What should fire investigators examine in smoke detectors and alarms?

Fire investigators focus on soot accumulation, soot patterns, and thermal impact in smoke detectors and alarms because these elements can provide crucial insights into the conditions present during a fire event. Soot accumulation can indicate the intensity and duration of the fire. Patterns of soot can reveal airflow or ventilation factors that influenced how smoke traveled and how the detector responded to the fire. Additionally, examining thermal impact can help assess whether the detector or alarm functioned correctly under fire conditions and whether it was compromised by excessive heat. This information is vital for determining the fire's behavior and can assist in understanding the origin and cause of the fire, which are core elements of fire investigation.

The other considerations, such as procedure manuals or installation cost reports, while potentially useful in a broader context, do not provide immediate physical evidence or direct indications of fire behavior that would assist in an investigation's specifics. User complaints may yield anecdotal information but lack the tangible evidence required to analyze the performance and effectiveness of the smoke detectors and alarms during the fire incident.