Earth Wire Ensures Electrical Safety

Steps:

• Identify the earth wire's role in a three-pin plug: it connects the appliance's metal casing to the ground.
• Recall that faults can cause live wire current to flow through the casing.
• Understand that the earth wire diverts this fault current safely to the ground.
• Confirm the primary purpose is human protection, not circuit completion or appliance function.

Why C is correct:

• The earth wire grounds the appliance's metal parts, allowing fault currents to flow to earth instead of through a person, per electrical safety standards like grounding principles in Ohm's law (current follows lowest resistance path).

Why the others are wrong:

• A: The live and neutral wires complete the circuit; earth is for safety only.
• B: Thermal management uses insulation or design, not the earth wire.
• D: Fuses or circuit breakers protect against overloads, not the earth wire.

Final answer: C