In our homes, we receive the supply of electric power through a main supply also called mains, either supported through overhead electric poles or by underground cables. In our country the potential difference between the two wires (live wire and neutral wire) of this supply is 220 V.
(a) Write the colours of the insulation covers of the line wires through which supply comes to our homes.
(b) What should be the current rating of the electric circuit (220 V) so that an electric iron of 1 kW power rating can be operated ?
(c) What is the function of the earth wire? State the advantage of the earth wire in domestic electric appliances such as electric iron.
OR
(c) List two precautions to be taken to avoid electrical accidents. State how these precautions prevent possible damage to the circuit/appliance.

Question

KnowledgeBoat · Accepted Answer

(a) The insulation colours of the wires in domestic circuits are:

(b) Given,

Current rating of the iron is given by,

$\text I = \dfrac{\text P}{\text V} \\[1em] = \dfrac {1000}{220} \\[1em] \Rightarrow \text I \approx 4.5\ \text A$

Hence, the current rating of the circuit should be about 4.5 A.

(c) The earth wire provides a path for the leakage current to flow safely into the ground in case of insulation failure.

Advantage : It prevents the metal body of appliances like an electric iron from becoming live, thereby protecting users from electric shocks.

OR

(c) Two precautions to avoid electrical accidents:

Use of proper fuse: Prevents excessive current from flowing through the circuit by melting and breaking the circuit, protecting appliances from damage.
Never touch electrical appliances with wet hands: Water conducts electricity and can cause electric shocks; keeping hands dry ensures safety.

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