How to connect a transformer from 480v to 120v? (Solved) - Wiring Solver (2023)

Core items:

  • It is necessary to correctly identify the transformer terminals, as well as the input and output.
  • For the correct functioning of the transformer, the terminals must be wired accordingly.
  • It is highly recommended to wear safety equipment such as rubber boots and gloves to avoid any kind of electrical hazard.

There may be many different voltage and rating power supplies in a home, depending on the specifications of the home and region. Similarly, devices of different calibers often require different power sources to function properly.

In order to use a higher voltage power supply to run an electrical device (fans, lights, blender, etc.) we must first reduce the voltage of the source. This can be done with a step-down transformer. There are several steps you need to follow to know how to connect a 480v transformer to 120v.

There are a few steps to properly wiring a transformer. They are as follows: assemble the necessary equipment, turn off the power, identify the terminals on the switch, connect the wires to the transformer and troubleshoot.

In this article, I go into each stage in detail to ensure you fully understand the process. Let's start then.

(Video) transformer connections

How to connect a transformer from 480v to 120v? (Solved) - Wiring Solver (1)

How do I wire a 480v transformer to 120v?

There are a few steps to properly wiring a transformer. They are:

1. Gathering the necessary tools and equipment

Before proceeding with the installation steps, it is recommended that you acquire certain tools to successfully complete the task and keep you safe.

You should always wear safety gear before working on electrical components. Even with tasks like finding outHow to connect the generator to the houseand others, you must wear gloves, boots, and goggles, as well as the necessary tools to complete the process.

What equipment do I need?

  1. First you need to buy rubber boots and gloves. This will prevent accidental contact with live wires.
  2. You may need safety goggles to protect your eyes in the event of sparks or kickbacks.
  3. Voltmeter to check the voltage of the wires to make sure they are delivering the exact voltage you want and to verify that the power has been turned off correctly.
  4. You can use contact voltmeters or non-contact voltage testers that offer sufficient security.
  5. You should also purchase a suitable step-down transformer that will convert 480V to 120V.

2. Turn off the device

Before proceeding with wiring the transformer, you must disconnect power from the main electrical panel in your home.This is an essential step for any type of electrical installation. If you try to find outhow to connect the fan controller to the control unitÖHow to convert 3 phase to 220v single phase, you must turn off the power.

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How do I turn off the power?

  1. Locate the main switch in your home, as well as the switch that supplies power to the wires you will be working on.
  2. Once you have determined which breaker is the correct one, turn on the breaker.
  3. Check the power supply wiring with appropriate equipment to ensure that current is no longer flowing.
  4. You can use tools like an ammeter or voltmeter to see if current is still flowing after the circuit breaker has been turned off.
  5. Wear rubber boots and gloves to protect yourself adequately against hazards or electrical breakdowns.

3. Identification of transformer cables

Proper identification of a transformer's terminals is critical to knowing how to wire a 480V to 120V transformer.Because in order to properly wire the transformer, you need to know which wire to connect to which terminal.

Proper terminal identification is also a required step for single phase 480V three phase to 120V transformers.

How to connect a transformer from 480v to 120v? (Solved) - Wiring Solver (2)

How do you identify the wires in a transformer?

  1. There are two person sections of a transformer. The primary and the secondary.
  2. The primary is the input and the secondary is the output.
  3. The most common layout is shown in the diagram above (Fig. 1).
  4. The wires marked H1, H2, H3 and H4 are primary. They are usually color-coded black. This can be simplified by notating as input.
  5. The wires marked X1, X2, X3 and X4 are the secondary ones. They are usually color-coded red. This can simply be called the output of the transformer.
  6. Your 480 volt power supply should be connected to the primary.
  7. 120 volts is supplied through the secondary of the transformer.
  8. But in order to derive the appropriate conversion, we need to wire them properly.

4. Wire connection

In order for the transformer to work properly, you need to make the wire connections accurately.The wired connection is a crucial step. Any mistake in this step can cause serious accidents and electrical hazards that can result in fire or damage to electrical components.

How to connect a transformer from 480v to 120v? (Solved) - Wiring Solver (3)

Wiring a transformer

  1. Locate the H2 and H3 wires.
  2. Cover them individually with a wire lid or electrical tape.
  3. H1 and H2 are your 480 volt input. Connect them to the power supply.
  4. On the secondary, locate wires X2 and X4. Tie them together with a wire cap or electrical tape.
  5. This is the white 120 volt neutral wire from your transformer. You can connect it to the neutral wire of your device to turn it on.
  6. X1 and X3 must be connected to each other. This acts as the 120 volt black hot wire from the transformer.
  7. Connect this to the hot port on your device you wish to power.

However, before connecting the transformer, check the specific make and model of the transformer you are using. Because the primary and secondary side of the transformer can vary depending on the model. The color code can also be different.

I've chosen to follow the most common configuration for this article.

5. Troubleshooting

It is important to troubleshoot electrical components after installation to ensure they are working properly.

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Test transformer output

  1. Use a voltmeter to check the transformer output voltage.
  2. If the output voltage is 120 volts, the installation has been successfully completed.
  3. However, if the output voltage is not 120 volts, turn off the power supply and check the wiring again according to the diagram shown in the article (Fig. 2).


In this article I have discussed all the steps required to know how to connect a 480V transformer to 120V. The processes are broken down in such detail that you can carry out this activity yourself.

However, as with all electrical work, you must exercise extreme caution and take all appropriate safety precautions before beginning. To make the installation process easier and more precise, wear appropriate rubber gloves and boots and the necessary equipment. Serious accidents and electrical hazards can occur as a result of poor wiring.

How to connect a transformer from 480v to 120v? (Solved) - Wiring Solver (4)

Kristall m Editor-in-Chief
He is best known for his skill with electricity. As can be clearly seen in most of his work. His IT background also allows him to familiarize himself with other technical aspects. He has been writing here on this blog since the beginning and loves to play with his impressive writing.

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