How to Wire 3-Phase Power in Your Garage

Having 3-phase power in your garage can be extremely useful if you want to run heavy machinery or high power tools. However, wiring a garage for 3-phase power is a complex job that requires knowledge of electrical systems and codes. This guide will walk you through the entire process of wiring 3-phase power in your garage step-by-step.

Understanding 3-Phase Power

3-phase power utilizes three separate 120 volt hot wires, each shifted 120 degrees out of phase with each other. This creates 3 separate 120 volt phases, resulting in 208 volts between any two power wires and 240 volts if you combine all three.

The key advantages of 3-phase power are:

Determining Your 3-Phase Power Needs

Before wiring for 3-phase, you need to determine the power requirements for your garage. Consider the following:

Working with an Electrician

Electrical work should only be done by a licensed electrician. Improper 3-phase wiring is extremely dangerous and can cause fires, injury, or death.

When hiring an electrician:

Electrical Service Requirements

To wire your garage for 3-phase power, you'll first need to have adequate electrical service coming to the building. Key requirements include:

If your existing electrical service doesn't meet these requirements, upgrades will be needed first before proceeding.

Running 3-Phase Wiring

Once your service is ready, your electrician can run the necessary 3-phase wiring. Key steps include:

Installing the 3-Phase Breakers

Your electrician will install the necessary 240V breakers in the new subpanel:

Running the Final Circuit Wiring

The last step is running wiring from the subpanel to your final loads and outlets:

Once all connections are made securely, your electrician will verify proper functioning and make any final adjustments needed. Your garage will then be wired for full 3-phase power.

Safety Tips

When working with 3-phase power, crucial safety tips include:


Wiring a garage for 3-phase power takes careful planning and should only be done by qualified electricians. When sized properly and installed correctly, a 3-phase system provides the heavy duty power needed for serious DIYers and hobbyists. Follow the code requirements and safety tips outlined here closely to ensure you have a safe, high capacity electrical system powering your garage workshop.