Class A fires involve which materials?

Class A fires involve which materials?

• A. Ordinary combustibles
• B. Flammable liquids
• C. Electrical equipment
• D. Metals

Answer: (A)

Fires are grouped by the type of fuel and how they behave, which determines the best extinguishing approach. Class A is defined by ordinary combustibles—materials that commonly burn in everyday environments and leave ash after burning. This includes wood, paper, textiles, rubber, and many everyday plastics. These fuels respond well to cooling with water, which lowers the material’s temperature below its ignition point and prevents reignition, making water-based extinguishers commonly effective for these fires. The other materials listed belong to different fire classes: flammable liquids (Class B) burn as liquids and vapors; electrical equipment (Class C) fires involve energized circuits and require nonconductive agents and power shutdown; and metals (Class D) require specialized powders for metal fires. Therefore, ordinary combustibles best define this class.

Fires are grouped by the type of fuel and how they behave, which determines the best extinguishing approach. Class A is defined by ordinary combustibles—materials that commonly burn in everyday environments and leave ash after burning. This includes wood, paper, textiles, rubber, and many everyday plastics. These fuels respond well to cooling with water, which lowers the material’s temperature below its ignition point and prevents reignition, making water-based extinguishers commonly effective for these fires. The other materials listed belong to different fire classes: flammable liquids (Class B) burn as liquids and vapors; electrical equipment (Class C) fires involve energized circuits and require nonconductive agents and power shutdown; and metals (Class D) require specialized powders for metal fires. Therefore, ordinary combustibles best define this class.