Science (086) — AI-generated practice question

Although both the neutral and earth wires are at 0 V (earth potential) under normal conditions, they serve different purposes. The neutral wire carries the return current during normal operation, while the earth wire is a dedicated safety conductor connected to a metal plate deep in the earth.

For appliances with metallic bodies (e.g., electric press, refrigerator), the body is connected to the earth wire. If a fault occurs and the live wire accidentally touches the metallic body, the earth wire provides a low-resistance conducting path for the leakage current directly to the earth. This keeps the potential of the metallic body at earth potential (0 V), preventing the user from receiving a severe electric shock.

Without the earth wire, the faulty metallic body would become live at 220 V, making contact with it dangerous.

Source: Chapter 12, Section 12.4 — Domestic Electric Circuits

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• Examiners expect you to distinguish between the function of the neutral wire (carries return current) and the earth wire (safety path for fault current).
• Key phrase to include: "low-resistance conducting path" — this exact language comes from the textbook and is likely expected.
• Mention at least one example appliance (refrigerator, electric press, etc.) to show context.
• The core logic: under a fault, the earth wire diverts leakage current safely away, keeping the appliance body at 0 V so the user is not shocked. This is different from the neutral wire, which is part of the active circuit and not dedicated to fault protection.