SAFE USE OF ELECTRICITY IN HOMES | FUSE | CIRCUIT BREAKER | EARTH WIRE

Safe Use Of Electricity In Homes

SAFE USE OF ELECTRICITY IN HOMES: In order to protect persons, devises and property from the hazards of electricity there is need of extensive in safety measure in house hold electricity. Take much care to use fuse and circuit breaker in an electric circuit as safety devices. They prevent circuit overloads that can occur when too many appliances are turned ON at the same time or when short circuit is occur in one appliances.

Fuse

Fuse is safety device that is connected in series with the live-wire  in the circuit to protect the equipment when excess current flows. It is short and thin piece of metal wire that melts when large amount of current flow through it. If a large, unsafe current passes through the circuit, the fuse melts and breaks the circuit before the wires becomes very hot and cause fire.

Fuses are normally rates as 5A, 10A, 13A, 30A, etc. Different types of fuses are shown below.

Following safety measure should be taken while using fuses in household electric circuits:

(i) Fuses to be used should have slightly more rating than the current which the electric appliances will draw under normal conditions. For examples, for light circuit choose 5A fuse as the current drawn by each lamps very small (about 0.4 A for a 100 W lamp). In such circuit, 10 lamps of 100 W can be calculated by using the formula P = VI

(ii) Fuses should be connected in the live-Wire so that the appliances will not be operate after the fuse has blown.

(iii) Switch OFF the main before changing any fuse.

Circuit Breaker

 The circuit breaker act as a safety device in the same way as a fuse. It disconnected the supply automatically if current exceed the normal value. It disconnected the supply automatically if current exceed the normal value. When the normal values current passes through the live-wire the electromagnet is not strong enough to separates the contact. If something goes wrong with the appliances and large current flow through the live-wire, the electromagnet will attract the iron strip to separate the contacts and break the circuit.The spring then keeps the contacts apart. After the fault is  repaired, the contacts can then pushed back through by pressing a button on the outside of circuit breaker box.

 Earth Wire 

 Sometimes, even the fuse cannot captured the high currents coming from the live wire into the house hold appliances.  Earthing further protects the user from electric shock by connecting the metal casing of the appliances to Earth (a wired connection through the bare ground). Many electrical appliances have metal cases, including cookers, washing machine and refrigerators. The earth wire provides the safe route for the current to flow through, if the live wire touches the casing. We will get an electric shook if the live wire inside an appliances comes loose and touch the metal casing.

however, earth circuit is connected to the metal casing, so the current goes through the earth wire instead of passing through our body and causing an electric shock. A strong current passes through earth wire because it has very low resistance. This break the fuse and disconnects the appliances.