Best Trailer Wire: Specification and Guide to Wiring Trailer

Trailer wire is a type of electrical wire designed to connect the electrical system of a trailer to that of a towing vehicle, thus ensuring the proper operation of both vehicles. Typically, trailer wires consist of stranded copper wires that are each wrapped in a unique color of PVC insulation, with a PVC sheath serving as the outer layer. Additionally, it can operate at temperatures as low as -20 degrees Celsius and is characterized by softness, durability, and friction resistance.

The trailer cable wire is mainly used for caravan trailer use, and it connects the various electrical components and lights on the vehicle. It should be used with care for safety and proper connection. Now, let’s talk about the trailer wire gauge first.

What gauge is trailer wire?

The trailer wires carrying capacity and the length of the wiring determine the trailer cable size. It ensures that the proper trailer wire s gauge is being used in order to ensure proper vehicle operation. Trailer wiring generally uses 16 gauge wire, but it may be recommended to use a larger gauge wire for longer trailers, such as 14 gauge. Let’s check the trailer wire size chart below.

Suggested Trailer Wire GaugeColorFunctionWhere to connect
(vehicle side)
Where to connect
(trailer side)
14GreenThe right signal lightsWires for right turnTrailer’s right turn signal
14YellowThe left signal lightsWires for left turnTrailer’s left turn signal
14BrownTail lightsHarness for tail lightsTrailer’s tail lights
10BlueBrake powerElectric brake control powerTrailer’s brake lights
10RedBattery hot leadFuse block or fused battery leadbattery charger
14BlackBattery hot leadBack-up circuitBack-up lights
10WhiteGround wireVehicle ground wiresTrailer’s ground wires

A standard for wire gauge is established by the American Wire Gauge (AWG) system; the lower the number, the thicker the wire. 16-gauge wire is commonly suggested for trailer light wiring in 4-pin or 5-pin harnesses, and 7 way trailer wire may be used 14 gauge trailer wire.

7 way trailer wire
7 Way Trailer Wire

7 way trailer wire is flexible cable used to contacting trailer  vehicle. 7 core trailer wire consists of seven wires that are color-coded to match the functions they control.

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After knowing the trailer wires size, we also need to learn the trailer wires colors next.

Trailer wire colors

For better trailer wiring, each conductor of the trailer cable uses different colors to distinguish its use. They are usually 2 wire trailer wire, 4-way trailer wire5 core trailer wire and 7 core trailer wire. Below are the functions of the colors normally used.

trailer wire

Brown: trailer light wire, usually used for tail lights, including running lights, number plate lights and marker lights.

Yellow: turn the signal and brake light on the left.

Green: for the right turn signal and right brake light.

White: trailer ground wire. It connects the trailer to the electrical system of the towing vehicle and is used for earthing to protect the vehicle.

Blue: brake wire for trailer, used for the electric trailer braking system. This wire connects the trailer’s braking system to the tractor’s brake controller.

Black: used for the battery of the caravan.

Red: the red wire is used for auxiliary power or additional lighting functions.

After introducing these typical colors, then let’s examine the trailer wiring.

How to wire a trailer?

To help people make the use of trailer wiring cable easier and to correctly connect the electrical components between the trailer and the towing vehicle, a detailed list of steps is given below. Of course, one needs to be skilled in the wiring system of the vehicle before wiring the trailer.

Step 1: Prepare the required items in advance, such as the trailer wire connector, trailer wiring harness and various hardware.

Step 2: Check the trailer wires and distinguish the purpose of the various colored wires to facilitate proper connection afterward.

Step 3: Strip the insulation from both ends of the trailer wires and connect each one safely and securely to the corresponding function.

Step 4: Once the connections are completed, check the functioning of the connected wires.

Step 5: Protect the wire joints during use to keep them from being damaged.

trailer wiring

Finally, if it still needs to be clarified about trailer wire hookup, or if the construction of the vehicle is different to cause wiring differences, you can refer to the trailer wire color code or seek the help of a professional electrician.

If you still want to know more details clearly, please check the trailer 7 wire diagram. Then we can analyze the trailer lights wire specifically below.

How to wire trailer lights?

Trailer lights consist of tail lights, brake lights, turn signals, and brake lights, among other lights. Here are the detailed steps for wiring trailer lights.

Step 1: Prepare the necessary tools for wiring, trailer cable wire connector, trailer wire, wire stripping tool, tape and circuit tester etc.

Step 2: Consult the trailer manual and wiring diagram to familiarise yourself with the vehicle construction and the function of the wires.

Step 3: Connect the wires to the connector with the matching function on the connector.

Step 4: Test the wiring with tools for correctness and safety.

Step 5: Secure the trailer wiring harness with tape.

wiring trailer lights

These are the specific steps for wiring the trailer lights, let’s look at how to wire the trailer plugs.

How to wire trailer plug?

Trailer plug wiring refers to connecting the trailer’s plug to the tractor’s power supply. Detailed steps on how to wire trailer plugs are provided below.

Step 1: Prepare the necessary wiring tools. Prepare the necessary wiring tools, such as the trailer plug, wire harness and trailer wiring kit.

Step 2: Identify the trailer plugs. The most common are 4 way trailer wire plug and 7 wire trailer plug.

Step 3: Familiarize yourself with the pin layout of the trailer plug; refer to the wiring diagram for details.

Step 4: Remove the insulation from the trailer cable wire connectors and connect all the wires together.

Step 5: Conduct a test to see if the connections are correct.

Step 6: Use electrical tape to secure the wires.

trailer wire plug

Be sure to pay attention to safety and proper installation during the wiring process, and consult a professional if necessary. And then what type of electrical wires do you need for brake lights? Come along and explore it.

What kind of electrical wires do you need for a brake light?

Brake lights are important for trailers, and when they come on while driving, they are meant to inform following cars and pedestrians to stop and take care. Ensure that the brake lights are functional. Then one usually needs to use wires that can handle the electrical load and provide reliable power transmission. The electrical load that a wire can support increases with thickness. Normally, 16 and 14 gauge trailer wire is sufficient for the brake lights to operate properly. In special cases, to maintain smooth electrical transmission, the size of the wire may be increased or decreased.

Trailer wires are often used outdoors, so it is important to choose wires specifically for trailers in brake light wires, as these are produced specifically for cars, and the different colors have special functions to make it easy to distinguish them. In addition, it is important that the trailer cable purchased complies with local production regulations and electrical standards.


This is what you need to know about trailer wire near me, trailer wire gauge, colors, how to wire the trailer, lights and plugs, and which trailer cable wire to use for the brake lights. After reading this, people have a better understanding of all trailer cables. When you need to do trailer wiring in your life, you will follow the steps to do the wiring.

Moreover, if you don’t have a trailer wire for sale near where you live, you can ask ZW Cable, which produces professional trailer wires for you to choose from.

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About Me
Richard Zi
Richard Zi

My name is Richard Zi, and serve as the General Manager of ZW Cable. With a deep and extensive background of more than 15 years in the cable industry, I am excited to share my wealth of knowledge and experience.ZW Cable is a renowned company in the field of cable manufacturing in world, we specialize in selecting the best cable sizes and effectively solving all your cable challenges. If you have any questions or needs regarding cable solutions, please contact me and I assure you of the highest standards of personalized and effective guidance and support.View All My Posts >>

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