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Single Phase vs Three Phase Generator – Which One to Pick?

Single Phase vs Three Phase Generator
Written by Jamie Masterson

The power supply system of generators is primarily categorized into two systems – single-phase and three-phase.

Single-phase is ideal when you don’t need much backup power e.g. when you run moderate loads like home appliances.

The three-phase power supply system is best for heavier loads, such as factories, industrial sites, or manufacturing units where high power consumption is required.

A Quick Look at the Single-Phase Power System

single-phase power system

Single-phase generators usually involve 2 different wires to complete the circuit – the neutral and the conductor. The conductor wire is for transmitting the current while the neutral wire works as the electrical return path.

Single-phase generators deliver an effective power source at a reasonable price tag. Most single-phase generators supply between 120 and 240 volts to power small appliances.

A Quick Look at the Three-Phase Power System

three-phase power system

Three-phase generators are ideal for industrial use and involve 4 wires, 3 conductor wires, and 1 neutral wire. The conductors are 120-degree apart from each other and out of phase. You can use the three-phase as a single-phase system by taking one phase wire and the neutral wire from your three-phase supply.

The constant three-phase system won’t totally drop the power. You can draw the power in a delta or star configuration and use the star connection for long-distance conduction since it includes neutral for the fault current. On the other hand, the delta connection does not have a neutral wire but includes three-phase wires.

You should invest in a 3-phase generator for industrial applications. Most 3-phase units come with a voltage of 480. These units may cost a bit more and require frequent maintenance, but they’re powerful enough to run power-hungry industrial machinery with unbeatable efficiency.

Single Phase vs Three Phase Generator: How They Differ

1. Power generation

  • Single-phase

As the name implies, single-phase generators use a single AC wave to generate kilowatt outputs. They only operate from 1 power line produced by a handful of conductive wires that have inconsistent output sequences. Single-phase generators may not arrange for a stable power source when compared with a 3-phase unit.

On the bright side, single-phase generators don’t entirely drop out even at their lowermost point. The low-cycle voltages remain obscure unless they’re run at overcapacity.

This is the reason you don’t see lights flickering that often. Sometimes, the flickering is so fast that it remains imperceptible to a human eye.

  • Three-phrase

The three-phase generators, on the other hand, generate power through 3 simultaneously-run current streams. This setup requires strong core voltage to achieve uninterrupted power generation.

They can maintain power for more intense applications as the 3-phase generators pattern the wires to cycle at 120º offsets.

This means that when one current cycle will be at the lowest, another cycle will be at the highest; delivering complementary wavelengths and working in tangent to deliver a stable flow of power at all times.

As an operator, you may choose to sync all 3 cycles to run a big commercial system or use each conductor wire to connect 3 smaller equipment pieces to the individual lines of the exact 3-phase unit.

Conductor Wires

The name says it all!

A single-phase needs one conductor and one neutral to complete its circuit.

Along with that, your three phases require three conductors and one neutral.

Power output

  • Single-phase

With one AC (fluctuates in between 170 to -170) flow, they are less steadier compared to the three-phase units. They produce the most power when the wave is at its peak.

It becomes difficult to produce more power with one cycle because the wave continuously keeps coming to its lowest point.

Now comes the wonder of a single phase. Your eyes won’t be able to notice the light flickering because even at the wave’s lowest point they don’t fully give up unless they are overloaded.

  • Three-phase

Interestingly, one of the three AC (120 degrees) flows is always at peak for a stable supply of electricity. They can bear heavy and extra loads smoothly.


  • Single-phase

Single-phase has one current flow so there is no scope of using them for different purposes. They only operate from 1 power line produced by a handful of conductive wires that have inconsistent output sequences.

Single-phase generators might not provide a stable power source when compared to a 3-phase unit.

  • Three-phase

Imagine you have the authority to customize the power distribution according to the requirements of factories or devices.

Suppose your large industrial equipment needs the power of all the three electricity produced within the generator, you can make it happen.

Again, the skyscraper’s elevator and office equipment can get individual electricity from one 3-phase generator.

Power factor

Here, 3-phase is the winner because they have a 0.8 (Highest is 1) power factor rating which is 1.5 times higher than a single phase within the same size and weight. They provide the idea of how much AC power your generator can supply.

When to Choose a Single-Phase Generator?

  • For residential use
  • Individual computer/laptop/television/modem
  • Backup Generator

When to Choose a three-phase generator?

  • Advanced Industrial production Equipment especially for regular manufacturing
  • Large Electronic systems (Commercial refrigerators, Conveyor systems, heavy load engines, electric broilers, and many other electronic types of equipment
  • Central cooling/heating system of high rise buildings
  • Air ventilation system of commercial spaces
  • Commercial and large Food storage
  • Multi-story building/tower and skyscrapers (elevator, Office suite)
  • Cloud-based data storage centers

Pros of single-phase generators

  • The purchasing cost is low
  • They use less conductive material comparatively

Cons of single-phase generators

  • They are more prone to voltage disruption
  • Higher maintenance cost
  • Cannot support large scale need
  • Less efficient
  • Failure of one conductor will shut down the whole generator

Pros of Three-phase generator

  • 180% more capacity than single phase
  • Savior for industries
  • Minimum or accidental voltage disruption only
  • Few mechanical vibrations with stable power connection
  • Reliable for large-scale industrial operation

Cons of the three-phase generator

  • Uses more winding and wiring
  • The purchasing cost is higher


Q. Can I power my house with a 3-phase generator?

You can but first ensure that you are going to use three phases equally. Do not make one or two of them sitting ideally because the generator will get damaged eventually for an unbalanced load.

Q. Is it harmful to use only one phase of a three-phase generator?

No, it is not harmful if you use it temporarily but if you do it frequently then your generator will go into distress. Besides, never overload them e.g. if one phase supplies 20 A then you shouldn’t exceed 20 A.

Better buy a single-phase generator that will be cost-effective for you.

Q. Is a 3-phase generator better than a single-phase one?

Three-phase produces better power flow than single-phase because they create three separate waves and one of them is always at its peak ensuring continuous heavy power supply.

Even if one conductor is out of order the other two will do the job so a three-phase will not shut down completely at once but a single phase has the risk.

However, three phases are for industrial use and the household doesn’t need them much. So they are both useful in their particular sector.

Q. What is “phase” in electricity?

Generally, it is the voltage/current in a conductor or neutral wire. Phase means the distribution of load. For instance, the additional load is carried through a single wire in a single wire connection; but when you use 2 wires, the loads will be distributed between them.

So, single-phase or 1-phase systems involve 2 wires (1 conductor + 1 neutral) and 3-phase systems involve 4 wires (3 conductors + 1 neutral).

Q. Is 3-phase cheaper than single-phase?

Technically yes. 3-phase power systems are more within your means than single-phase systems. Besides, they’re more efficient and offer a safer connection model. Sure, they’ll cost you more in the beginning, but pay off in the long run.

About the author

Jamie Masterson

With decade-long experience as a generator technician, Jamie has worked with USA’s top generator manufacturers and suppliers as an independent contractor.

The long years of service to the industry has taught Jamie the ins and outs of troubleshooting, repairing, and maintaining all kinds of generators in home, industrial and outdoor settings.

Jamie thinks this platform is a great opportunity to share his tips and tricks with you so you can make the most of such power equipment for better living.

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