Automotive Wire Harness Protection: The Ultimate Guide

Automobile wiring plays an important role, just like the nervous system of your body. It is responsible for all the signals and electric energy transmission to different parts of the vehicle. Likewise, it needs automotive wire protection from external environmental aspects like heat, water, sunlight, and anything harmful. 

In this article, we will look deeper into the protection types and what you should consider to choose one properly. 

Why Wire Protection Is Important in Automotive Applications

Vehicles have numerous electrical systems, all of which rely on proper wiring. And the more systems the vehicle has, the more protection is required. 

Temperature resistance:

Engines are designed to run continuously at very high temperatures of over 2000°F, to which electrical wires are constantly exposed. A lack of proper wire insulation could damage the wiring, which could potentially cause a short circuit and ignite an electrical fire. The high-temp split loom has been an excellent solution to this overheating issue.

Heavy duty resistance:

Heavy-duty equipment like agricultural machinery runs 24 hours a day. So, we need durable wire harnesses that are made of solid design features. Wiring looms help protect from vibration and heat in several heat resistance ratings. 

Waterproof:

Parts, like the chassis, wheels, front bumper, rear bumper, and the 4-door line, require waterproof treatment before setting it up in the car. Additionally, some other components like lower areas of rear doors, front and back guard areas, ceiling, and engine rooms also get exposed to rain, etc. simultaneously. Now these parts have a significant amount of wiring in them. It includes a front cabin harness, powertrain wiring, rear bumper, 4-door, and battery‘s +ive and -ive wire harnessing. All these harnesses require incorporating the moisture-resistant design. 

Types of Automotive Wire Protection

Different harnesses require specific protection characteristics and properties, such as:

Braided Sleeves

Made of nylon,  a braided cable sleeve offers an open weave. Unlike typical cable protection options made of smooth and unbroken metal or plastic, an open weave has several advantages, such as quicker moisture evaporation, easier heat dissipation, maximum flexibility, and easier inspection in case of suspected damage. Also, braided sleeves provide better durability and dependability. 

Braiding	Advantages	Applications
PVC-coated nylon	Available in a wide variety of colors	When enhancing the look of the harness or tracking wires is necessary
Nomex fiber	Thermal sleeve protection	High-temperature conditions

Braided wire loom drawbacks

1. Firstly, the looming process requires a machine that is quite loud. 
2. Further, the process is quite labor intensive, and laborers need to tape the harness before looming. 

Sleeve protection

Tapes

Tapes can also bundle and protect the wires better. You can use it for various purposes, including protective wrapping, bundling, and sealing, making them versatile and economical. With its many available backings and adhesives, the tape can provide the same level of protection against abrasion, heat, cold, and sound as the other options. Tapes also outperform tube and plastic conduit in terms of flexibility, weight, and ease of installation. 

For selecting a tape

It is important to consider temperature resistance and wire connection.

• A wide selection of low-VOC grades and other adhesive types for soft PVC products
• Aluminum/glass cloth product for heat reflection 
• Polyester, rayon, glass, and cotton cloths with extensive temperature and abrasion performance
• Nonwoven foam and fleece kinds for sound dampening  
• Cloth and PVC for dry-area splice protection
• Self-amalgamating tapes and sealants for water resistance

Spiral tape

Conduits

Also known as convoluted tubing, cable conduits are highly flame retardant and non-heat shrink tubing. This tubing can accommodate various connector back-shells, and you can put several fittings in the tubing to provide a liquid-tight seal or covering. With a wide range of diameters and many colors available, we can widely use them for high protection against abrasion & cuts.

You can find this tubing in different plastics with varied chemical and heat ratings. Some of the plastics include:

Plastic conduit	Advantage	Application
PVC-coated metal	Liquid-tightCorrosion-resistant	Most used in factory wiring and machine connections.
LDPE	Corrosion-resistantChemical-resistantHighly durableFlexible	Good for telecommunication, power utilities, and trenching
Nylon	Protection against impact damage and abrasion	Ideal for vehicle harnesses and hydraulic hoses
Polypropylene (PP)	Highly flexibleCompression strengthhigh-temperature resistance	Mainly used in engine cable assemblies, embedding into walls, and under-floor wiring

For Wiring Harness Configurations

Fishing the wire harnesses through the tubing and other fittings becomes more difficult for complex wiring harnesses.

1. If you do not use fittings at the intersection of the branch, you will need zip ties or electrical tape to secure the convoluted tubing. 
2. Like a braided wiring harness, you must tape the harness before feeding it into the tubing. 
3. Further, you will need to take separate tubing for each branch. As a result, the liquid-tight seal may get affected.

Cable Conduits 

Heat Shrink Tubing

Heat shrink protection is a technique that serves various purposes, such as:

• It offers electrical insulation to an exposed or damaged part of a wire
• It provides protection against moisture, abrasion, dust, and chemicals
• It relieves the strain of cables when held at tension
• You can bundle wires into single units with this tubing
• It allows easy identification of wires due to its availability in a wide range of colors.

Heat shrink tubing is made of special materials with the property of shrinking radially. As a result, the length is shorter on heating. For a proper cable assembly, 

• Finish the wiring;
• After wiring, move the heat shrink tube to the connected wires and cables;
• Expose this tube to any heat source, be it an oven, hot gas, or a heat gun. 
• Due to heat, the tube shrinks around the connection. 

For heat shrink tube application 

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.

Heat shrink protection

How to Select Automotive Wire Protection for Applications

We can make a wise choice, depending on the auto wire harness’s physical properties and electrical performance. 

Sealed or Open System

When choosing cable protection for automotive purposes, the main factor is whether the cables can operate efficiently and reliably, especially within the engine bay.

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 dirt, which make their way to the harness, causing wear and, over time, damage. Hence the need to cover an automotive wire loom 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.

Systems like the IP66 and IP68/69K prevent damage from splashing and high-pressure washdowns, keeping the harness clean and safe from quick wearing off and failure. 

Sealed polyamide 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.

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 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.

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

6 Common Types of Protection for Automotive Wiring Harnesses

Below are six cable wrap options we find in an automotive wiring harness.

Corrugated Flexible Conduit From PE, PA, or PP

PP plastic is a unique material with a high flame redundancy and light-off to prevent sparking a fire.

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

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.

Braided Self-Closed Wrap From PET Monofilament

This wrap has a self-rolling coincidence of around 25% and combines flame redundancy and wear resistance. 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 liquid 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

Automotive wire protection is a must since continuous exposure to extreme environments or working in a heavy-duty condition deteriorates the wiring harnesses with time. Also, you need a properly calibrated and reliable system to prevent electromagnetic interference on circuits and eradicate short courses. 
Thankfully, a wide selection of protection is available, so you can choose one that better serves your needs. Wiringo 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.