Investigate fire origin and cause with increased confidence and accuracy with the latest criteria provided by NFPA 921.

NFPA 921 sets the bar for scientific-based investigation and analysis of fire and explosion incidents. Referenced in the field, in training, and in court, it is the foremost guide for rendering accurate opinions as to incident origin, cause, responsibility, and prevention. It is intended for use by both public sector employees who are responsible for fire investigation and private sector professionals who conduct investigations for insurance companies or litigation purposes.

Some changes in the 2024 edition include:

- Additional guidance on an investigator's potential bias, opinions and expressions of certainty in the conclusions reached during an investigation.
- Changes to the impact that ventilation and the flow path a fire may follow removed from the area of origin as a result of firefighting activities as established in NFPA 1700 "Guide to Structural Firefighting"
- Relocation of fire effects on electrical systems and components to Chapter 6 while keeping interpretation of damage to electrical systems and arc surveying to Chapter 9.
- Expanded text regarding hybrid electric vehicles (HEV) and electric vehicles (EVs)
- Updated guidance and classifications to the Safety Chapter
- Revisions to chapter and terminology related to wildfire investigations