NFPA 921 PRACTICE EXAM 2025 QUESTIONS AND
ANSWERS RATED A+
✔✔Arc - ✔✔High temperature luminous electric discharge across a gap or through a
medium such as charred insulation.
✔✔Arc Mapping - ✔✔The systematic evaluation of the electrical circuit configuration,
spatial relationship of the circuit components and
Identification of electrical arc sites to assist in the identification of the area of origin and
analysis of the fire spread
✔✔Arc Site - ✔✔That location on the conductor with localized damage that resulted
from an electrical arc.
✔✔Fire and Energy - ✔✔Fire is a rapid oxidation process, which is an exothermic
chemical reaction, resulting in the release of heat and light energy in varying intensities.
✔✔Arcing through Char - ✔✔Arcing associated with a matrix of charred material (e.g.,
charred conductor insulation) that acts as a semiconductive medium.
✔✔Area of Origin - ✔✔A structure, part of a structure, or general geographic location
within a fire scene, in which the "point of origin" of a fire or explosion is reasonably
believed to be located. (See also 3.3.142, Point of Origin.)
✔✔Arrow Patterns - ✔✔A fire pattern displayed on the cross- section of a burned
wooden structural member.
✔✔Arson - ✔✔The crime of maliciously and intentionally, or recklessly, starting a fire or
causing an explosion.
✔✔Autoignition - ✔✔Initiation of combustion by heat but without a spark or flame.
✔✔Auto ignition Temperature - ✔✔The lowest temperature at which a combustible
material ignites in air without a spark or flame.
✔✔Backdraft - ✔✔A deflagration resulting from the sudden introduction of air into a
confined space containing oxygen- deficient products of incomplete combustion.
✔✔Bead - ✔✔A rounded globule of re-solidified metal at the end of the remains of an
electrical conductor that was caused by arcing and is characterized by a sharp line of
demarcation between the melted and unmelted conductor surfaces.
, ✔✔Blast Pressure Front - ✔✔The expanding leading edge of an explosion reaction that
separates a major difference in pres‐ sure between normal ambient pressure ahead of
the front and potentially damaging high pressure at and behind the front.
✔✔BLEVE - ✔✔Boiling liquid expanding vapor explosion.
✔✔Bonding - ✔✔The permanent joining of metallic parts to form an electrically
conductive path that ensures electrical continuity and the capacity to conduct safely any
current likely to be imposed
✔✔British Thermal Units - ✔✔The quantity of heat required to raise the temperature of
one pound of water 1°F at the pressure of 1 atmosphere and temperature of 60°F; a
Brit‐ ish thermal unit is equal to 1055 joules, 1.055 kilojoules, and 252.15 calories.
✔✔Burning rate - ✔✔AKA Heat release rate
✔✔Calcination of Gypsum - ✔✔A fire effect realized in gypsum products, including
wallboard, as a result of exposure to heat that drives off free and chemically bound
water.
✔✔Calorie - ✔✔The amount of heat necessary to raise 1 gram of water 1°C at the
pressure of 1 atmosphere and temperature of 15°C; a calorie is 4.184 joules, and there
are 252.15 calories in a British thermal unit (Btu).
✔✔CAUSE - ✔✔The circumstances, conditions, or agencies that brought about or
resulted in the fire or explosion incident, damage to property resulting from the fire or
explosion inci‐ dent, or bodily injury or loss of life resulting from the fire or explosion
incident.
✔✔CEILING JET - ✔✔A relatively thin layer of flowing hot gases that develops under a
horizontal surface (e.g ceiling) as a result of plume impingement and the flowing gas
being forced to move horizontally.
✔✔CEILING LAYER - ✔✔Buoyant layer of hot gases and smoke produced by a fire in a
compartment.
✔✔CHAR - ✔✔Carbonaceous material that has been burned or pyrolized and has a
blackened appearance.
✔✔CHAR BLISTERS - ✔✔Convex segments of carbonized material separated by
cracks or crevasses that form on the surface of char, forming on materials such as
wood as the result of pyroly‐ sis or burning.
ANSWERS RATED A+
✔✔Arc - ✔✔High temperature luminous electric discharge across a gap or through a
medium such as charred insulation.
✔✔Arc Mapping - ✔✔The systematic evaluation of the electrical circuit configuration,
spatial relationship of the circuit components and
Identification of electrical arc sites to assist in the identification of the area of origin and
analysis of the fire spread
✔✔Arc Site - ✔✔That location on the conductor with localized damage that resulted
from an electrical arc.
✔✔Fire and Energy - ✔✔Fire is a rapid oxidation process, which is an exothermic
chemical reaction, resulting in the release of heat and light energy in varying intensities.
✔✔Arcing through Char - ✔✔Arcing associated with a matrix of charred material (e.g.,
charred conductor insulation) that acts as a semiconductive medium.
✔✔Area of Origin - ✔✔A structure, part of a structure, or general geographic location
within a fire scene, in which the "point of origin" of a fire or explosion is reasonably
believed to be located. (See also 3.3.142, Point of Origin.)
✔✔Arrow Patterns - ✔✔A fire pattern displayed on the cross- section of a burned
wooden structural member.
✔✔Arson - ✔✔The crime of maliciously and intentionally, or recklessly, starting a fire or
causing an explosion.
✔✔Autoignition - ✔✔Initiation of combustion by heat but without a spark or flame.
✔✔Auto ignition Temperature - ✔✔The lowest temperature at which a combustible
material ignites in air without a spark or flame.
✔✔Backdraft - ✔✔A deflagration resulting from the sudden introduction of air into a
confined space containing oxygen- deficient products of incomplete combustion.
✔✔Bead - ✔✔A rounded globule of re-solidified metal at the end of the remains of an
electrical conductor that was caused by arcing and is characterized by a sharp line of
demarcation between the melted and unmelted conductor surfaces.
, ✔✔Blast Pressure Front - ✔✔The expanding leading edge of an explosion reaction that
separates a major difference in pres‐ sure between normal ambient pressure ahead of
the front and potentially damaging high pressure at and behind the front.
✔✔BLEVE - ✔✔Boiling liquid expanding vapor explosion.
✔✔Bonding - ✔✔The permanent joining of metallic parts to form an electrically
conductive path that ensures electrical continuity and the capacity to conduct safely any
current likely to be imposed
✔✔British Thermal Units - ✔✔The quantity of heat required to raise the temperature of
one pound of water 1°F at the pressure of 1 atmosphere and temperature of 60°F; a
Brit‐ ish thermal unit is equal to 1055 joules, 1.055 kilojoules, and 252.15 calories.
✔✔Burning rate - ✔✔AKA Heat release rate
✔✔Calcination of Gypsum - ✔✔A fire effect realized in gypsum products, including
wallboard, as a result of exposure to heat that drives off free and chemically bound
water.
✔✔Calorie - ✔✔The amount of heat necessary to raise 1 gram of water 1°C at the
pressure of 1 atmosphere and temperature of 15°C; a calorie is 4.184 joules, and there
are 252.15 calories in a British thermal unit (Btu).
✔✔CAUSE - ✔✔The circumstances, conditions, or agencies that brought about or
resulted in the fire or explosion incident, damage to property resulting from the fire or
explosion inci‐ dent, or bodily injury or loss of life resulting from the fire or explosion
incident.
✔✔CEILING JET - ✔✔A relatively thin layer of flowing hot gases that develops under a
horizontal surface (e.g ceiling) as a result of plume impingement and the flowing gas
being forced to move horizontally.
✔✔CEILING LAYER - ✔✔Buoyant layer of hot gases and smoke produced by a fire in a
compartment.
✔✔CHAR - ✔✔Carbonaceous material that has been burned or pyrolized and has a
blackened appearance.
✔✔CHAR BLISTERS - ✔✔Convex segments of carbonized material separated by
cracks or crevasses that form on the surface of char, forming on materials such as
wood as the result of pyroly‐ sis or burning.
