Certified Fire Investigator Practice Exam

What is meant by spontaneous ignition?

1. Ignition caused by an external spark

2. Combustion initiated by an internal reaction

3. The use of accelerants for ignition

4. Ignition caused by extreme heat exposure

The correct answer is: Combustion initiated by an internal reaction

Spontaneous ignition refers to a process where combustion occurs without the need for an external ignition source, such as a spark or flame. This phenomenon typically happens when materials undergo an internal reaction, which can generate enough heat to reach their ignition temperature. For example, organic materials, like oily rags or compost piles, can undergo oxidation that increases their temperature over time. If the heat generated exceeds the material's capacity to dissipate it, spontaneous ignition can occur, resulting in combustion without any external ignition source being present. Understanding this concept is crucial for fire investigators, as it helps in identifying the causes of fires, particularly in cases where no clear ignition source is evident at the scene.