Question 1: Define the function of the Live wire in a mains electricity supply.

Answer: The Live wire carries the alternating voltage from the power supply to the appliance.

Question 2: Explain why the Neutral wire is connected to Earth at the main fuse box.

Answer: To ensure the Neutral wire is at Earth potential, reducing the risk of electric shock and providing a safe return path.

Question 3: What safety measure is provided by the Earth wire in household appliances?

Answer: It provides a low-resistance path for current to flow to Earth in case of a fault, preventing electric shocks.

Question 1: Calculate the current flowing through a 2400 W electric oven connected to a 230 V mains supply. Use the formula: Power (W) = Voltage (V) × Current (A).

Answer: 10 A

Question 2: A household circuit has a fuse rated at 13 A. If the supply voltage is 230 V, what is the maximum power that can be safely used without blowing the fuse?

Answer: 2990 W

Question 1: List three safety precautions to observe when working with live wires in household installations.

Answer: Turn off the mains supply, wear insulated gloves, and use insulated tools.

Question 2: Describe the steps you would take to safely test whether a wire is live using a voltage tester.

Answer: Ensure the mains is turned on, set the voltage tester to the correct voltage range, carefully touch the probe to the wire, and observe the tester's indication. Always wear protective equipment and keep hands away from the wire.

Question 1: A household appliance has a fault where the casing is live. Explain the role of the Earth wire in preventing electric shock in this scenario.

Answer: The Earth wire provides a low-resistance path for current to flow directly to Earth, causing the fuse to blow and disconnecting the appliance, thus preventing electric shock.

Question 1: Explain the importance of earthing appliances in mains electricity systems and the potential hazards if earthing is not properly implemented.

Answer: Earthing provides a safe pathway for fault current to flow to the ground, reducing the risk of electric shock and fire. Without proper earthing, a fault could cause the appliance casing to become live, posing serious electric shock hazards to users.

Question 1: Describe how the principles of mains wiring are applied in the design of consumer safety devices such as circuit breakers and residual current devices (RCDs).

Answer: Circuit breakers disconnect the supply when current exceeds safe levels, and RCDs detect imbalances between Live and Neutral currents, disconnecting the supply to prevent electric shocks. Both rely on understanding the roles of Live, Neutral, and Earth wires for safety.