How To Convert AC 3-Phase To AC Single Phase Outlet (120v, 220V And 240v Power)

When you want to use a different load on the electric structure for your welding projects, you have to convert the system to a different one. Most of the time, you might be concerned with converting a three-phase structure to a single-phase structure.

Do you know how to do that?

Don’t worry; I am here to get you through the whole thing. I will tell you how to convert three phase ac power to single phase 120v, 220v and even more. So, if you are working with something similar and need to know how to convert these electric structures, this is the place to be.

Without wasting any more of your time, let’s get right into it.

Convert 3 phase to single phase circuit
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Before you move further and see how to convert them, you should know about them a little bit. This will give you the idea of why you should be using one or the other in the first place.

What Is 3-Phase Circuit?

The simplest way to describe this is through wires. A three-phase electric power comes with three wires. Think of it like an engine with three compartments and three rotating pistons to power the system.

Three phase Circuit
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You get to see a 3-phase electric system in most commercial buildings. There are typically four wires in total; three are live wires, and the last one is a neutral wire. For a lower power load, you can do 120-volt. As for higher power load going with 208-volts is a pretty safe option.

Welders with 3 pin runs in this circuit. Generators of such welder is made compatible to 3 phase electric circuit. You need to specially design the circuit with the help of electrician if you want to run 3phase welder at home, because most of the home lacks 3 phase system in circuit board.

What is a single phase Circuit?  

When it comes to single-phase power, the easiest to understand the concept is the bicycle. On a bicycle, you are using one leg at a time for rotating the pedal, and the other one stays neutral. That’s how it runs.

single phase Circuit
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Similarly, the one-phase power consists of two wires in general. One is a live wire, and the other is a neutral wire. Current usually flows at constant rate between these wires alternatively to produce power. You will get to see this system mostly in residential electrical circuits. The voltage varies from place to place.

In the USA, it’s 120-volts primarily for this system. You can run one phase welder machines in that electric wire system. You can’t use multi phase with this circuit.

Can You Convert three-Phase To Single Phase For Welding Machine?

Absolutely, the transformation from a 3-phase to a one-phase system is a feasible endeavor. To accomplish this, a phase converter or a dedicated transformer can be employed. A phase converter works by generating a synthetic third phase, allowing the conversion from three-phase power to one-phase.

Alternatively, a dedicated transformer can be used to isolate and reconfigure the electrical supply of power. This conversion is often sought in scenarios where machinery or equipment originally designed for a 3-phase power source needs adaptation for use in locations with single-phase ac power infrastructure.

How To Convert 3-Phase To Single Phase (120v, 220v & 240v) Power

Converting a 3-phase system to a single-phase 220v power, 240v or 120v power involves a few steps and the use of appropriate equipment. Here’s a general guide on how to do it:

  1. Assessment: Confirm that the equipment or machinery you intend to power with one-phase 120v, 220V or 240v whatever power you are using, is compatible and designed for this voltage.
  2. Consult an Electrician: Before proceeding, it’s essential to consult with a qualified electrician. Electrical work requires expertise to ensure safety and compliance with local electrical codes.
  3. Phase Converter: One common method for converting 3-phase to single-phase is by using a phase converter. There are static converters and rotary converters available. The type of converter you choose depends on your specific needs and the characteristics of your 3-phase system.
    • Static Converter: A static phase converter is a simple and cost-effective solution for light to moderate loads. It uses capacitors to create a third phase, allowing the one phase motor or equipment to operate on single-phase power.
    • Rotary Converter: A rotary phase converter is a more sophisticated option suitable for heavier loads. It utilizes a spinning motor generator to generate a balanced single-phase output.
  4. Installation: Follow the manufacturer’s instructions for installing the chosen phase converter. Installation may involve connecting the converter to the three-phase power source and wiring it to the equipment that requires one-phase power.
  5. Verify Compatibility: Ensure that the equipment connected to the converted power supply is compatible with single-phase 120v, 220V or 240v power. Some motors and devices may require additional adjustments or modifications.
  6. Testing: After installation, conduct thorough testing to confirm that the converted power supply meets the requirements of the connected equipment. Check for proper voltage levels, phase balance, and overall performance.
  7. Compliance: Always adhere to local electrical codes and regulations. If you are unsure about any aspect of the installation, consult with a licensed electrician to ensure safety and compliance.

It’s crucial to emphasize that electrical work should be carried out by qualified professionals.

Methods Of Converting 3 Phase To Single Phase Circuit

Let’s check out the methods you can use for converting 3-phase to one phase.

1. Using A Neutral Wire

This is the easiest and quickest method for converting a 3-phase system to a single-phase system. All you are doing here is, ignoring the two phases in your 3-phase system and using only one of them.

If it’s a four-wire system, you are using a neutral wire and a live wire while keeping the other two live wires unoccupied. However, this method won’t give you the most accurate results in the conversion. So, it works well for projects that don’t require too much accuracy.

2. Phase Converter Method

If you need to convert power for only one device or motor, you can simply use the phase converter for that.

You have to get two wires from your motor then run them through the converter. And then, run the converter through the power supply.

Finally, you have to use the wires that have their ends stripped and attach their inputs to the other outputs for converting the system.

Other than these two methods, you can use different transformers like open delta transformers or Scott T transformers, or even Le-Blanc transformers to get the job done.

How to Convert 415v 3 phase to 230v single phase

It’s quite easy to convert a 415V 3-phase to a 230V single phase because it’s more like a natural conversion. Typically, when you convert a 3-phase to a 1-phase electric system, you will lose some voltage from that conversion.

In this case, when you convert a 415v 3-phase system to a single-phase system, the voltage goes down to 230V. The reduction in the voltage is measured by dividing the 3-phase voltage by root 3 or 1.71.

Here’s how you can convert the system –

  • You can simply tap off one phase from the three phases and use that along with the neutral one to get the desired voltage on a single phase. Before you go ahead and do this, make sure to know wire sizes, switches, fusing, safety interlocks, and so forth.
  • Another method is getting a one phase transformer that converts a 415v 3-phase system to a 230v single-phase system.
  • You can also take the neutral wire and any wire from the three phases to create your 1-phase system. The voltage output will automatically come down to 230v.

These are 3 ways you can get a 230v single phase from a 415v 3-phase system.

What Projects Can Be Done With A Single Phase

Single-phase electric system is the kind of system that provides you decent power to use different electrical appliances. As we are talking about welding applications in single phase system, it is good for doing low power welding tasks.

For example, doing home welding, welding trailers, exhaust pipes and thin metal to metal. It’s a good source for things that require a low amount of power.

So, whenever you are working with projects that require a small amount of power you can use the single-phase system to power it up. Projects like making an electric circuit to power up a device can be a good example of this.

In short, the projects that you would usually do for different science fairs and stuff.

What Projects Can Be Done With 3-Phase

Compared to the 1-phase electrical system, the 3-phase system provides a lot of power. It’s used for commercial purposes for powering items that require a high level of power. Or you can also power a lot of items that a single-phase system can’t cover.

The welding projects you can do with a 3-phase system lean more towards the commercial sectors. Anything requiring a lot of electrical power will use the 3-phase electrical system. For example, welding thick metals, welding in ship, car engines, grills, railroad tracks etc. projects where you need more power.

Is There Any Risk Of Casualty While Converting 3 to 1 Phase?

There aren’t many risks involved with converting a 3-phase system to a 1-phase system. Doing the opposite might have some risks as you will be taking the lower power system to a higher power load.

Converting your 3-phase system to a single-phase system can be beneficial, especially when you are not using the higher power supply. The 1-phase system works quite well with lower horsepower systems and lighter electricity use.

What is the formula for single phase voltage?

The formula for calculating single-phase voltage (V) in a system where you know the power (P) and current (I) is:



  • V is the power in volts,
  • P is the power in kilowatts, and
  • I is the current (measured in amperes).

What is the 3-phase voltage formula?

The formula for calculating three-phase voltage (V) in a system where you know the power (P) and the square root of 3 (1.732) is

V= P/ (I×1.732​)


  • V is the voltage,
  • P is the power (measured in watts),
  • I is the current (measured in amperes)

What is the formula for 3 phase current?

The formula for calculating three-phase current (I) in a system where you know the power (P), voltage (V), and the square root of 3 (1.732​) is:

I= P/V×1.732​


  • I is the current (measured in amperes),
  • P is the power (measured in watts),
  • V is the voltage, and
  • 1.732​ is the square root of 3

This formula is derived from the basic electrical power equation P=1.732×V×I, which can be rearranged to solve for current (I) as I=P/(V×1.732)​ in a three-phase power system.

Frequently Asked Questions (FAQ)

1. Can You Get 240v Single Phase From 3 Phase?

Certainly, obtaining a 240V single-phase supply from a 3-phase system is feasible through a process known as phase-to-neutral connection. In this method, one of the phases is selected and connected to the neutral wire, effectively creating a one phase output.
This technique is commonly employed in situations where equipment or appliances require a 1 phase power source, yet the overall electrical system is three-phase.

2. How Do You Calculate 3-phase To Single Phase Voltage?

Calculating the conversion from 3-phase to single-phase voltage involves a straightforward yet crucial process. In a 3-phase system, the line-to-line voltage (VL-L) is √3 times the phase-to-neutral voltage (VL-N).
To derive the single-phase voltage (V single), you simply divide the line-to-line voltage by √3. The formula is V single = VL-L / √3.

3. What is a 220V converter?

A 220V converter is a device designed to modify electrical voltage from one level to another, specifically catering to the conversion of 220 volts. This device serves as a bridge, facilitating seamless electrical connectivity and safeguarding appliances from potential damage due to incompatible voltage levels.

4. Is 220V single-phase or 3-phase?

A standard 220V supply is typically associated with single-phase power. In residential and most commercial settings, single-phase power systems are common, and 220V is commonly used for various applications such as household appliances and lighting.
On the other hand, 3-phase power systems usually involve higher voltages, such as 208V or 480V. If you encounter 220V in a standard domestic or small-scale commercial environment, it is most likely part of a single-phase electrical system.

5. What is the difference between 220 and 220 3-phase?

The primary difference between 220V and 220V 3-phase lies in the common type of electrical system and the configuration of the power supply.
The 220V Single-Phase is a standard household voltage in many regions. It represents a single-phase power supply, typically used for residential purposes.
While 220V 3-Phase voltage level is not a standard configuration for 3-phase power systems. Common 3-phase voltages include 208V or 480V. If you encounter 220V in a 3-phase context, it might be measured between two phase conductors, representing a line-to-line voltage.

6. How many wires is 220v & 240 single phase?

A 240V single-phase electrical system typically consists of two wires: one hot wire and one neutral wire.

Last Words

To sum up, now that you know how to convert a 3-phase to a single-phase, you shouldn’t come across too many problems. But like I said earlier, having the basic knowledge of electrical circuits is important to convert and use these systems.

If you don’t have that knowledge base, then don’t try messing with electrical circuits. Things can quickly go wrong and cause issues for you.

Having said that, if you are not using a 3-phase system or don’t feel the necessity of it, you can always convert that to a single-phase option. Knowing how to do it is always handy knowledge to have. 

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