There is always a potential for danger when dealing with electricity. We call a sudden increase in current a surge. This can be caused by a range of factors, such as a faulty appliance, bad wiring, lightning strikes and many more factors. Surges can lead to fires or electric shocks.
There are built-in safety measures that include fuses and earth wires, which reduce the risk of such damage. Both fuses and earth wires act in a similar way, breaking the circuit when the current gets too high.
A fuse contains a thin piece of wire which is connected to the live wire. When there is a surge, the high current will flow through the fuse. As the wire is very thin, it heats up quickly, which causes the wire to melt. Once the wire melts, the circuit breaks, which means that no more current can flow.
Fuses come in little cases with thin wire inside the casing.
There are different ratings for fuses, which depend on how much current you want to break the circuit.
This means if you have a 5 amp appliance, you should use a fuse that breaks the circuit at a current a couple amps above 5 A.
There can be an electrical fault in the circuit, for example, if the live wire loosens and touches the casing. If a person touches the casing, they would receive a huge electric shock. To prevent this, the earth wire gives the current an alternative path to flow. However, this also prevents the appliance from operating.
The earth wire is made of copper, which means that it provides a low-resistance pathway for the electric current to flow. This current is directed into the ground. So, instead of passing through the human, it follows a different pathway into the ground.
Circuit breakers act in a similar way to fuses, as they break the circuit whenever the current gets too high. However, circuit breakers are electrical switches that do not get permanently damaged when they break the circuit. Instead, they turn off once they get tripped. So, the circuit breaker can easily be reset instead of needing to be replaced.