Which media is suitable for Class B and C fires?

• A. Water
• B. Dry chemical
• C. CO2
• D. Foam

Answer: (C)

When choosing a fire extinguisher media for fires involving flammable liquids (Class B) and energized electrical equipment (Class C), you want something that can suppress the flame without conducting electricity and without leaving a damaging residue. Carbon dioxide does exactly that: it blankets the fire, displaces the surrounding oxygen to suffocate the flame, and it is non-conductive with no residue to clean up. This makes CO2 extinguishers safe to use on live electrical gear and effective for small, contained Class B fires.

Keep in mind the limitations: CO2 is less effective for large fuel spills or fires in open spaces where people are present due to the risk of asphyxiation. Other media have their uses—water is dangerous on electrical fires and can spread flammable liquids; foam works well on some liquids but isn’t ideal for energized equipment; dry chemical can handle both B and C but may leave a conductive or corrosive residue that isn’t desirable for electrical gear. Overall, CO2 best fits both Class B and C scenarios in typical practice.