Electrical Fire Patterns in Vegetation

The formation of branching patterns is commonly associated with electrical discharges. Lightning and electrostatic discharges from a Van DeGraff generator are transient luminous branching patterns, sometimes the passing of an electrical current leaves residual physical patterns. Such patterns can be captured in skin, sand, oil, and vegetation. Unfortunately for the fire investigator, patterns etched into wood-frame structures are often destroyed by subsequent combustion. Sometimes the patterns persist and can serve to indicate what actually happened. Char patterns were found etched into dry mustard plant, blackberry stalks, and Douglas fir. The first two were from current sourced by an electric fence charger (used for livestock management) and the third by contact between the tree and a power transmission line. Examples of how such patterns are formed are presented.