Custom Cable Design Guide | Cable System Best Practices

Proper cable design is essential across industries like telecommunications and power distribution, ensuring the reliability, efficiency, and safety of electrical systems. A well-designed cable minimizes risks such as signal interference, power loss, and mechanical failure—critical factors in maintaining optimal performance and extending system longevity. Now, let’s explore how to create an effective cable, starting with its core components.

Key Components for Cable Configuration

Normally, a cable may include the conductor, insulation, shielding, wraps, fillers, strength members,  breather tube, and jacket.

Conductors

Conductors are the core of a cable, carrying electrical currents and significantly affecting the cable's overall performance. The conductor can be made as solid or stranded. Solid conductors offer better signal transmission over long distances with minimal loss, making them suitable for fixed installations. Stranded conductors are made of several thin strands twisted together, providing flexibility and resistance to fatigue, which is ideal for applications requiring movement or bending.

Also, the arrangement of strands within a stranded conductor affects the overall cable flexibility and strength. Different stranding techniques can be used depending on performance needs:

• Concentric stranding: Wires are precisely layered in concentric circles, offering a round profile and consistent electrical performance.

• Bunched stranding: Strands are twisted together randomly, maximizing flexibility but with less uniformity.

• Rope lay stranding: Bundles of bunched or concentric strands are twisted into a larger rope-like structure, providing excellent flexibility and durability for heavy-duty use.

• Unilay stranding: All layers are twisted in the same direction with the same lay length, giving a smoother finish and compact shape.

• Equilay stranding: Similar to unilay, but with alternating layer directions to balance stress and improve stability.

• Unidirectional stranding: All layers twist in one direction, with increasing lay lengths to combine flexibility and strength.

Choosing the right stranding technique depends on your application’s specific demands. For high flexibility, common in robotics or portable devices, bunched or rope lay stranding is ideal. If precise dimensions and a smooth outer profile are essential, such as in aerospace or medical equipment, opt for unilay or concentric stranding. In environments with significant mechanical stress, equilay or unidirectional stranding provides superior structural stability.

Insulation

Cable insulation plays a vital role in both protecting and ensuring the efficiency of electrical and communication systems. It serves as a non-conductive barrier that keeps the electrical current flowing through the conductors and prevents unintended contact between them, reducing the risk of short circuits. Insulation also enhances signal quality by minimizing interference such as electromagnetic noise and crosstalk between adjacent cables. Moreover, it acts as a protective shield against environmental factors like moisture, chemicals, heat, and physical damage, which can all degrade cable performance.

Shielding

Cable shielding is a crucial technique used to protect wires and cables from electromagnetic interference (EMI) and radio frequency interference (RFI), ensuring the integrity of signal transmission. Shielding acts like a barrier that both blocks external noise from entering the cable and prevents internal signals from radiating out, which is important for avoiding disruptions in nearby devices. This protection is especially important in environments where sensitive electronic equipment operates, such as telecommunications or audio systems.

There are 3 common types of shielding:

• Braid Shielding: Composed of woven strands of copper or aluminum, braid shielding offers robust structural integrity and moderate protection against EMI, especially in environments with low-frequency noise. Due to its flexibility and higher flex life, it is suitable for cables requiring frequent movement. Braid shielding also reduces crosstalk but can be slower to manufacture and harder to terminate with higher costs.
• Foil Shielding: Made from a thin layer of aluminum or copper bonded to a polyester film, foil shielding offers 100% coverage, making it highly effective against high-frequency EMI and crosstalk. It's lightweight, cost-effective, and easy to apply. However, foil shielding is less flexible, making it ideal for stationary applications with limited movement, where long-term durability is not compromised by flexing.
• Spiral Shielding: Often found in audio cables, this type involves wrapping wire in a spiral pattern around the conductors. While it provides less EMI protection compared to braid or foil, it offers superior flexibility, making it ideal for applications like audio cables where frequent flexing is necessary, even though its overall flex life may be shorter than that of a braid.

Wraps

Wraps, also known as tapes, enhance noise suppression between components inside components, reduce crosstalk, and facilitate the assembly process. These wraps are applied around conductors, fillers, or the entire cable core to maintain structure and provide an additional layer of protection.

Fillers

Fillers are used in cables to maintain structural integrity, improve durability, and reduce friction between conductors. They fill gaps within the cable to add tensile strength and protect against external elements.

Jacket

Jackets serve as the outermost layer, offering essential protection against environmental factors, mechanical damage, and chemical exposure. Its main role is to safeguard the internal components.

The jacket shields the cable from moisture, UV rays, chemicals, and extreme temperatures, making it especially important in harsh environments like industrial sites or outdoor installations. It also provides mechanical protection from physical damage caused by abrasion, impact, or bending, and must resist chemical exposure in environments where oils, solvents, or acids are present.

How to Design a Cable: What Else to Consider

Designing a cable involves more than just choosing the right components; it requires a detailed understanding of how each element interacts with the environment, electrical requirements, and mechanical stresses. Let’s dive deeper!

Material Selection for Components

The choice of material and design is crucial in cable construction, as it directly influences conductivity, flexibility, and long-term durability. Each component in a cable—whether it’s the conductor, insulation, or outer jacket—must be selected with the end-use environment and performance demands in mind. Here are the most common materials used across different cable layers:

Conductor Materials

• Copper: The industry standard for its excellent electrical and thermal conductivity, corrosion resistance, and workability. Tinned copper adds oxidation protection in moist or outdoor environments.

• Aluminum: Lightweight and cost-effective, aluminum is widely used in long-distance power transmission, although it has lower conductivity and flex life than copper.

• Steel: Used where mechanical strength is needed. Often found in copper-clad forms to improve conductivity while retaining durability, especially in coaxial cables and grounding systems.

• High-strength metal alloys (e.g., tin-copper, cadmium-copper): Designed for specialized applications requiring enhanced tensile strength and fatigue resistance.

• Tinsel wire: Constructed by wrapping metal foil around a textile core, tinsel wire is ideal for high-flex, low-current applications, such as headsets and phone cords.

Insulation Materials

Selecting insulation depends on flexibility, temperature tolerance, and resistance to moisture, abrasion, and chemicals:

• PVC: Cost-effective with moisture and chemical resistance, good for general wiring.

• PE, Foam PE, and XLPE: Offer excellent dielectric strength and moisture resistance; XLPE adds heat tolerance.

• PP: Durable with higher temperature limits, common in telecom and data cables.

• Fluoropolymers (PTFE, FEP, PFA, THV, PVDF, ETFE): Withstand high heat and chemicals, ideal for aerospace and industrial use.
  Silicone: Extremely flexible and heat-resistant, perfect for dynamic or medical environments.

• TPE family (TPO, TPV, TPES, TPE-E): Known for elasticity, weather resistance, and toughness in mobile applications.

• Nylon: Used as a secondary insulation layer to reinforce strength and abrasion resistance.

• TPU (PUR): Excels in abrasion resistance and flexibility, commonly used in retractable cords and robotics.

Filler Materials

Fillers support the cable structure and prevent conductor movement. They are crucial for maintaining shape and enhancing flexibility:

• Foam: Lightweight and compressible, foam fillers are often used to reduce gaps between conductors.

• Polyethylene (PE): Common in long cables for structural support and low interference. Its moldability and light weight make it ideal where form and flexibility are both important.

Strength Members

These materials reinforce the cable to resist pulling forces and mechanical stress:

• Aramid fibers (e.g., Kevlar): High tensile strength and lightweight, ideal for flexible and high-pull-strength cables.

• Steel: Offers both tensile and compressive strength for heavy-duty use.

• Fiberglass rods: Provide rigidity and compressive strength, though less flexible and more brittle in cold environments.

Breather Tubes

Used for venting or fluid flow, breather tubes must match the environmental and functional requirements of the cable. It depends on whether the tube is venting heat, carrying gases (like air or oxygen), or transporting fluids (like chemicals or water).

• Polyethylene (PE): Lightweight, semi-rigid, and chemical-resistant; widely used in multi-conductor cables.

• TPE (Thermoplastic Elastomer): Highly flexible and durable, ideal for cables requiring movement.

• PVC: Cost-effective and chemically resistant, suitable for general environments.

• Polyurethane (PUR): Tough and abrasion-resistant, used in rugged conditions.

• PTFE: Excellent heat and chemical resistance, ideal for harsh industrial settings.

• Nylon: Strong and wear-resistant, good for high-durability needs.

• Aluminum: Used in non-cable applications like insulating glass to manage pressure.

• Synflex Nylon: Durable tubing used in air brake systems with neoprene connectors.

Wrap Materials

Wraps protect the inner layers and control electrical performance:

• PTFE tape: Used in high-speed data cables for its low signal loss and durability at high temperatures.

• Polyimide, AL/MY, or Mylar: Provide heat and abrasion resistance, often used in industrial settings.

• Paper tape: An economical choice used mainly for ease of cable jacket removal. Not suitable for high heat or movement.

Jacket Materials

The outer jacket shields the entire assembly from mechanical and environmental damage. Options include:

• PVC: Versatile and flame-retardant, suitable for everyday wiring.

• TPE (TPO, TPV, TPES, TPE-E): Offers tailored environmental resistance and flexibility.

• Silicone: Withstands extreme temperatures, ideal for medical and industrial settings.

• Fluoropolymers: Chemical-resistant and durable, made for rugged use.

• EPDM: Withstands UV, ozone, and weather, great for outdoor installations.

• TPU (PUR): Combines oil resistance, elasticity, and toughness for cables that move frequently.

Clarify the Intended Use

Understanding the environment where the cable will be used is crucial. Factors like temperature extremes, humidity, chemical exposure, and physical stress such as bending and vibration significantly impact the cable design.

Termination Methods

Termination is a critical aspect of cable design, as it ensures secure connections and affects the overall durability of the cable assembly. There are 3 primary termination methods:

• Crimping: Provides reliable connections with stranded conductors using automated machinery and special tooling. It’s efficient for mass production but requires precise tooling for consistency.
• Soldering: Suitable for both solid and stranded conductors, offering a wider range of sizes. It requires skill to ensure strong, reliable joints, making it ideal for custom or small-scale applications.
• Molding:  Involves forming a protective outer layer, typically with plastic or rubber, around the cable termination. Molding adds environmental protection and robust durability, with overmolding offering extra waterproofing and mechanical reinforcement.

Equally important is strain relief, which protects the cable entry point at the connector from mechanical stress and premature breakage. Overmolds and heat-shrink tubing can provide basic strain relief at the cable-to-connector junction, but overmolding alone should not be the sole solution. For more reliable support, consider built-in connector components such as two-piece cable clamps or collets, the latter offering superior performance in most cases.
If the application also requires bend relief to reduce stress from cable flexing at the connector exit, heat-shrink tubing or pre-molded bend reliefs supplied by the connector manufacturer are effective choices. For a fully integrated and polished solution, a custom overmold can provide both strain and bend relief while enhancing the visual finish of the entire cable assembly.

Voltage Regulation

Voltage regulation refers to the cable's ability to maintain a stable voltage level between the source and the load, despite variations in current flow. Poor voltage regulation can result in excessive voltage drops, leading to equipment malfunction or damage, especially in long cable runs. The  

When designing cables, it's crucial to consider international standards to ensure safety and performance. ISO standards like ISO 9001 (quality management) and ISO 13485 (medical devices standards) are globally recognized.

In North America, UL (Underwriters Laboratories) and CSA (Canadian Standards Association) govern safety, flame resistance, insulation, and voltage ratings. UL standards like UL 1581/UL 758 cover flexible cords and electrical wiring, while CSA sets similar benchmarks for Canada. Adhering to these standards ensures compliance, safety, and product reliability across various applications.

Read More: Order Custom Cables Procedure

Common Mistakes to Avoid When Designing a Cable

Designing a cable might seem straightforward, but small missteps in the process can lead to costly errors, compromised performance, and product failures in the field. Let’s see some of the most common mistakes when designing a cable.

Over-Specifying Specifications

Specifying cables with overly precise tolerances or unnecessary components can increase manufacturing complexity and cost. When tolerances are too tight, it can slow down production, increase labor costs, and make the design more difficult to assemble. It's essential to balance precision with practicality, ensuring the design meets the requirements without being overly complex or expensive. 

Vague Design Descriptions

On the contrary, providing vague or imprecise design specifications can also lead to unwanted results, like misinterpretation and errors during the manufacturing process. Clear, detailed descriptions, including specifics like voltage, temperature, flexibility, and gauge, are necessary to ensure that the final product meets the desired performance and quality standards.

Assembly Difficulty

Designs that are difficult to assemble can lead to delays, increased labor costs, and a higher risk of errors during production. For example, selecting wire and terminal pairings without considering insulation size can result in incompatibilities, even if they appear compatible on paper. Ensuring that components fit together properly and can be assembled efficiently is crucial for a successful cable design.

Disregarding Connector Compatibility

Choosing connectors that do not align with the cable's design or application can lead to connectivity problems and signal degradation. Connectors must match the cable's physical dimensions and electrical specifications while considering environmental resistance. Mating cycles, ease of connection, and mechanical robustness are important factors to consider when selecting connectors.

Contact Winfox for Expert Custom Cable Design Solutions Now!

Cable design plays a pivotal role in ensuring the reliability, safety, and efficiency of electrical systems. It involves careful consideration of various components like conductors, insulation, shielding, and jackets, each contributing to the cable's overall performance and longevity. Proper design helps mitigate issues such as electromagnetic interference, mechanical stress, and environmental hazards, thereby extending the operational life of the system.

For custom cable solutions that truly fit your needs, Winfox is your go-to partner. With decades of experience and a robust portfolio of patents, we offer a wide range of high-quality custom cable assemblies, including medical cables, automation cables, flat ribbon cables, coil cords, and other types of cables. Our expert team excels in tackling complex challenges to ensure your cable system delivers optimal performance and durability. Discover how Winfox can bring your custom cable design projects to life with precision and expertise. Contact us today for exceptional service and innovative solutions.