What do the A B C ratings mean on Fire Extinguishers? FE Rating – A“A” TRASH–WOOD–PAPER Fire extinguishers with a Class A rating are effective against fires involving paper, wood, textiles, and plastics. FE rating – B“B” LIQUIDS Fire extinguishers with a Class B rating are effective against flammable liquid fires. These can be fires where cooking liquids, oil, gasoline, kerosene, or paint have become ignited. FE rating – C“C” ELECTRICAL EQUIPMENT Fire extinguishers with a Class C rating are suitable for fires in “live” electrical equipment. Fire Extinguisher Ratings Fire extinguishers are classified by fire type. The A, B, C rating system defines the kinds of burning materials each fire extinguisher is designed to fight. The number in front of the A, B, or C indicates the rating size of fire the unit can extinguish. To achieve a Class “A” rating, the extinguisher must be capable of putting out the wood crib, wood panel and excelsior (shredded paper) tests. Ratings are based on the size of the material that can be repeatedly extinguished.