A blue circle with a letter designation in the center indicates an extinguisher is rated for use on which class of fires?

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

Answer: (C)

In extinguisher labeling, a colored circle with a letter shows which fire class it can handle. A blue circle with the letter inside indicates suitability for electrical fires (Class C). This matters because electrical fires require non-conductive extinguishing media, like dry chemical or CO2, and you should avoid water. So this symbol tells you the extinguisher is intended for electrical equipment fires, not for ordinary combustibles, flammable liquids, or metal fires. If possible, cut power to the equipment before applying, and use the appropriate non-conductive agent.