Which class includes ordinary combustibles and is commonly fought with water-based extinguishers?

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

Answer: (C)

Fires involving ordinary combustibles are best tackled with water-based extinguishers because water cools the burning material, lowering its temperature below the point where it can keep oxidizing. This heat absorption interrupts the combustion process, helping the fire to go out and stay out as long as the fuel source isn’t reintroduced. Water-based extinguishers are specifically effective for solid fuels like wood, paper, and textiles.

They aren’t suitable for fires involving flammable liquids, where water would spread the liquid and fuel the flame; nor for energized electrical equipment, since water conducts electricity and can pose a shock hazard; nor for metal fires, which require special extinguishing agents.