetic field of the vehicle body. Certain locations in the engine compartment and vehicle body exhibit inherently higher residual magnetic values, causing interference in the residual magnetism method. Additionally, the effect of high temperatures during a fire and post-fire towing and maintenance operations can cause the magnetic properties to fade, affecting the measurement of the vehicle's remanent magnetization value. Ultimately, it is confirmed that the residual magnetism method is not suitable for the investigation and determination of the causes of vehicle fire.

Key words: residual magnetism method, vehicle fire, fire investigation, electrical fault