Fuses are designed to protect electrical circuits from damage due to excess current. When a circuit is overloaded and the current flowing through it exceeds the fuse's rated capacity, the fuse will "blow," or interrupt the flow of electricity to prevent damage to the circuit.
In most electrical systems, the neutral wire carries a current back to the source of electricity, completing the circuit. This current is typically much smaller than the current flowing through the live (also called "hot") wire.
Because the neutral wire carries a much smaller current, it is not necessary to protect it with a fuse. If a fuse were placed in the neutral wire, it would not blow until the current flowing through it exceeded the fuse's rated capacity, which is unlikely to occur under normal circumstances.
It is important to note that the fuse should always be placed in the live wire, as this is the wire that carries the full load current and is most likely to experience an overload. Placing the fuse in the neutral wire would not provide sufficient protection for the circuit.