Typically, fire extinguishers for the home are Class ABC extinguishers, which fight most kinds of household fires, says Carmody. The letters A, B, and C refer to the classes of fire. Class A includes ordinary combustibles, such as paper or wood. Class B fires involve liquids or gases and are generally kitchen fires. However, these may not work on serious oil fires that start in a deep fryer. For these fires, use a Class K fire extinguisher. These are usually found in commercial kitchens and restaurants but are beginning to find their way into homes, too. Because the chemicals in a Class K fire extinguisher conduct electricity, you must make sure all electrical appliances are off before using it. Class C fires involve a television or appliance plugged into an electrical socket. An ABC extinguisher covers all of these. One important thing to remember: Never use a water fire extinguisher on anything other than Class A fires.