short circuit, overload and fuse

1. To understand the working principle behind an electrical fuse, two critical concepts should be kept in mind :

2. fuse

2.1. fuse is a safety device.

2.2. it is the weakest part of the circuit which melts and breaks the electric circuit.

2.2.1. Current flows in a loop

2.2.2. Heating effect of current

2.2.3. Electric current can flow through a conductor only when the circuit formed is complete. If there is a break in the loop, electric charges cannot flow through. This is also how switches operate. For example, when you put on the light switches at home, the lights come on because you have just completed the circuit allowing charges from the power source to flow through and power your lights.

3. Miniature Circuit Breakers (MCBs)

3.1. This ore increasingly being used these days in place of fuses. MCB does not work on the heating effect of current as it works on the magnetic effect of current.

3.2. These switches automatically turn OFF when the current in a circuit exceeds the safe limit. We turn them ON and the circuit ¡s once again completed.

4. circuit

4.1. 1) red wire is live wire

4.2. 2)black wire is neutral wire

4.3. 3) the green wire is earth wire

4.3.1. metallic body of an electric appliance is connected to the earth wire

4.3.2. earthing gives protection from shock when the appliance is touches.

5. overload

5.1. It is a situation when too many electrical appliances are connected to a single socket, they draw an extremely large amount of current from the household circuit. The flow of large current due to overloading may heat the copper wires of household wiring to a very high temperature and fire may be started.