Single-phase and three-phase electricity: differences in use

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Power: 1 phase versus 3 phase: differences in use

We use electricity every day to power equipment such as   Motor   fan   lights and other appliances. Let us look at the types of electrical systems we use.

This article discusses 1 phase electricity and 3 phase electricity. A 1 phase supply is the household electricity we normally use, suitable for modest demand. A 3 phase supply is used in industry or buildings with greater power demand. The details of each are as follows.

1.  An electrical system with 1 phase has a voltage of 220 – 230 volts ( Volt) and a frequency of 50 hertz ( Hz) There are 2 wires in the system:  
          - A line, phase or live wire, represented by the letter L (Line) 1 wire. The source describes checking it with a test screwdriver, whose internal indicator lights when it touches a live wire.
          - A neutral or zero wire, represented by the letter N (Neutral) The source describes its indicator as remaining off when checked with a test screwdriver.

For example, household sockets have 2 openings. The source describes a red indicator appearing at one opening during testing, then states that current does not flow there. To operate a lamp or appliance, both 2 wires are required to complete the circuit. Some sockets have 3 openings but are still a 1 phase system. The additional opening connects to protective earth ( ground ) to conduct leakage current to earth and improve safety. Appliances using this system have a 3 pin plug, commonly treated as a standard system overseas.

2. An electrical system with 3 phase electricity has a line-to-line voltage of 380 – 400 volts and a line-to-neutral voltage of 220 – 230 volts, with a frequency of 50 hertz ( Hz) The system contains 4 wires, comprising:  
          - live line wires 3 wire(s)  
          - a neutral wire 1 wire(s)

This system cannot be connected directly in its entirety to normal household lighting or appliances. You may wonder why 3 phase electricity is being introduced if ordinary household appliances cannot use it directly. The explanation is that introducing a 3 phase supply to a house does not mean using all 3 phases directly for each appliance. Instead, the 3 phase supply is divided into 1 phase 3 sets and distributed to different points of use. This distributes demand among the phases. The source claims this saves electricity charges under progressive kilowatt-hour tariffs, where higher consumption attracts higher rates. Accordingly, dividing consumption into 3 parts from the incoming 3 phase supply is described by the source as reducing consumption on each phase and avoiding higher tariff rates.

Installing a 3 phase supply involves higher initial costs, such as installation and deposits. The source describes possible long-term savings, recommending it mainly for large homes or buildings with many high-consumption points. Small homes or buildings with low consumption generally need only a single-phase supply.

General lighting normally uses 1 phase electricity. However, if a factory receives a 3 phase supply, the lights do not use all 3 phases directly; the incoming 3 phase supply is divided into 1 phase 3 sets distributed among the lighting points. The source describes this as balancing electricity use and saving charges. These 1 phase 3 sets should contain similar types, quantities and sizes of lamps to keep the electrical system balanced.

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