10 free, exam-style Certified Fire and Explosion Investigator (NAFI CFEI) practice questions with answers and explanations. No signup required. Work through them below, then take the full free NAFI CFEI practice test to study every exam domain.
These 10 free NAFI CFEI questions are organized by exam domain, so you can see how each part of the Certified Fire and Explosion Investigator blueprint is tested. Reveal the answer and explanation under each question.
An investigator completes a scene examination and, after testing, finds that two separate hypotheses for the fire's cause both remain fully consistent with all the available data. Under the scientific method required by NFPA 921, how should the cause be reported?
Correct answer: D - Classify the cause as undetermined
At a residential fire, the investigator eliminates every accidental ignition source they can identify but recovers no physical evidence affirmatively pointing to any specific cause. The investigator wants to classify the fire as incendiary. According to NFPA 921, this reasoning is:
Correct answer: C - Improper, because a cause cannot rest solely on eliminating other causes
Firefighters arrive at a closed, heavily smoke-charged room showing pulsing smoke at the door seams and no visible flame. Moments after the door is opened, a deflagration erupts outward. This event is BEST described as:
Correct answer: B - A backdraft caused by the sudden introduction of air
A post-flashover compartment fire contains a large quantity of unburned fuel, but its heat release rate is limited by the amount of air reaching the compartment. Opening an exterior door causes a sudden, dramatic increase in burning. This fire is:
Correct answer: B - Ventilation-controlled
An investigator observes large, shiny, blistered 'alligator' char on burned wood and is asked whether this proves an ignitable liquid accelerant was used. The correct position under NFPA 921 is that alligator char:
Correct answer: D - Is not a valid indicator of an accelerant or of fire intensity
During overhaul, an investigator notes window glass exhibiting 'crazing' - a dense network of short cracks. What does this fire effect actually indicate?
Correct answer: A - Rapid cooling of hot glass, such as from hose-stream water
While evaluating a possible ignition scenario, an investigator must decide whether a brief mechanical spark could have started a fire in ordinary wood framing. For the spark to qualify as a 'competent ignition source' under NFPA 921, it must have sufficient energy AND:
Correct answer: C - Transfer that energy to the fuel long enough to reach its ignition temperature
Tracing a branch circuit, an investigator finds a copper conductor with a small, rounded, resolidified globule and a sharp line of demarcation separating it from the undamaged wire. Compared with damage from external fire heat alone, this feature is most consistent with:
Correct answer: A - Electrical arcing (an arc bead)
An investigator conducts destructive testing on a suspect appliance and discards components before notifying the other known interested parties to the litigation. This conduct is most likely to be challenged in court as:
Correct answer: B - Spoliation of evidence
In analyzing an explosion, the investigator determines that the combustion reaction propagated through the unreacted fuel-air mixture at a speed greater than the speed of sound, producing a shock wave. This is properly classified as a:
Correct answer: C - Detonation
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