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

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

Answer: (C)

That blue circle with a letter in the center marks an extinguisher rated for Class C fires. Class C fires involve energized electrical equipment, so the extinguishing agent must be non-conductive and safe to use on live electricity. Water or other conductive liquids can cause shock or spread the fire, so extinguishers with non-conductive agents like dry chemical powder, CO2, or clean agents are used. The symbol therefore identifies suitability specifically for electrical fires, where de-energizing the equipment when possible and selecting the appropriate non-conductive agent are key.