A blue circle with a letter designation in the center indicates an extinguisher rated for use on

• A. Electrical / Class C
• B. Paper and Wood
• C. Grease Fires
• D. Flammable liquids

Answer: (A)

This question tests how extinguisher labels tell you what kinds of fires the agent can handle. A blue circle with a letter in the center identifies Class C, which is for electrical fires involving energized electrical equipment. That’s why this extinguisher is rated for electrical fires—it’s designed to be safe and effective on energized circuits. It wouldn’t be the right choice for ordinary combustibles like paper or wood, cooking oils, or flammable liquids, which are indicated by different symbols (for example, ordinary combustibles, greases, and liquids each have their own fire-class markings). So the blue circle with its letter specifically points to use on electrical fires.