Fire Investigations EXPLAINED (with real examples)

The fire department's prevention division conducts fire investigations to determine where and why a fire started. This video showcases approximately a dozen training burns performed in a house on Second Street. These burns allow new employees from the DCI, State Fire Marshal's office, and Wausau Fire Department to gain real-world experience in identifying areas of origin and cause.

Investigators begin by checking if doors were forced open. Within the room, they look for areas of least to most damage. Signs like cracked paint, smoke staining, soot deposition, and charring indicate heat exposure. A 'V-shaped pattern' often points to the seat of the fire. A 'line of demarcation' shows where hot gases were present. This specific room shows significant heat damage at higher levels due to rising heat. The room did not flash over, and good ventilation led to air entrainment, feeding the fire. The fire in this section was intentionally set, as no competent ignition sources were found.

In a bathroom investigation, a v-shaped demarcation points to the fire's origin. Damage to the upper part of a hollow core door indicates extensive burning. Investigators check switch plates, outlets, and light fixtures for failures. A curling iron in the sink is examined, and its unplugged status suggests it might not be the cause. A significant burn pattern under the counter and a wastebasket indicates a potential starting point, with charring and calcination showing the fire's intensity and spread.

In a combined living and dining room area, burned carpeting under pallets indicates an irregular fire pattern. This suggests either the pallets were moved by suppression crews or an accelerant was used. An accelerant detection canine from the State Fire Marshal's Office would be called in to confirm the presence of accelerants, with samples then tested in a lab.

This kitchen presents two distinct areas of origin. One involves a small crock-pot, where investigators would check for arcing in its stranded copper cord. While the device may not have been energized, significant burning on the countertop suggests a fire there. The second area is inside a cabinet, where a v-shaped burn pattern indicates heavy charring and heat trapped underneath the countertop, suggesting two separate fire ignitions.

Fires can spread rapidly, emphasizing the critical role of working smoke alarms for early detection and safety. Fire alarms provide precious seconds to escape, as fires burn hot and fast. The speaker, a former paramedic firefighter, transitioned to fire prevention for its proactive nature. The role of a fire investigator is described as a 'crime fighter,' involving continuous learning and problem-solving, as no two fire scenes are ever the same.