Which of the following should never be used to extinguish an electrical fire?

Using water to extinguish an electrical fire is highly dangerous and can result in severe consequences. Electrical fires involve live electrical equipment or wiring, and water is a conductor of electricity. If water is applied to an electrical fire, it can create a path for the electrical current to flow through the water, which may lead to electrocution for anyone attempting to extinguish the fire or cause the fire to spread further.

Foam and dry powder extinguishers have their own specific uses and are more suitable for different types of fires, but water should always be avoided in circumstances involving electricity. Carbon dioxide extinguishers are effective for electrical fires as they do not conduct electricity and remove oxygen from the area to suppress the fire without introducing any additional risks associated with water.