Dry powder fire extinguishers are excellent all-round fire extinguishers, often recommended for use on vehicles and in homes. All powder fire extinguishers are red with a blue panel, are either ABC or BC rated and are safe to be used on fires involving electrical equipment. Dry powder extinguishers are not suitable for use in enclosed spaces such as offices, hotels, schools, etc, as the fire-fighting agent creates a cloud that can obscure vision. The contents may also create breathing problems.
Unfortunately, the additional benefit of ABC rated dry powder fire extinguishers being able to tackle flammable gas fires also has a major drawback. Ammonium phosphate can react with any water present to form phosphoric acid, which is corrosive and can seep into even the slightest cracks in equipment. For this reason, dry chemical ABC rated fire extinguishers should not be used on sensitive electrical equipment such as computers, switch installations, scientific instruments or aircraft, if other fire extinguishing options are available. In the event of an emergency when only a dry powder fire extinguisher is available, however, always remember that electrical equipment can be replaced, a human life cannot.