Single Phase Electricity

Let me start answering your question from the generation of electricity.

Electricity is generated by Alternator/Generator through various ways like Hydroelectric, Thermal, Nuclear power etc. The Alternator produces ’Three-phase AC ’ electricity power and remember only in three wires, i.e. Delta connection.

To avoid transmission losses the voltage is stepped up (like 220KV, 110KV) through step-up transformers. (Note: Directly high voltage power can not be produced due to insulation and cooling limitations of Alternator).

After reaching near its load, the voltage of this 3-phase AC power is stepped down to 440 volts from 220 kilo-volts through various divisions and sub-divisions in your locality. In 440 volts the power supply is same 3-phase AC, however 4 electrical conductors/wires i.e. Star connection. Three phase conductors and one neutral conductor.

Now when you will look at the electric pole, from where your home electricity is coming, you will find 5 electrical conductors. Three phase/live conductors + one neutral conductor + one street light supply power conductor.

Your home connection is ‘Single phase AC’ connection that means, out of those 3 phase conductor any one conductor is connected with your live conductor and another one is connected with the one and only neutral conductor. (Note :out of those three phase/live conductors which one will be connected for your home depends on the load balance of all the three conductors i.e. yours and your neighbours wire may not be connected to same phase conductor that’s why sometimes when your power was cut your neighbour’s power is there.)

The two wires which come into your home, the one which is connected with the phase conductor called Live wire and the other one which is connected to the neutral wire is called Neutral. The current which you receive through the live wire is called Single-phase current, 230 volt (standard).

As the main supply into your home is single-phase the power which your wall socket gives is also single-phase. The additional middle and big socket is for Earthing system purpose only.

The bulbs glows dimmer and some appliances like the refrigerator do not work because the voltage required by them to run smoothly (normally 230 Volts) is not supplied to your home by the distribution company, this may be due to

• Less power generation and huge demand [Mostly this one] or
• Transmission losses or
• Electricity theft [More in India, especially villages*]

TVs and Radios work as they require less voltage to operate than refrigerator and bulb (tungsten).

Except Industries, corporate houses and large institutions all are supplied with single phase current supply ONLY. It does not has any relation with the single phase motor of farmers. In other way the motor manufacturer manufactured the single phase motors to farmers, so that they can use them directly as per the supply given by distributors.

I think this answers all your questions.

• In India to encourage people in villages to use electricity a fixed price has been charged to the villagers irrespective of their usage. Most of the times people take advantage of this scheme.

For enthusiastic nerds: Lalit Prakash’s answer to What is the difference between a star and a delta connection? What happens when it is star connected or delta connected? Are the circuits designed in our homes star or delta connected?