What is trailer cables?
A trailer cable is a cable used to connect a tractor to a semi-trailer. Its main purpose is to control the trailer’s turn signals, brake lights, tail lights, fog lights, and other lighting. Some special trailer cables are also used for connecting trailers to commercial and agricultural vehicles. These cables are divided into two types: spiral cables and straight cables.
A trailer cable with excellent electrical performance, oil resistance, high-temperature resistance, and low-temperature resistance can ensure safe driving for truck drivers over nearly 100,000 kilometers.
Working Principle of Trailer Cables
Trailer cables are typically multi-core cables, with common configurations including 4-core,5 Core, 7-core, 13-core, and 15-core. Each core wire controls a specific lighting or signal function on the trailer. The following are common trailer lighting control wiring specifications based on the SAE J560 standard in the United States:
| Contact No. | Function | Cross-sectional area | Core Wire Color |
| 1 | Ground return to towing vehicle | 8awg 8mm2 | White |
| 2 | Clearance side marker and identification lamps | 12awg 3mm2 | Black |
| 3 | Left turn signal and hazard lamps | 12awg 3mm2 | Yellow |
| 4 | Stop lamps and anti-lock braking system | 10awg 5mm2 | Red |
| 5 | Right turn signal and hazard lamps | 12awg 3mm2 | Green |
| 6 | Tail and license plate clearance and or side marker lamps | 12awg 3mm2 | Brown |
| 7 | Continuous ABS Primary power/(auxiliary device) | 10awg 5mm2 | Blue |
Common standards for trailer cables include ISO 1724, ISO 1185, ISO 11446, etc. Learn more trailer wiring diagram check this blog.
Components of trailer cables
Conductor
Pure copper conductors are preferred. Although copper-clad aluminum conductors are available on the market, they have unstable signal transmission and poor durability, and although they are cheaper, they are not recommended for use.
Insulation
Common materials include PE (polyethylene) or PVC.PE insulation offers superior electrical performance.
PVC insulation is more economical and has acceptable performance.
Sheath
Common materials include PUR, PVC, and TPE:PUR is the recommended first choice, offering advantages such as wear resistance, high mechanical performance, resistance to high and low temperatures, UV resistance, and hydrolysis resistance. It is particularly suitable for spiral cables, offering good elasticity and tear strength, and remains flexible at low temperatures, making it ideal for agricultural trailers and commercial trucks.
PVC is inferior to PUR in performance but is cost-effective and suitable for light-duty applications such as campers.
TPE is soft and suitable for outdoor environments but has lower mechanical properties than PUR.
Shape
Trailer cables come in two forms: straight and spiral. Spiral cables are superior in high-demand scenarios due to their convenience, safety, and durability.
Common Types and Applications
By Conductor Number
2-3 cores: Agricultural trailers, fire trucks, military vehicles.
7 cores: Commonly used in RVs and standard trailers.
15 cores: High-end commercial truck trailers supporting advanced features like EBS.
By Material
PUR trailer cables: Preferred for commercial trailers.
PVC trailer cables: Suitable for consumer-oriented trailers.
Main Application Industries
Agriculture, transportation, outdoor camping, etc.
Key Factors to Consider When Purchasing Trailer Cable
Performance Requirements
Capable of maintaining flexibility and stable signal transmission under long-distance transportation and extreme climate conditions (e.g., low-temperature environments in Russia and Canada).Compliance certifications
Includes ISO, SAE, RoHS, CE, and other certifications to ensure product quality and regulatory compliance.Customization capabilities
Whether customization of length, core count, core wire color, jacket material, and connector type is supported.Bulk supply capabilities
Due to the complex production process of spiral cables and the scarcity of experienced workers, stable bulk supply and timely delivery capabilities are key procurement considerations.
Application Cases
A Canadian trailer company previously used PVC-material trailer cables, but low temperatures in winter caused the cables to harden and frequently break, resulting in vehicle downtime and logistics disruptions, severely impacting the company’s reputation and revenue.
To address the issue, KMCABLE provided special trailer cables capable of withstanding temperatures as low as -55°C. These cables remain flexible and perform stably even at low temperatures. Since their adoption in 2022, the customer’s market share has significantly increased.
Summary
As the “lifeblood” of a trailer’s electrical system, trailer cables play a critical role in signal transmission and power supply. With ISO and SAE certifications, along with robust customization and bulk supply capabilities, KMCABLE has established itself as a leading manufacturer of trailer cables in the industry.
If you are seeking a reliable supplier of trailer cables, please contact us to request samples and quotes!
