Final answer:
A Class C fire extinguisher is designed to work on electrical fires. Class C extinguishers contain non-conductive substances, making them safe to use on fires involving energized electrical equipment.
Step-by-step explanation:
The class of fire extinguisher designed to work on electrical fires is Class C. Fire extinguishers are categorized by the types of fires they are designed to extinguish. Class A extinguishers are for ordinary combustible materials like wood and paper, Class B are for flammable liquids such as grease or gasoline, Class C are for electrical equipment, and Class D are for flammable metals.
For an electrical fire, which typically involves energized electrical equipment, a Class C fire extinguisher is necessary because it contains non-conductive substances. This ensures that the person using the extinguisher is not at risk of electrical shock. Once the electrical equipment is de-energized, in many cases a Class A extinguisher would suffice, since most electrical fires involve plastic and rubber components once the electrical current is removed.