For ordinary combustibles such as wood and paper, which extinguisher class is appropriate?

• A. Class C
• B. Class B
• C. Class A
• D. Class D

Answer: (C)

Fires involving ordinary combustibles like wood and paper are best handled with extinguishers labeled for Class A. These extinguishers work by removing heat from the fuel, cooling the material below its ignition temperature so the fire can’t continue. The typical agents used for Class A fires (water-based, foam, or dry chemical) are all about cooling and preventing reignition of solid fuels.

Other extinguisher types target different hazards. For flammable liquids, the goal is to suppress or smother the fuel vapors; for energized electrical equipment, you need a non-conductive agent; for combustible metals, you use a specialized powder. None of those match wood or paper, so Class A is the appropriate choice.