Automotive Wire Harness Protection: The Ultimate Guide

Vehicles have numerous systems, all of which rely on proper wiring. The wiring regulates power, receives signals from the ECU to control components, and stores data that ensures the car runs smoothly. And the more systems the vehicle has, the more wiring is required. 

Engines are designed to run continuously at very high temperatures of over 2000F, to which the wires are constantly exposed. A lack of proper wire insulation would damage the wiring, which could potentially cause a short circuit igniting an electrical fire. However, overheating is just the beginning of automotive wire harnesses’ problems. The wiring needs noise reduction, thermal protection, electromagnetic shielding, radiant heat protection, abrasion, and mechanical protection. All in all, automotive wire harness protection is necessary.

What Are Wire Harness Protections/Coverings? 

Harness protection is the sleeve, wrapping, conduit, tape, or tubing that securely covers and bundles the harness, protecting it from high temperatures and environmental conditions. However, different harnesses require specific characteristics and properties, such as:

Braided Cable Sleeve

Braided cable sleeves are made of mesh to protect your wires. You can singe the sleeve with a hot knife to prevent unraveling at the edges.

You could opt for expandable sleeves made of polyester that provide an open-end weave construction, allowing for easy installation and reducing installation costs. It protects the wires by allowing moisture and heat to dissipate. Plus, it maintains flexibility even if you bundle a couple of wires together. Expandable also comes in polyphlyne that best suits high-temperature assemblies. Also, polyline has low moisture stability, low wear, and high chemical resistance. 

You can also opt for self-closing braided sleeves that are abrasion resistant and made of polyester. These provide a 25% overturn, hence easy access to the bundle inside. Plus, it can be assembled over already laid wires.

Another sleeve option is the thermal sleeve protection made of Nomex fiber. The fiber is ideal for high-temperature conditions and provides abrasion resistance and thermal protection.

Cable sleeve

Cable sleeve

Cable Wrap

Spiral cable wraps provide cost-effective protection for wires and hoses. They’re flexible, crush resistant, and easy to install. These cables can be branched to provide a simple cable management solution.

Most wraps are made from polyethylene or nylon. Nylon wraps are more heat-resistant because they contain stabilizers that slow down the loss of physical properties as temperatures increase. 

Polythene wraps, on the other hand, provide a more durable cable wrap solution. Plus, polythene wraps maintain their integrity and strength even after being flexed and bent a couple of times.

You could choose between nylon and polythene with hook and loop braided cable wrap. They offer the simplest cable assembly management solution. These cables better serve nonindustrial purposes such as lighting and photography. Also, they can be reused, which could save you a lot. Similarly to spiral wraps, breakouts could happen.

The Cable wrap

Cable Conduit

Cable conduits route and protect wires in machines and structures. The lines have grounding and bonding abilities, helping minimize electromagnetic interference. Pipes also prevent emissions from the power cables they house.

Some conduits are plastic, offering more flexibility and higher fatigue life. Plastic pipes are vital, enabling them to recover quickly after being crushed. They also provide UV resistance, allowing for use in exterior areas. Some of the plastics include:

  • HDPE – Durable, flexible, and chemical resistant. Ideal for telecommunication, power utilities, and trenching.
  • Polypropylene – Offers high flexibility and compression strength. Mainly used in cable assemblies, embedding into walls, and under-floor wiring.
  • Nylon – Protects against abrasion and impact damage. Ideal for vehicle harness protection and hydraulic hose protection
  • PVC coated metal – It’s corrosion resistant and liquid tight. Most used in factory wiring and machine connections.
Conduit image

Caption: Conduit image

Heat Shrink Tubing

Heat shrink tubing involves enclosing cables and wires in plastic tubes. To provide a close tight fitting for the wires and a rope,e you’ll need to shrink the lines using a heat gun or blow torch.

Polyolefin is mainly used to make heat shrinking tubing because of the following reasons:

  • Flexibility
  • Durability
  • Chemical resistance
  • UV resistance
  • Ideal electrical properties

The tubes not only act as cable sleeves but also provide strain relief. Cables and wires often serve a shorter lifespan because of the strain caused by working in limited spaces or being fast. Heat shrinking tuning reduces the stress on your wires and cables enabling them to work effectively. 

With heat-shrinking tubing, you can opt for colors or clear tubing. Colored tubing is ideally used in automotive, cable TV, wireless and telecoms, and electronics, while clear tubing is used primarily for electronics, automotive, and appliances. You could opt for the clear tubing, especially when heat retardancy is a priority, but mechanical performance and electrical insulation are vital.

Heat shrink tubing

Heat shrink tubing

Tape

Taping is a tiresome task. Although tape might not be the best solution due to its high cost, it takes up little space and is easy to install. The tape is wound around the wires in a spiral form to cover the areas between sleeves and other solutions.

Taping

Taping

How to Select Cable Protection for Automotive Applications

When choosing protection for your automotive’s wire harness, there are several factors to consider, including:  

 Sealed or Open System

When choosing cable protection for automotive purposes, the main factor is whether the cables can operate efficiently and reliably with zero to minimal protection.

Automotive split walls are highly flexible and light. Therefore, they tend to peel open when exposed to frequent vibration or excess flexing. 

When that happens, it lets in water and debris, which make their way to the harness, causing wear and, over time, damage. Hence the need to cover automotive looms with tape to seal off the conduit and help avoid such problems. 

However, taping the automotive looms demands extra work. A lot of labor goes into the building process, consequently increasing the overall costs and reducing the functionality of the harness. And since automotive looms are made of lightweight materials, they don’t offer adequate protection on expensive vehicle harnesses.

Cable protection systems like the IP66 and IP68/69K protect the cable from splashing and high-pressure washdowns, keeping the harness clean and safe from quick wearing off and failure. 

Sealed polyamide protection systems are more robust and serve longer than taped automotive looms. Polyamide also offers a wide selection of materials with numerous features and different flammability ratings, allowing you to make the best choice according to the intended use.

Automotive Wire Harness Protection: Location of Harness

When the harness is close to the transmission, engine, or catalytic converter, it requires high-temperature polyamide protection. 

There’s a wide variety of products with temperature ratings ranging between -400C to 1150C and products that can handle temperatures of up to 3000C. 

You don’t have to use solid materials if the harness is inside the vehicle. However, a retrofittable and divisible conduit system could prove beneficial, enhancing the ease of adding wires for add-on features like lighting and WiFi.

Material Selection

Light and medium wall products are sufficient if the components are not exposed to harsh conditions or rough handling. But if they will be exposed to extreme conditions, it’s better to go with the heavy wall polyamide cable protection made of material with the following qualities:

  • High impact and can resist high temperatures
  • Increased flexibility to continuous motion, such as in the robotics field
  • Low toxicity performance in passenger areas that complies with the Bombardier and ASTM standards
  • UL94 V-0 compliance for low smoke

Robust polyamide cable protection systems also offer increased flexibility and high impact resistance, vital in applications involving jumper cables linking automation, such as subway cars. 

The protection system should also have an increased diameter to protect large bundles of cables. In addition, the capability to be retrofitted and divided to allow adding or removing of wires during the vehicle’s service life or while building the prototype.

Automotive Wire Harness Protection: Cable Protection System Accessories

The best cable protection system supports the conduit, ensuring efficient and effective installation. There are several accessories to enhance performance, including:

  • Y and T junction fittings
  • Divisible lock nuts
  • Fittings with inbuilt strain relief
  • End sleeves
  • Clamps
  • Abrasion rings
  • Divisible fittings for retrofit applications
Image of Clamps

Image of Clamps

For heat shrink tubes

  1. Whether to opt for a single wall or dual wall heat shrink. Although the single fence is widely used, the double wall (adhesive lined tubing) has a better connection and more robust seal, among other advantages. The following are factors to consider when choosing heat shrink tubes: 
  2. The tube’s shrink ratio. The heat shrink ratio differs from the initial heat shrink tube size to its skeletal form. The difference is a ratio of 2:1 to 4:1. Typically, the heat shrink tube decreases the size by 50% to 75% once some heat is introduced.
  3. Lastly, it’s essential to consider the heat-shrinking tube size.

6 Types of Cable Wrap for Automotive Wiring Harnesses

Below are six cable wrap options, depending on the auto wire harness’s physical properties and electrical performance.

Automotive Wire Harness Protection: Corrugated Flexible Conduit From PE, PA, or PP

While the car is running, the engine gets exposed to high temperatures. Therefore, the PP plastic wrap for the engine is a unique material with a high flame redundancy and light-off to prevent sparking a fire.

PP wrap has a high melting point, making it the perfect wrapping material. Even when the engine is under extreme temperatures, it’s less likely to result in a fire. 

In addition, PP corrugated tubes have a low thermal conductivity. Therefore, even if the engine temperatures are high, it won’t affect the expected operations of the neighboring components.

Self-Closing Non-expandable Sleeving From Polyester Monofilament and Multifilament

This open-type design is easier to install and remove. Also, it has high wear resistance, providing excellent protection for the harness during bending activity.

Automotive Wire Harness Protection: Braided Self-Closed Wrap From PET Monofilament

This wrap has a self-rolling coincidence of around 25% and combines flame redundancy and wear resistance to provide protection. It also has a high-temperature component peripheral guard.

Dual Wall Adhesive Heat Shrink Tubing From Polyethylene

This tubing comprises an outer polythene layer and an inner layer of hot melt adhesive. It fits closely on wires, smoothing rough edges and providing electrical and thermal insulation. 

The adhesive tubing ensures a tight seal against moisture and chemicals that could corrode the harness. However, it’s challenging to apply and requires a heat gun, which increases production time.

Cable Expandable Sleeving From Polyester Monofilament

This sleeving is often used to cover wire harness tubes, industrial hoses, and cables. It can maintain complete flexibility in any direction, regardless of low temperatures. Also, it allows for repeated flexing of cable assemblies and wire bundles without causing damage.

Fiberglass Braided Sleeve

The fiberglass braided sleeve has a temperature classification of about 2000C and self-extinguishing capabilities. In addition, it has a high voltage resistance and a wide temperature range. It’s widely used in motor peripherals and generators.

Conclusion

Harnesses must ensure smooth transmission of signals and connection of circuits. You need a properly calibrated and reliable system to prevent electromagnetic interference on circuits and eradicate short courses. Thankfully, a wide selection of components is available, so you can choose one that better serves your needs.

Cloom Tech provides all wire covering and cable protection services, from heat shrink wrapping to expandable tubing. Our team of experts is always ready and equipped to handle all your requirements in all applications.

Hey, I am John, General manager of Cloom and OurPCB.

I am a responsible, intelligent and experienced business professional with an extensive background in the electronics industry.

Reach me at [email protected] to get a quote for your projects.

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