Which type of fire extinguisher should NOT be used on electrical fires?

Using a water fire extinguisher on electrical fires is inappropriate because water is a conductor of electricity. When water comes into contact with live electrical equipment or wiring, it can create a serious risk of electrocution for the person using the extinguisher and further propagate the fire. The primary function of a water fire extinguisher is to cool the burning material, which is effective for common combustibles, but it poses a significant hazard when applied to electrical sources.

In contrast, foam, dry powder, and CO2 fire extinguishers are specifically designed to handle electrical fires safely. Foam extinguishers can smother flames and provide a cooling effect without conductive risk, while dry powder extinguishers work effectively by interrupting the chemical reaction of the fire. CO2 extinguishers displace oxygen around the fire, effectively suffocating it without the risk of conducting electricity.