A blue circle with a letter designation on an extinguisher indicates suitability for which class of fires?

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

Answer: (C)

Recognizing extinguisher labeling helps you pick the right type for the fire. A blue circle with a letter indicates suitability for electrical fires, i.e., Class C. This matters because fires involving energized electrical equipment require an extinguishing agent that won’t conduct electricity and won’t worsen the electrical hazard, making it the safest and most effective choice for those situations. Other fire types—ordinary combustibles, flammable liquids, or metals—use different markings and extinguishing methods, so the blue circle is the cue that this extinguisher is for electrical fires.