what are the characteristics of electricity supplied for domestic use?describe with the diagram.

Asked by nishac | 28th Dec, 2009, 11:29: AM

Expert Answer:

The electric power line enters our house through three wires- namely the live wire, the neutral wire and the earth wire. To avoid confusion we follow a colour code for insulating these wires. The red wire is the live wire, and the black wire is neutral. The earth wire is given green plastic insulation.

The live wire has a high potential of 220 volts whereas the neutral wire has zero potential. Thus the potential difference between the live wire and the neutral wire is 220-0 = 220 volts.

The earth wire is much thicker in size and is made of copper. One end of it is connected to a copper plate buried deep under the earth. The earth connection is made to the electric meter and then to the main switch.

The live wire and neutral wire, coming from the electric pole, enter a box fitted just outside our house which has a main fuse F1. The fuse is connected in series with the live wire. This is done so because it is only the live wire which has a high potential of 220 volts unlike the neutral wire which carries zero potential. The fuse F1 has a high rating of about 50 amperes. Thus it prevents any damage such as fire to the entire electrical  wiring entering the house due to short-circuit or overloading.

  • There are two separate circuits in a house namely lighting circuit and powercircuit. The lighting circuitwith a 5 A fuse is used for running electric bulbs, fan, radio, TV, tube lights etc. and the powercircuitwith a 15 A fuse is used for running electric heater, electric iron, geyser, refrigerator etc as it draws more current.
  • The ditribution circuits are always connected in parallel combination. In a parallelcircuit even if there is a fault or short-circuiting in any one line, the corresponding fuse blows off leaving the other circuits and appliances intact and prevents damage to the entire house.
  • In case short-circuitoccurs in the power circuit, then the power-fuse will blow off but our lights will continue to burn as the lightingcircuit remains unaffected.
  • A constant voltage of the main line is available for all other electrical appliances.
  • Along with the two wires, a third wire called the earth wire also enters our house as shown in the fig. The earth connection is first made to the electric meter and then to the main switch. This wire then goes into the rooms along with the live and neutral wires.

Answered by  | 28th Dec, 2009, 12:37: PM

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