CFI CFI Electrical & Mechanical Fire Causes 2

Question 1

In investigating a mechanical fire cause, which component failure in internal combustion engines is most commonly associated with vehicle fires?

Accepted Answer

Fuel system leaks ignited by hot engine components or electrical sparks

Answer

Fuel system leaks that allow flammable fuel to contact hot engine surfaces or electrical ignition sources are the most common mechanical cause of vehicle fires.

Question 2

What mechanical condition can cause a dryer to start a fire even without electrical faults?

Accepted Answer

Lint accumulation in the exhaust duct restricting airflow and causing overheating

Answer

Lint accumulation in dryer exhaust ducts restricts airflow, causing the dryer to overheat, and the highly flammable lint itself can ignite from the heat.

Question 3

What is 'friction heating' as a fire cause in mechanical equipment?

Accepted Answer

Heat generated when two dry surfaces rub together during normal operation, causing ignition of nearby combustibles

Answer

Friction heating occurs when mechanical parts rub against each other due to lubrication failure or mechanical misalignment, generating enough heat to ignite nearby combustibles or the material itself.

Question 4

When investigating a fire of suspected mechanical origin involving rotating equipment, what physical evidence should an investigator look for at the origin?

Accepted Answer

Seized bearings, worn or scored shafts, displaced belts, and evidence of lubricant failure

Answer

Physical evidence of mechanical failure including seized bearings, scoring, belt displacement, and lubricant breakdown indicates friction or overheating as the ignition source.

Question 5

Which NFPA standard provides the most comprehensive guidance on vehicle fire investigation?

Accepted Answer

NFPA 921

Answer

NFPA 921, 'Guide for Fire and Explosion Investigations,' includes dedicated chapters on vehicle fire investigation methodology and physical evidence analysis.

(CFI) Certified Fire Investigator Practice Test

(CFI) Certified Fire Investigator Practice Test

CFI CFI Electrical & Mechanical Fire Causes 2