Use a ____ fire extinguisher on a fire involving energized electrical equipment.

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

Answer: (C)

When a fire involves energized electrical equipment, you need an extinguisher rated for electrical fires. Water should never be used on electricity-fueled fires because it conducts electricity and can shock you or energize the equipment further. A Class C extinguisher is designed for fires in energized electrical equipment; its agents are non-conductive and safe to use on live circuits.

The other classes address different fuel sources: ordinary combustibles, flammable liquids, and combustible metals, which aren’t appropriate for electrical fires. So the best choice is the Class C extinguisher.