Which extinguishing agent leaves no corrosive residue and does not conduct electricity?

• A. Carbon Dioxide
• B. Aqueous Film Forming Foam
• C. ABC Dry Chemical
• D. Water

Answer: (A)

Choosing an extinguishing method for electrical or equipment-heavy fires hinges on residues and electrical conductivity. Carbon dioxide extinguishes by displacing the air and smothering the fire, and because it is a gas, it leaves no chemical residue on surfaces or gear and it does not provide a path for electricity. That combination—no corrosive residue and no conductive medium—makes it the best fit for electrical fires or areas with sensitive equipment.

Other options don’t satisfy both requirements. Water can conduct electricity and can cause short circuits or corrosion; it also leaves mineral residues after drying. Aqueous film forming foam leaves a film that must be cleaned and can be corrosive or cause residue issues on equipment. ABC dry chemical powders leave dusty residues that can be corrosive and may contaminate or foul electrical components.