Question 1: Define the primary function of the Live wire in a mains electrical system.

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 distribution board.

Answer: To maintain a constant potential close to Earth potential and to complete the circuit safely.

Question 3: What is the typical voltage of the Live wire in the UK mains supply?

Answer: 230 volts

Question 1: An appliance connected to the mains has a resistance of 50 Ω and is supplied with a voltage of 230 V. Calculate the current flowing through the appliance using Ohm's law.

Answer: I = V / R = 230 V / 50 Ω = 4.6 A

Question 2: A safety earth wire is connected to an appliance with a resistance of 0.5 Ω. If the earth wire carries a fault current of 30 A, calculate the voltage drop across the earth wire.

Answer: V = I × R = 30 A × 0.5 Ω = 15 V

Question 1: List three safety precautions that should be taken when handling live wires in a domestic setting.

Answer: Ensure the power is switched off before working, use insulated tools, and avoid contact with live parts.

Question 1: A household circuit supplies a total power of 2 kW at 230 V. Calculate the total current drawn by the household circuit.

Answer: I = P / V = 2000 W / 230 V ≈ 8.7 A

Question 2: If a fault causes the live wire to become live with 230 V relative to Earth, explain the role of the Earth wire in preventing electric shock.

Answer: The Earth wire provides a low-resistance path to Earth, allowing fault currents to safely bypass users and trip the circuit breaker, preventing electric shocks.

Question 1: Explain the importance of earthing appliances and how it enhances safety in domestic electrical systems. Include relevant safety standards and practical considerations.

Answer: Earthing provides a safe path for fault currents to flow directly to Earth, reducing the risk of electric shock and fire. It ensures that metal parts of appliances do not become live. Safety standards require proper earthing connections and regular inspections. Practically, earthing systems must be correctly installed, protected by earth-fault circuit breakers, and maintained to prevent corrosion or disconnection, thus safeguarding users against electric shocks and electrical fires.

Question 1: Describe how the principles of earthing are applied in the design of electrical appliances and safety systems in modern homes.

Answer: Earthing in appliances ensures that any fault current is safely directed to ground, activating circuit breakers or fuses to disconnect power, thereby protecting users from electric shocks. Modern safety standards require appliances to be properly earthed, with robust wiring and protective devices to prevent electric hazards.