Fires due to Electric Arcing: Can ‘Cause’ Beads Be Distinguished from ‘Victim’ Beads by Physical or Chemical Testing?

A wide variety of physical or chemical testing methods have been proposed for differentiating between an electric arc bead that caused a fire, versus one that was caused by the fire itself. The methods all implicitly assume that there is some categorical difference between these two types of arc beads. A consideration of the room fire process leads to the conclusion that the thermal or chemical histories in these two cases cannot be claimed to be categorically different. Furthermore, most of the proposed methods only entail subjective, qualitative criteria for distinguishing between beads that did or did not start a fire. Finally, all of the methods have been based on studies where only a small number of specimens were tested; none of the methods have been successfully reproduced in laboratories other than the proponent’s, while several have been shown explicitly not to be reproducible. Thus, despite the help to fire investigations that would be possible if a reliable method could be produced, it must be concluded that none of the proposed methods are promising.