2017 NFPA 921 Guide - Current Edition

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Added information in the 2017 edition of NFPA 921 helps you work more accurately to investigate fire origin and cause.

If your job involves investigating fires and explosions, then you need the latest NFPA 921: Guide For Fire & Explosion Investigations. Revised and updated for the 2017 edition, this document is the premier source for rendering scientific based opinions on origin and cause investigations along with incident responsibility.

NFPA 921 describes in detail the scientific method to apply in fire and explosion investigations. Public and private professionals have long seen NFPA 921 as a valuable resource in the field and in training. It's also becoming increasingly relevant in U.S. federal and state courts, where the document is used to evaluate the reliability of fire investigations in both civil and criminal trials.

Recently NFPA 921 became a recommended guide for fire investigation by the Organization of Scientific Area Committees (OSAC) -- a collaborative body of more than 600 forensic science practitioners and experts who recommend forensic science consensus standards and guidelines. Complying with NFPA 921 can support a fire investigator's opinion; not complying can result in serious challenges to your testimony.

NFPA 921 also offers essential guidance on:

  • Using the scientific method in origin and cause investigations
  • Documenting an investigation so that all relevant facts are gathered for future use in court
  • Handling fire-related evidence so that it's admissible in court
  • Understanding many of the terms related to explosion and fire investigations

Changes in the 2017 edition reflect user needs in a challenging field.

  • Chapter 1 was revised to support Fire Marshal and Fire service organizations in the completion of reports from the National Fire Incident Report System (NFIRS). These reports were being misapplied and compared to Fire Investigation Reports during courtroom testimony. The committee added to scope of NFPA 921 to distinguish an NFIRS Report from a Fire Investigation Report and identified one should not be used in lieu of the other, especially when NFIRS are outside the scope of NFPA 921.
  • Chapter 8, Fire Protection Systems, was renamed Active Fire Protection Systems since passive systems are addressed in Chapter 7, Building Systems. New images and illustrations were added based on NFPA 72®: National Fire Alarm and Signaling Code® and the Fire Protection Handbook.
  • Updated Chapter 16, Documentation reflects technology breakthroughs in the areas of digital photography and 3D scanning.
  • Chapter 18, Origin includes the concept of origin matrix addressing the impact of ventilation on origin determination.

Featuring additional new full-color images, especially for Fire Protection Images.

Full-color images, first added to the previous edition and continued for the 2017 edition, communicate and demonstrate key concepts and examples more clearly, so you gain a better understanding of the principles of fire and explosion investigation. Make sure you have the most up-to-date information on investigating fires and explosions in the 2017 edition of NFPA 921. (Softbound, Approx. 394 pp., 2017)

NFPA® 921 Guide for Fire and Explosion Investigations, 2017 Edition

Chapter 1 Administration
1.1 Scope.
1.2 Purpose.
1.3 Application.
1.4 Units of Measure.
1.5 Measurement Uncertainty.
Chapter 2 Referenced Publications
2.1 General.
2.2 NFPA Publications.
2.3 Other Publications.
2.4 References for Extracts in Advisory Sections.
Chapter 3 Definitions
3.1 General.
3.2 NFPA Official Definitions.
3.3 General Definitions.
Chapter 4 Basic Methodology
4.1 Nature of Fire Investigations.
4.2 Systematic Approach.
4.3 Relating Fire Investigation to the Scientific Method.
4.4 Basic Method of a Fire Investigation.
4.5 Level of Certainty.
4.6 Review Procedure.
4.7 Reporting Procedure.
Chapter 5 Basic Fire Science
5.1 Introduction.
5.2 Fire Chemistry.
5.3 Products of Combustion.
5.4 Fluid Flows.
5.5 Heat Transfer.
5.6 Fuel Load, Fuel Packages, and Properties of Flames.
5.7 Ignition.
5.8 Flame Spread.
5.9 Fire Spread in a Compartment.
5.10 Compartment Fire Development.
5.11 Fire Spread Between Compartments.
5.12 Paths of Smoke Spread in Buildings.
Chapter 6 Fire Patterns
6.1 Introduction.
6.2 Fire Effects.
6.3 Fire Patterns.
6.4 Fire Pattern Analysis.
Chapter 7 Building Systems
7.1 Introduction.
7.2 Features of Design, Construction, and Structural Elements in Evaluating Fire Development.
7.3 Types of Construction.
7.4 Construction Assemblies.
7.5 Construction Materials.
7.6 Impact of Passive Fire Protection Systems on Investigation.
7.7 Design and Installation Parameters of the System.
7.8 Documentation and Data Collection.
7.9 Analysis.
Chapter 8 Active Fire Protection Systems
8.1 Introduction.
8.2 Documentation of Fire Protection Systems.
8.3 Fire Alarm Systems.
8.4 Water-Based Fire Suppression Systems.
8.5 Non-Water-Based Fire Suppression Systems.
8.6 Spoliation Issues.
Chapter 9 Electricity and Fire
9.1 Introduction.
9.2 Basic Electricity.
9.3 Building Electrical Systems.
9.4 Service Equipment.
9.5 Grounding.
9.6 Overcurrent Protection.
9.7 Branch Circuits.
9.8 Outlets and Devices.
9.9 Ignition by Electrical Energy.
9.10 Interpreting Damage to Electrical Systems.
9.11 Identification of Arc Melting of Electrical Conductors.
9.12 Static Electricity.
Chapter 10 Building Fuel Gas Systems
10.1 Introduction.
10.2 Fuel Gases.
10.3 Natural Gas Systems.
10.4 LP-Gas Systems.
10.5 Common Fuel Gas System Components.
10.6 Common Piping in Buildings.
10.7 Common Appliance and Equipment Requirements.
10.8 Common Fuel Gas Utilization Equipment.
10.9 Investigating Fuel Gas Systems Incidents.
Chapter 11 Fire-Related Human Behavior
11.1 Introduction.
11.2 History of Research.
11.3 General Considerations of Human Responses to Fires.
11.4 Factors Related to Fire Initiation.
11.5 Children and Fire.
11.6 Incendiary Fires.
11.7 Human Factors Related to Fire Spread.
11.8 Recognition and Response to Fires.
Chapter 12 Legal Considerations
12.1 Introduction.
12.2 Constitutional Considerations.
12.3 Legal Considerations During the Investigation.
12.4 Pretrial Legal Considerations.
12.5 Trials.
Chapter 13 Safety
13.1 General.
13.2 General Fire Scene Safety.
13.3 Fire Scene Hazards.
13.4 Safety Plans.
13.5 Chemical and Contaminant Exposure
13.6 Personal Protective Equipment (PPE).
13.7 Emergency Action Plans.
13.8 Post-Scene Safety Activities.
13.9 Safety in Off-Scene Investigation Activities.
13.10 Special Hazards.
Chapter 14 Sources of Information
14.1 General.
14.2 Legal Considerations.
14.3 Forms of Information.
14.4 Interviews.
14.5 Governmental Sources of Information.
14.6 Private Sources of Information.
14.7 Conclusion.
Chapter 15 Planning the Investigation
15.1 Introduction.
15.2 Basic Incident Information.
15.3 Organizing the Investigation Functions.
15.4 Pre-Investigation Team Meeting.
15.5 Specialized Personnel and Technical Consultants.
15.6 Case Management.
Chapter 16 Documentation of the Investigation
16.1 Introduction.
16.2 Photography.
16.3 Note Taking.
16.4 Diagrams and Drawings.
16.5 Reports.
Chapter 17 Physical Evidence
17.1 General.
17.2 Physical Evidence.
17.3 Preservation of the Fire Scene and Physical Evidence.
17.4 Contamination of Physical Evidence.
17.5 Methods of Collection.
17.6 Evidence Containers.
17.7 Identification of Physical Evidence.
17.8 Transportation and Storage of Physical Evidence.
17.9 Chain of Custody of Physical Evidence.
17.10 Examination and Testing of Physical Evidence.
17.11 Evidence Disposition.
Chapter 18 Origin Determination
18.1 Introduction.
18.2 Overall Methodology.
18.3 Data Collection for Origin Determination.
18.4 Analyze the Data.
18.5 Developing an Origin Hypothesis.
18.6 Testing of Origin Hypotheses.
18.7 Selecting the Final Hypothesis.
18.8 Origin Insufficiently Defined.
Chapter 19 Fire Cause Determination
19.1 Introduction.
19.2 Overall Methodology.
19.3 Data Collection for Fire Cause Determination.
19.4 Analyze the Data.
19.5 Developing a Cause Hypothesis.
19.6 Testing the Cause Hypothesis.
19.7 Selecting the Final Hypothesis.
Chapter 20 Classification of Fire Cause
20.1 Classification of the Cause.
Chapter 21 Analyzing the Incident for Cause and Responsibility
21.1 General.
21.2 The Cause of the Fire or Explosion.
21.3 The Cause of Damage to Property Resulting from the Incident.
21.4 The Cause of Bodily Injury or Loss of Life.
21.5 Determining Responsibility.
Chapter 22 Failure Analysis and Analytical Tools
22.1 Introduction.
22.2 Time Lines.
22.3 Systems Analysis.
22.4 Mathematical Modeling.
22.5 Fire Testing.
22.6 Data Required for Modeling and Testing.
Chapter 23 Explosions
23.1 General.
23.2 Types of Explosions.
23.3 Characterization of Explosion Damage.
23.4 Effects of Explosions.
23.5 Factors Controlling Explosion Effects.
23.6 Seated Explosions.
23.7 Nonseated Explosions.
23.8 Gas/Vapor Combustion Explosions.
23.9 Dust Explosions.
23.10 Backdraft (Smoke Explosions).
23.11 Outdoor Vapor Cloud Explosions.
23.12 Explosives.
23.13 Investigation of Explosive Incidents.
23.14 Investigating the Explosion Scene.
23.15 Analyze Origin (Epicenter).
23.16 Analyze Fuel Source.
23.17 Analyze Ignition Source.
23.18 Analyze to Establish Cause.
Chapter 24 Incendiary Fires
24.1 Introduction.
24.2 Incendiary Fire Indicators.
24.3 Potential Indicators Not Directly Related to Combustion.
24.4 Other Evidentiary Factors.
Chapter 25 Fire and Explosion Deaths and Injuries
25.1 General.
25.2 Mechanisms of Death and Injury.
25.3 Consumption of the Body by Fire.
25.4 Postmortem Changes.
25.5 Investigating Fire Scenes with Fatalities.
25.6 Investigating Fire Scenes with Injuries.
25.7 Explosion Deaths and Injuries.
25.8 Post Scene Investigation of Injuries.
25.9 Fire Death Pathological and Toxicological Examination.
25.10 Analysis of Data.
Chapter 26 Appliances
26.1 Scope.
26.2 Appliance Scene Recording.
26.3 Origin Analysis Involving Appliances.
26.4 Cause Analysis Involving Appliances.
26.5 Appliance Components.
26.6 Common Residential Appliances.
Chapter 27 Motor Vehicle Fires
27.1 Introduction.
27.2 Vehicle Investigation Safety.
27.3 Fuels in Vehicle Fires.
27.4 Ignition Sources.
27.5 System Identification and Function.
27.6 Body Systems.
27.7 Motor Vehicle Fire Scenes.
27.8 Motor Vehicle Examinations.
27.9 Total Burns.
27.10 Special Considerations for Incendiary Vehicle Fires.
27.11 Vehicle Ignition Components.
27.12 Vehicles in Structures.
27.13 Recreational Vehicles.
27.14 Heavy Equipment.
27.15 Agricultural Equipment and Implements Introduction.
27.16 Hybrid Vehicles.
27.17 Towing Considerations.
27.18 Hydrogen-Fueled Vehicles.
Chapter 28 Wildfire Investigations
28.1 Introduction.
28.2 Wildfire Fuels.
28.3 Weather.
28.4 Topography.
28.5 Fire Shape.
28.6 Indicators.
28.7 Origin Investigation.
28.8 Fire Cause Determination.
28.9 Evidence.
28.10 Special Safety Considerations.
28.11 Sources of Information.
Chapter 29 Management of Complex Investigations
29.1 Scope.
29.2 Basic Information and Documents.
29.3 Communications Among Interested Parties.
29.4 Understandings and Agreements.
29.5 Management of the Investigation.
29.6 Evidence.
29.7 Logistics.
29.8 Site and Scene Safety.
Chapter 30 Marine Fire Investigations
30.1 Introduction.
30.2 Powerboat and Sailboat Terminology.
30.3 Boat Investigation Safety.
30.4 System Identification and Function.
30.5 Exterior.
30.6 Interior.
30.7 Propulsion Systems.
30.8 Ignition Sources.
30.9 Documenting Boat Fire Scenes.
30.10 Boat Examination.
30.11 Boats in Structures.
30.12 Legal Considerations.
Annex A Explanatory Material
Annex B Bibliography
Annex C Informational References
Annex D Photograph Credits

NFPA 921 is the field's leading reference for safe and systematic fire and explosion investigations.

Whether you're investigating a residential fire or a complex industrial disaster, the most important resource for fire investigators, litigators, and insurance professionals is NFPA 921: Guide for Fire and Explosion Investigations. This trusted Guide addresses every stage of a very complex process -- from basic fire investigation methodology to collecting evidence to failure analysis. Each edition is updated based on the most recent court cases, scientific data, and trends, to help you offer expert testimony and render opinions that stand up to scrutiny.

  • The 2014 edition of NFPA 921: Guide for Fire and Explosion Investigations marks the first time the Guide includes color images. This enhancement allows us to communicate and demonstrate key concepts and examples more clearly. As a result, readers will gain a better understanding of the principles of fire and explosion investigation.
  • The 2011 edition of NFPA 921: Guide for Fire and Explosion Investigations has a rewritten Chapter 18 on cause that helps ensure fire investigators use scientific methodology when developing hypotheses, avoiding errors and Daubert challenges. An all-new section outlines the report review process in fire investigation and discusses peer vs. technical review. A critical update concerning explosion investigations features new illustrations and photos. Numerous other changes help users respond to growing and emerging fire problems, such as vehicle fires involving electric/hybrids and their potential for high voltage hazards impacting investigators.
  • The 2008 edition of NFPA 921: Guide for Fire and Explosion Investigations clarifies the process investigators should use to identify and recognize fire effects and fire patterns. Other changes present a more comprehensive, systems approach for dealing with complex incidents -- such as those involving fatalities or injuries, fires in high-rises or building complexes, and fires or explosions in industrial plants or commercial properties. A new chapter on marine fire investigations provides first-time coverage of fire and explosion investigations involving recreational boats, including safety issues due to environmental contaminants. 

Interested in other editions of NFPA 921? Use the drop down menu above to select the edition year you need.

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Sample (NEC® 2014)

411.2411.3 Definition. Low-Voltage Lighting Systems.


(A) General. Lighting Ssystems Ooperating at 30 Volts- volts or  Less. A lighting system consisting less shall consist of an isolating power supply, the low-voltage luminaires, and associated equipment that are all identified for the use. The output circuits of the power supply are shall be rated for not more than 25 amperes and  operate at 30 volts (42.4 volts peak) or lessmaximum under all load conditions.


(B) Class 2. Listed Class 2 lighting equipment shall be rated in conformance with Chapter 9, Table 11(A) or Table 11(B).


411.3411.4 Listing Required. Lighting systems operating at 30 volts or less shall comply with 411.3(A)411.4(A) or 

411.3(B).411.4(B). Class 2 power sources and lighting equipment connected to Class 2 power sources shall be llisted.