Question

A toaster-oven is rated at $1.2-1.4\text{kW}$ at $220\text{V}$. What should be the rating of the safety fuse in the oven?

• A. $2.85\text{A}$
• B. $5.45\text{A}$
• C. $3.20\text{A}$
• D. $6.50\text{A}$

Answer 1

The correct option is D $6.50\text{A}$

Given:
The voltage, $\text{V}=220\text{V}$
The power rating of the oven, $\text{P}=1.2-1.4\text{kW}$
i.e. the oven consumes a minimum power of $1.2\text{kW}$, and a maximum of $1.4\text{kW}$.
So, the minimum electric current needed for the oven is $\frac{\text{P}}{\text{V}}=\frac{1.2\times {10}^3}{220}=5.45\text{A}$
The maximum electric current needed is $\frac{\text{P}}{\text{V}}=\frac{1.4\times {10}^3}{220}=6.36\text{A}$
For the oven to operate safely, its fuse must not allow electric current greater than $6.36\text{A}$, i.e. the correct rating is $6.5\text{A}$.