Chapter 23, Problem 89A

To determine

To explain:The reason for not replacing the $15\text{ A}$ fuse with $30\text{ A}$ fuse, as it is dangerous to replace.

Explanation of Solution

Introduction:

Fuse and circuit breakers plays a vital role in any circuit. They prevent the damage of the electrical appliances connected in the circuit from the overloads. The fuse is generally connected in series in the appliances in the circuit. It melts and breaks the circuit when heavy current flows in the circuit.

The expression for the current through the fuse using the equivalent resistance is,

$I=\frac{V}{R}$

Here, $V$ is the voltage and $R$ is the resistance.

Consider the electric appliances are connected in series with the fuse in the circuit.The electric appliances work normally without any damage when the current flow in the circuit is $15\text{ A}$ .When a fuse rated $15\text{ A}$ is used in the circuit, the fuse will melt and break the circuit when the flow of the current in the circuit exceed $15\text{ A}$ . Hence, damage of the electric appliances due to excess current flow is prevented.When the fuse rated $\text{30 A}$ is replaced by the fuse of $15\text{ A}$ used in the circuit, the fuse will not melt when the flow of the current in the circuit exceed $15\text{ A}$ . Hence, the electric appliances get damaged due to the excess current flow in the circuit.

Hence, it is dangerous to replace the $15\text{ A}$ fuse with the fuse that is rated at $30\text{ A}$ .