CFI CFI Electrical & Mechanical Fire Causes

Question 1

What is the most common electrical cause of structure fires in residential buildings in the United States?

Accepted Answer

Arcing and sparking from electrical wiring faults

Answer

Lightning strikes

Answer

Overloaded extension cords

Answer

Faulty circuit breakers

Question 2

In electrical fire investigation, what does 'arc mapping' refer to?

Accepted Answer

Documenting the location of electrical arc beads throughout a fire scene to help determine fire origin and direction of travel

Answer

Drawing the electrical floor plan of a building

Answer

Testing the electrical system after the fire

Answer

Mapping the location of circuit breakers

Question 3

What distinguishes a 'primary arc bead' from a 'secondary arc bead' in fire investigation?

Accepted Answer

A primary arc bead occurred before or at the time of fire ignition, while a secondary arc bead resulted from fire damage to the wiring

Answer

Primary arc beads are larger than secondary arc beads

Answer

Primary arcs occur in 120V circuits and secondary arcs in 240V circuits

Answer

Primary arc beads are found on aluminum wiring only

Question 4

Which condition is most associated with 'series arc faults' in residential electrical systems?

Accepted Answer

Damaged or deteriorated wiring where conductors are incompletely separated

Answer

Overloaded extension cords

Answer

Moisture intrusion in electrical panels

Answer

Improperly grounded outlets

Question 5

What is 'thermal runaway' in the context of lithium-ion battery fires?

Accepted Answer

A self-sustaining exothermic reaction within a battery cell where heat generation exceeds heat dissipation, leading to fire or explosion

Answer

A battery overheating due to direct flame exposure only

Answer

Normal heat generation during charging

Answer

Overheating caused by short circuit only

Question 6

What type of electrical fault occurs when current flows along an unintended path between two conductors of different potential without forming a complete circuit arc?

Accepted Answer

Ground fault

Answer

Series arc fault

Answer

Parallel arc fault

Answer

Tracking fault