Electric fuse protect the electrical alliance
Fuse wire is used to protect a circuit.in our home wiring, we have used a fuse. all electrical materials we have used in our home wiring such as switch boards, switches, cables etc. have current carrying capacity (6a, 16a or more). if the current flowing through these materials exceeds their current carrying capacity, excess heat is generated. This heat may be great enough to burn wires and other materials and light a fire. Short circuit is the main reason for excessive current flow in a circuit.
Short circuit occurs when phases and neutral lines are connected together without resisitance. if we connect broken electrical appliances (phase and short neutral) to the plug point, there is no resistance between phase and neutral. there for large currents (theoretically unlimited) will flow through wires, switch boards and other materials. as I mentioned before all materials have current carrying capacity. when a short circuit occurs, the materials we have used in the cable can not handle this much current and that lead to heating and burning cables and other materials.
If we have used a fuse in our circuit, the current carrying capacity of the fuse wire is very low compared to other materials. there for every time a short circuit occurs, this fuse current fuses first wire blow rating and breaks the current flow before damage occurs.
We connect all loads (electrical equipment) between phase and neutral. the current flowing through the load is from phase to neutral. if the load is in good condition, must have some resistance, this resistance limits the flow of current from phase to neutral.
If there is an error (short circuit etc), a high current will be generated. this can cause the equipment to become hot and even burn. A fuse is a device designed to cut a circuit when a current passes through a certain level. this could be by a simple piece of fusible wire fuse or mechanical device can do a trip switch.
You also get rcds. it measures the incoming current to the circuit and the return current. if less return it, he will travel. Imbalance may be a simple mistake (leakage of the earth because of water etc) or it could be because of the current flowing through a person to the earth (electricity). rcds usually trip with 30 ma difference (0.03a). traveling mechanical fuses (over current) at 6 a, 10a, 16a, 32a etc. (for mains electric home voltage).
The fuse rating is selected so that the fuse breaks before the cable etc. in equipment, or buildings etc.