Abstract: The over heating process and arc beads characteristics of poor connection on aluminum conductor are studied by simulating different connection modes. The temperature of connection and the time of melting apart was measured, and the process of melting apart was observed by a high-speed camera. The appearance and metallographic structure of beads on the end of aluminum conductor arc were observed and compared. The results showed that for most hook connection, obvious parting arc appeared when melting apart, which need less time and lower temperature. The grain structure of beads presented fine cellular crystal and columnar crystal. When the conductors were connected by winding and hinging, obvious parting arc appeared rarely when melting apart. There were pointed weld marks, traces of winding, bonding and welding, and the grain structure of beads presented coarse equiaxed grain or columnar grain. This study provides the basis for the investigation of this kind of electrical fire and the identification of physical evidence.

Key words: fire investigation, electrical fire, poor connection, overheating fault, beads characteristics