Question

In our houses we receive A.C. electric power of 220 V. In electric iron or electric heater cables having three wires with insulation of three different colours – red, black and green are used to draw current from the mains. What are these three different wires called? Name them colourwise. What is the potential difference between the red wire and the black wire? What is the role of the wire with green insulation in case of accidental leakage of electric current to the metallic body of an electrical appliance?

Hint:

The earth wire (green) is essential for safety in electrical circuits to prevent electric shocks by directing leakage currents to the ground.

Answer 1

(i) The three wires in an electric circuit with different colour insulation are: 
Red wire: Live wire (or Phase wire) – carries current from the power source. 
Black wire: Neutral wire – completes the circuit by providing a return path for the current. 
Green wire: Earth wire – provides a safety path for current to flow to the ground in case of a fault or leakage. 
(ii) The potential difference between the red (live) wire and the black (neutral) wire is typically \( 220V \) in standard domestic power systems. 
(iii) The green wire (earth wire) provides a path for the electric current to safely flow into the ground if there is a leakage of current to the metallic body of an electrical appliance. 
This prevents electric shock by diverting the current away from the user.