What does an arc refer to in fire investigations?

In the context of fire investigations, an arc specifically refers to an electric discharge that occurs across a gap. This phenomenon typically happens when there is an electrical fault, such as a short circuit or a breakdown in insulation, leading to a sudden and intense flow of electric current. The energy released during this discharge can generate significant heat and may ignite surrounding materials, thereby playing a crucial role in understanding potential ignition sources in an investigation.

Understanding electric arcs is essential for fire investigators because they can indicate electrical malfunctions that contributed to a fire's origin. Analyzing the characteristics of an arc discharge can provide valuable evidence about how and why a fire started, which is critical for determining the cause of a fire.

In contrast, while fire patterns are important in assessing how a fire spread, they are not the same as an arc. Determining fire cause often involves examining various evidence and factors, rather than focusing solely on arcs. Additionally, chemical combustion refers to a different process altogether, mainly involving the rapid reaction of fuel and oxygen, which does not directly define an arc.