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

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

Answer: (C)

Interpreting extinguisher labeling, a blue circle with a letter in the center shows the fire class the extinguisher is rated for. The letter C identifies Class C, which covers fires involving energized electrical equipment. This matters because the extinguishing agent for Class C fires must be nonconductive, so it won’t energize the equipment or pose a shock risk; common choices include dry chemical powders and carbon dioxide rather than water. If the fire were a different class, the label would show a different symbol or letter corresponding to that class, not this blue circle with C.