Final answer:
For electrical fires in computers, a Class C fire extinguisher is necessary because it contains non-conductive substances safe for such fires. Water should not be used as it conducts electricity and can cause hazards. Electrical safety systems help prevent these hazards.
Step-by-step explanation:
For an electrical fire in a computer, one should have a Class C fire extinguisher. The reason one should not use water to extinguish electrical fires is that water is a good conductor of electricity. Throwing water on electrical fires can lead to electric shock and may even exacerbate the fire. Instead, Class C fire extinguishers are recommended as they contain non-conductive substances that can safely put out the fire caused by energized electrical equipment. It's also important to remember to turn off the power source, if possible, to reduce the risk of thermal and shock hazards present in electrical fires.
Electrical safety systems, such as circuit breakers and fuses, are designed to interrupt excessive currents and prevent thermal hazards, while a three-wire system that includes live/hot, neutral, and earth/ground wires helps guard against both thermal and shock hazards by grounding the neutral wire and the case of the appliance.