Why Do Brushless Motors Have 3 Wires? [Explained!]

Brushless motors have become increasingly popular because of their efficiency, reliability, and durability. Unlike traditional brushed motors that rely on physical brushes for commutation, brushless motors use electronic controllers for precise control.

Three wires (red (A), blue (B), and yellow (C)) control the 3-phases. The red wire carries current to one stator phase, the blue to another, and the yellow wire completes the circuit for the third phase. This coordinated current distribution generates the required magnetic fields for rotation.


Brushless motors utilize electronic commutation to control the flow of current in the stator windings. The electronic controller, often referred to as an ESC (Electronic Speed Controller), determines the timing and sequence of current switching to energize the windings. This precise control enables the motor to rotate smoothly and efficiently.

The three wires found in brushless motors serve specific functions in the motor’s operation. These wires are typically color-coded, with each wire having its designated role. As previously mentioned, the three common wire colors are usually red, blue, and yellow, although variations can occur. Let’s look at each wire and what it usually does.

Phase A (Red wire)

This wire carries the current to one phase of the stator windings. It connects to one of the three phases of the motor.

Phase B (Blue wire)

Similarly, the blue wire carries current to another phase of the stator windings, completing the connection to the second phase.

Phase C (Yellow wire)

The yellow wire completes the circuit by delivering the current to the third and final phase of the stator windings.

These three wires work in harmony, they don’t all fire off at the same time. This ensures the proper distribution of current throughout the motor’s windings, ‌generating the required magnetic fields for rotation.

Brushless Motor Wire Functions

Now that we understand the basic role of each wire, let’s explore their specific functions in brushless motors.

Power Supply

The three wires serve as the power supply for the motor. The ESC connects to an external power source, typically a battery, which supplies direct current (DC) voltage to the motor through these wires.

Signal Transmission

Besides carrying power, the wires also transmit control signals between the ESC and the motor. These signals inform the motor about the required speed, direction, and other control parameters.

Motor Phases

The three wires connect to the respective phases of the motor’s stator windings. By energizing the windings in a specific sequence, the motor can generate a rotating magnetic field, resulting in smooth rotation.

Brushless Motor Misconceptions

It’s essential to address some common misconceptions about brushless motors and their wiring:


The three wires in brushless motors are not typically used for grounding. The motor casing, or a separate grounding wire, is usually employed for grounding.

Voltage Regulation

The voltage supplied to brushless motors is regulated by the ESC. The wires themselves do not control or regulate the voltage.

Wire Interchangeability

While the wire colors mentioned (red, blue, and yellow) are common, it’s crucial to consult the motor’s documentation or datasheet for accurate wire identification. Wire colors can vary between manufacturers or motor models.

What Are Brushless Motors?

A brushless motor is a type of electric motor that operates without the use of brushes and a commutator. Instead, it relies on electronic commutation to control the flow of current and generate rotational motion. This design eliminates the need for physical contact between moving parts, resulting in improved efficiency and reduced wear and tear.

Speaking of Brushless motors, there is also another type of motor popular in the RC hobby called Brushed motors. I highly recommend checking out this guide where I explain the difference between brushed and brushless motors in detail.

Brushless Motor Working Principle

The working principle of brushless motors involves the interaction between the stator and the rotor. When an electric current is supplied to the stator windings, the magnetic field generated induces a magnetic force on the permanent magnets of the rotor. This force causes the rotor to align itself with the stator’s magnetic field, producing rotational motion.

To achieve continuous rotation, the electronic controller switches the current flow in the stator windings based on the rotor’s position.

Advantages of Brushless Motors

Brushless motors offer higher efficiency compared to brushed motors. The absence of brushes eliminates the energy losses and friction associated with brush contact, resulting in improved energy conversion.

Brushless motors are known for their enhanced reliability and durability because of the absence of physical brushes, which are prone to wear and require frequent maintenance.

Brushless motors provide precise control and speed regulation, making them suitable for applications where accuracy and responsiveness are critical. But while thinking about these motors, you might also wonder if they lose power with time. Check out this guide to know more: Do Brushless RC Motors Lose Power Over Time?

Applications of Brushless Motors

A brushless motor used in drones and RC planes

Brushless motors find application in various industries and devices because of their many advantages. Some common applications include the following.

  • Electric vehicles (EVs) and hybrid vehicles (HV).
  • Drones and other aerial vehicles.
  • Robotics and industrial automation.
  • HVAC systems.
  • Computer cooling fans.
  • Power tools.
  • Model airplanes and boats.

The efficiency, reliability, and precise control of brushless motors make them a popular choice in these and many other fields.

Can I Interchange The Wire Connections In A Brushless Motor?

No, you should not interchange the wire connections in a brushless motor. Each wire is designated for a specific phase of the stator windings, and swapping the connections can result in improper operation or damage to the motor.

Are Brushless Motors More Efficient Than Brushed Motors?

Yes, brushless motors are generally more efficient than brushed motors. The absence of brushes reduces friction and energy losses, resulting in improved efficiency and better overall performance.

Do Brushless Motors Require Maintenance?

Maintenance for brushless motors is minimal compared to brushed motors. It involves regular cleaning to remove dirt and debris, inspecting and lubricating the bearings if necessary, checking the wiring and connections for any damage, ensuring proper cooling by keeping the cooling system clean and unobstructed, and periodically calibrating the electronic speed controller (ESC).

Still, I think you should read this guide where I list the most common reasons why brushless RC motors fail. If you read it, you’ll know exactly what to expect and how to deal with the problems better.

Why Are Brushless Motors More Expensive Than Brushed Motors?

Brushless motors are more expensive than brushed motors because of their advanced design, electronic components, and higher manufacturing costs. However, the price difference is often justified by the superior performance and durability of brushless motors.

I also think you should check out this guide to see if brushless RC motors burn out or not. It will tell you how long these motors usually last and how to keep them from burning out.


Brushless motors have three wires to facilitate the proper functioning of the motor and enable precise control over its operation. These wires play a vital role in carrying current, transmitting control signals, and energizing the motor’s stator windings.

By eliminating physical brushes and implementing electronic commutation, brushless motors offer improved efficiency, reliability, and durability.

The three wires, often color-coded as red, blue, and yellow, serve distinct functions in the motor’s operation. They deliver power from the ESC to the motor, transmit control signals, and connect to the different phases of the stator windings.

The applications of brushless motors span a wide range of industries and devices. They power electric and hybrid vehicles, enable precise control in drones and robotics, contribute to efficient HVAC systems, facilitate cooling in computers, enhance the performance of power tools, and find use in model airplanes and boats, among many other things.

I hope you found this article helpful, you may find the following article to be of interest: What Does KV Mean In RC Motors? 4 Essential Insights!

Paul Good

This awesome hobby has something for everyone, whether you like to build your RC from scratch and keep modifying till you've got it to just how you want it, to track racing. You might be out with a boat, or perfecting your skills with a plane. Are you taking some cool pics with your drone? I'm sure my site will help you on your journey.

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