Question

Distinguish between overloading and short-circuiting as used in domestic circuits.

Answer 1

Hint: Overloading as the name signifies, refers to an overflow of current through an electrical circuit. A short circuit happens when the ends of a circuit are connected by a lower resistance path as compared to that of the circuit. Both these cases will result in damage to electrical appliances.

Complete step by step answer:

Overloading usually occurs when a large number of electrical appliances which have a high power-rating are switched on simultaneously and as a result, these appliances draw a huge amount of current from the main supply which will be greater than the maximum current a mainline can hold. This will lead to the damage of electrical appliances due to overheating of the wires.

The short circuit usually happens when the ends of a circuit are connected by a conductor of lower resistance path as compared to that of the circuit. In this situation, the neutral and live wires of an electric circuit come in direct contact which provides a path whose resistance is very close to zero.

\[I=\dfrac{V}{R}=\dfrac{V}{0}=\infty \text{ }\left( \because R\approx 0 \right)\]

As a result, the current through the circuit increases abruptly which will lead to the damage of electric appliances and can produce sparks at the point of contact, which could lead to a fire breaking out.

In both cases, there is a huge increase in current which causes damage to the circuit. But the cause of these effects is different as you can see from the explanations above.

Note: An electrical fuse which consists of a fuse wire made of nichrome (an alloy of nickel and chromium) which has a very low melting point are installed in a circuit so that when there is a huge increase in the current, the fuse wire melts due to the heating effect produced by the current as a result the circuit is saved from the huge current produced.
The material used for a fuse wire should have a very low melting point, high conductivity, high specific heat, low ohmic loss and low oxidation power.