Difference Between Three-Phase and Single-Phase Power

In today’s advanced and technological upbringings, the power of electricity has become more than a human necessity. People use electricity for heating, cooling, refrigerating, using a computer, and many more.

Similar to your mobile and home appliances, you cannot function and be productive without plugging in your devices or charging your mobile phones in a day. Hence, electricity has recalibrated our lives since the day of its discovery.

Today, the United States accounts for one of the economic leaders in the $6 trillion global energy market.

In 2018, the electric use by fans and air-conditioning equipment for cooling the interior spaces of homes was the single largest use of electricity by the US residential sector, according to the US Energy Information Administration.

In the same year, EIA estimated that refrigeration was the largest single use of electricity in the commercial sector.

While these impactful facts increased your curiosity on electricity, have you ever wondered about the science behind the electronic load distribution and how electrical power works into your device?

Do you know that a single-phase power brings electricity to your residential home? Why do you think most people prefer three-phase power than a single-phase power?

In this article, you’ll discover the science and the difference between three-phase power and single-phase power.

But first, what is the phase in electricity?

Phase in Electricity

A phase is the current, or the voltage among an existing wire as well as a neutral cable. Its waveform of electronic signals will be analyzed by an oscilloscope, a digital device that draws a graph showing the instantaneous signal voltage as a function of time.

Further, a phase depends on its electric load distribution corresponding to a type of unit, whether a single-phase or a three-phase power.

A single-phase (1-phase) has less power, requiring two wires; while, three-phase (3-phase) requires more, including three or four wires.

What is a Single-Phase Power?

Single-phase power simultaneously changes the supply voltage of an AC power by a system. More often, single-phase power is known as “residential voltage,” since it is that most homes use.

In the distribution of power, a single-phase uses the phase and neutral wires. Phase wire carries the current load, while the neutral wire provides a path where the current returns.

It creates a single sine wave (low voltage). The common voltage for a single-phase power starts at 230V. Also, its frequency approximates to 50Hz.

Single-phase motors require extra circuits to work since a single-phase supply connecting to an AC motor doesn’t generate a rotating magnetic field. The power output of a single-phase supply is not constant, meaning its voltage supply rises and falls.

What are the advantages of using Single-Phase Power?

  1. Single-Phase Power generates electricity to residential homes and domestic supplies, since most appliances require only a small amount of power to function, including fans, heaters, television, refrigerator, and lights.

  2. The design and operation are plain and ordinary. It has a lightweight and compact unit, which the current through the line will be less when the transmission of voltage is high.

  3. Due to the reduction of I2R, the current is low. Meaning, single-phase power ensures the unit to operate at optimum with an increased efficiency of its transmission.

  4. Single-phase power is best to use with fractional, or lower horsepower units up to 5 HP.

What are the disadvantages of using Single-Phase Power?

  1. Small single-phase motors need an additional circuitry such as Motor Starters (similar to starter capacitors in fans and pumps), since its single-phase supply is insufficient for an initial start-up.

  2. Industrial motors require heavy electronic loads. Ergo, it cannot run on a single-phase supply.

What is a Three-Phase Power?

Three-phase power provides three alternating currents, with three separate electric services. Each leg of alternating current reaches a maximum voltage, only separated by 1/3 of the time in a full cycle.

In other words, the power output of a three-phase power remains to be constant, and it never drops into zero.

In a three-phase power supply, it requires four wires, namely one neutral wire and three-conductor wires. These three conductor wires are 120-degree distant from each other. Also, each AC Power Signal is 1200 out of phase with each other.

Moreover, there are two types of circuit configurations in a three-phase power supply, such as the Delta and the Star. The Delta Configuration requires no neutral wire and only all high voltage systems use it; while, Star Configuration requires a neutral wire and a ground wire.

What are the advantages of a Three-Phase Power?

  1. Run larger loads easily. Commercial and Industrial loads prefer a three-phase power supply since it requires more heavy electronic loads.

  2. Do not require any starters to three-phase motors used in big industries, since it has sufficient phase difference to supply initial torque for the motor to start.

  3. Three-phase power supply requires less conducting materials to transmit and distribute electrical power. Hence, it becomes more economical when it speaks about costs.

  4. As the number of phases increases in the system, the DC voltage of a three-phased power becomes smoother and more advantageous.

What are the disadvantages of a Three-Phase Power?

  1. Since the system voltage is quite high, the three-phase power supplies and motors maintain a high cost of insulation. Insulation depends on the voltage of the unit, while its size of the wire depends on the current.

  2. Three-phase power units cannot handle overload. Meaning, when it results in damage, the cost of repair is higher since changing individual components is expensive.

What are the differences between Single-Phase Power and Three-Phase Power?

Required Wirings on Power Supply

In a single-phase power supply, it only requires two wires, namely Phase and Neutral. On the other hand, a three-phase power supply only works through three wires, including three-conductor wires and a neutral wire.

Thus, the costs of cabling and total installation are both reduced when you deliver three-phase power directly to your server cabinets.


In a single-phase power supply, it only suffices to 230V, whereas a three-phase power supply maximizes up to 415V.'

Its place of utility

Residential homes usually utilize lower power supply, requiring less quantity of power to function your mobile devices and home appliances. In contrast, commercial and industrial companies require heavier electronic load. Hence, it utilizes a three-phase power supply to function.


A single-phase power cannot start by themselves, requiring external devices such as Motor Startups. As its opposite, a three-phase power can start by itself without requiring any external devices. Also, it can even reverse the directions of two conductors.


A single-phase power supply generates a lower amount of electricity to support homes and non-industrial businesses, whereas a three-phase power supplies power grids, data centers, aircraft, shipboard, and other electronic loads larger than 1,000 watts.

Now, it is time for you to choose. What is your choice?

To sum up everything, choosing between a single-phase power or a three-phase power is a question of your necessity, economy, and practicality. While you benefit from these two power supplies, always consider your practical need.

For a real-life application, Circuit Specialist suggests you choose a single-phase power for domestic and residential use.

A single-phase power has simple and ordinary physical features, requiring a small amount of power to function your mobile devices and home appliances.

But, when you have a three to four air conditioning units running at the same time, double door refrigerators, supersize washing machines, then Circuit Specialist advises you to avail a three-phase power supply to distribute each load properly.

Nevertheless, while both single-phase and three-phase powers have palpable differences, you should always consider the following factors to have a wise investment:

  • required wirings on power supply;

  • voltages;

  • its place of utility;

  • efficiency of performance; and

  • application.

Source: roboticsandautomationnews.com