Physics

# Safe Use of Electricity

In the previous section you were informed about the dangers of electricity. In the present section, we will learn about the safe uses of electricity.

When using electricity at home, the safety measures that are needed:

1. Circuit breaker
2. Fuses
3. Correct connection of switch
4. Earth wire

Circuit breaker: Circuit breakers are used as safety devices. Generally this is placed near the front door of a house. Circuit breaker switches off the electrical supply in a circuit when there is an overflow of current. Circuit breaker disconnects the electrical supply in a definite part of the house. Without circuit breaker in a circuit, this excessive current can cause damage of home appliances or even start a fire.

Fuses: A fuse is a safety device. A fuse is included in an electrical circuit to prevent excessive current flow. The fuse is always connected to the live wire of electrical cables. A short thin piece of wire is used as a fuse. The fuse becomes hot and melts when the electric current flowing through it is greater than a definite value. As a result, the circuit is disconnected and the electrical appliances will be safe. If the fuse bums. the appliance will not be electrified any more. Before changing a fuse, you have to switch off the mains of electricity supply.

Correct connection of switch: A switch breaks or completes an electrical circuit. During switch connection in a circuit, an important precaution is that the switch must be fitted onto the live wire. For this, switching off will disconnect the high voltage source from the appliance instantly [Figure: a]. If the switch is fitted onto the neutral wire wrongly, the electric appliance will be ‘live’ even if the switch is ‘off [Figure: b] and increase the risk of electric shock.

Fig (1)                                                                Fig (2)

Earth wire: All electrical appliances or devices need at least two wires to form a complete circuit. These are the live (L) and neutral (N) wire. The live wire delivers the electrical energy to the appliance. On the contrary, the current returns back to the supply through the neutral wire and complete the circuit. The potential of neutral wire is zero. The earth wire is a low-resistance wire. It is usually connected to the metallic casing of the appliance. The circuit may be faulty from different reasons. Earthing of the casing prevents this from happening. In this case, the large current will flow from the live wire to the earth through the metal casing. As a result, the fuse will blow out and cut off the electric supply to the appliance. It is strongly recommended to provide an earthing to the refrigerator in houses for safe use of it.