Which type of extinguisher is ineffective on electrical fires?

A Class A extinguisher is designed for fires involving ordinary combustible materials such as wood, paper, and textiles. It works by cooling the burning materials and removing the heat element necessary for combustion. However, when it comes to electrical fires, using water-based extinguishing agents commonly found in Class A extinguishers can pose a significant risk. This is due to the fact that water is a conductor of electricity, which may lead to electrical shock hazards and worsen the fire by adding an additional risk factor.

In contrast, Class C extinguishers are specifically formulated for use on electrical fires, making them safe and effective in those situations. Class B extinguishers address flammable liquids, while Class D extinguishers are tailored for combustible metals. Therefore, while other types of extinguishers have specific applications, the Class A extinguisher is not suitable for electrical fires due to the inherent risks involved in using water around electrical components.