Ohio Fire Extinguisher Practice Exam 2025 - Free Fire Extinguisher Practice Questions and Study Guide

Water can be harmful when used on Class C fires, which involve electrical equipment. The reason for this is that water is a conductive material. When water is applied to an electrical fire, it can conduct electricity, posing a serious risk of electric shock to anyone attempting to extinguish the fire. Furthermore, using water on a Class C fire can exacerbate the situation by allowing the fire to spread, especially if the water causes a short circuit or if it comes into contact with live wires.

For clarity, Class B fires, which involve flammable liquids, and Class K fires, associated with cooking oils and fats, should not be put out with water as well; however, the primary concern with water is its conductivity on Class C fires. Class A fires, which involve ordinary combustibles like wood and paper, can be effectively extinguished with water, as it helps to cool and suppress the fire without the risks seen with electrical fires.