Magnetic effects of Electric Current:- Part 4

 Domestic electric circuits 

-> Electricity generated by a power plant is usually AC. Its voltage is 11000 V to 22000 V. The power stations are located far away from the cities and industrial areas and hence transmission of electricity is done with the help of high tension cables by stepping up the voltage to 300000 V- 400000 V. 

   Before distribution of the voltage, the electric voltage is brought down to 11000 V, 440 V, or 220 V as per the requirement using a step-down transformer. 

 

-> At our home, we receive 220 V AC. In the household circuit, three cored cables are used. Each core cable is a copper wire capable of withstanding about 15 A of current.  

-> The old color convention is red as live wire or phase wire, black as neutral wire, and green as earth wire. 

-> The new color convention is brown as a live wire, light blue as neutral wire, and green or yellow as earth wire. 

Note:- Nowadays, the ring system of wiring is used in households. In the ring system, all appliances are connected in parallel. As a result, if the fuse of any appliance blows off, it does not affect the remaining appliances. 

Safety measures in using electricity

1. Use wires of high quality and of good insulating material.

2. Cover all naked wires and joints with insulating tape.

3. All connections at plugs, switches, sockets must be tight.

4. Replace any defective plugs, switches, and sockets.

5. Never touch any part of the circuit without putting on rubber shoes or rubber gloves.

6. Use the Fuse of proper rating and material.

7. All electrical appliances must be properly earthed.

8. Do not use water as a fire extinguisher in case of fire due to electricity.

Earthing or Grounding 

-> The process of sharing the charges with the earth by connecting a device to the earth is called grounding or earthing. To ensure good contact with the earth, a large metal plate is buried under the earth at a depth where the soil is moist. 

  This plate is surrounded by a mixture of charcoal and common salt to ensure good contact between the wet soil and flow the current easily. The earthing wire is usually bare and thick. If the metal casing of the appliance is connected to the earth with the help of a conductor then the metal casing will be at the same potential as the earth i.e. zero volts. 

  Earthing provides a low resistance path for the current thus allowing the excessive current to flow to the earth and not through the body of the person using the appliance.  

Note:- One gets an electric shock from an electrical appliance if its live wire comes in contact with its metal casing.

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