Electrical coils
Spiral cables are an indispensable part of truck and trailer electrics. They form the flexible, self-retracting connection between the tractor unit and the trailer, carrying responsibility for the correct functioning of lighting, electronic braking systems, auxiliary power supply and high-current charging circuits. For trailer builders, body builders, truck workshops and transport companies operating their own workshop, selecting the correct spiral cable is a technical decision with direct consequences for the safety and operational reliability of the vehicle on public roads.
The coiled design of these cables is not an arbitrary aesthetic choice but a functional necessity. During driving, a trailer is in constant motion relative to the tractor unit: when cornering, pulling onto a loading dock or manoeuvring at a distribution centre, the distance between the connection points constantly increases and decreases. A spiral cable for trailers compensates for this movement elastically, returns to its rest position automatically and prevents the cable from dragging along the ground or becoming pinched between vehicle components. This reduces mechanical wear and significantly extends the service life of both the cable and the connector assemblies.
Within the range of spiral cables for the professional transport sector, several subcategories can be distinguished, each with its own technical profile and field of application. The 7-pin spiral cable trailer is the classic lighting cable for drawbar trailers and semi-trailers in heavy road transport. Depending on the application, these are manufactured in accordance with ISO 1185 for power supply circuits or ISO 3731 for signal circuits. On Euro 6 vehicles, vulcanised connectors are used which are watertight and vibration-resistant, eliminating the weakest link in conventional cable assemblies.
The 13-pin spiral cable trailer has become the European standard for trailers with multiple electrical functions. The ISO 11446 standard defines the pin assignment and connection configuration of this interface. In addition to the conventional lighting functions, the 13-pin configuration allows 12V auxiliary power to be supplied to refrigeration units, tail lifts and other electrical systems on the trailer. This makes the 13-pin version the logical choice for new installations requiring more than basic lighting.
For heavy European transport combinations with more complex electrical architectures, the 15-pin spiral cable is the appropriate solution. This conforms to ISO 12098 and integrates the functions of both the lighting circuit and the ABS and EBS signal circuit into a single cable connection. Where two separate 7-pin cables were previously used side by side, the 15-pin version offers a single, streamlined connection that simplifies installation and reduces the risk of loose or incorrectly connected terminals.
The EBS spiral cable is a distinct subcategory specifically targeting the connection of electronic braking systems between tractor and trailer. In accordance with ISO 7638, this cable features the required conductor specifications for the transfer of EBS signals, supply voltage and CAN-bus communication. A correct EBS connection is not only a functional requirement but also a legal obligation for vehicles equipped with an electronic braking system. The 7-pin spiral cable trailer for EBS applications differs from the standard lighting cable in conductor layout, cross-section and connector design and must not be interchanged.
For applications where high current levels need to be transferred — such as charging battery systems on the trailer or powering high-demand electrical equipment — charging current spiral cables are available with heavy-duty conductor cross-sections and compatible power connectors. These coiled cable truck and trailer assemblies use standardised high-power connectors designed to withstand the thermal and mechanical stress associated with repeated connection and disconnection in a workshop or depot environment.
Spiral cables are available both with and without pre-fitted connectors. Ready-assembled cables with vulcanised or plastic connectors are suitable for direct installation without further processing and are widely used for replacement and extension work in truck workshops. Spiral cables without connectors are intended for custom installations where the trailer builder or body builder defines the end connections based on the specific requirements of the vehicle.
For transport operations that fall under ADR regulations for hazardous materials, additional requirements apply to electrical connections. Specifically for these applications, ADR-approved spiral cables are available that meet the stricter requirements for insulation, connection method and fire safety that the ADR standard imposes on vehicles carrying dangerous goods.
Dekoff supplies spiral cables to professional customers in trailer construction, body building and heavy road transport. The range covers all common standards and configurations, from basic lighting cables to complex EBS connections and charging cables for high-power systems. For B2B customers working with fixed specifications or high volumes, the range is structured to ensure the correct cable for every application is available for immediate delivery.