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HomeTips & GuidesWaterproof Wiring Harness: Why A Waterproof Wire Harness Design Matters

Waterproof Wiring Harness: Why A Waterproof Wire Harness Design Matters

Waterproof wiring harness in autos play a significant role in protecting the car’s electrical components. 

A moisture-resistance design plays a significant role because encountering water is inevitable. 

Often, the car will wade through water. Also, the water can contact the electrical components when driving in the rain. It can lead to electrical shorts and fires. 

In this guide, we’ll explain the benefits of waterproof wiring harnesses. We’ll also cover your considerations when insulating your current carrying wires. 

Table of Contents

Things to Consider When Making a Waterproof Design

Here are the primary concerns in creating a waterproof car design: 

Wading Depth of a Vehicle

Wire harnesses. 

Wire harnesses. 

All auto motors feature a wading depth level. It typically indicates the depth level the car can wade through water without harming the electrical systems. 

Also important, there’s a wading line running horizontally in all vehicles. It shows the wading depth level throughout the car’s length. 

Auto engineers ensure all the car’s electrical components are above the wading line. Nonetheless, installing some electrical parts below this line may still be necessary. 

In such a case, waterproof material protects the element from probable exposure. 

Dry and Wet Area and Waterproof Harness Area

Making car harnesses. 

Making car harnesses

Some car parts are considered wet areas and thus require additional shielding to the harnesses.

Often car manufacturers apply electrical connectors to shield these parts from water exposure. The wet areas include the following: 

  • Front bumper
  • Rear Door Lower Areas
  • Engine rooms
  • Ceiling
  • Rear bumper
  • Chassis
  • Guard Areas
  • 4-door line
  • Wheels

Protecting these parts requires an extensive waterproofing material.

But, it would be in vain to apply connectors and leave the check-in points exposed. Hence, manufacturers use heat-shrink tubing to protect these parts. 

The Waterproof Design of the Wire Harness

Applying waterproof harnesses to cables. 

Applying waterproof harnesses to cables. 

When crafting a waterproof design for a car’s wire harness, there are several considerations you need to make. 

Harness Winding Method

You can pick from one of the four winding techniques, depending on the outcome you would like to realize. 

  • Semi-Encapsulated Winding Method- The spacing width is half the tape’s width. 
  • Double winding method
  • Rough winding method
  • 2/3 packaging winding method

Most importantly, some parts require extra waterproofing as they are in direct contact with elements of nature. These include the following: 

  • Powertrain wiring harness 
  • Front cabin wiring harness
  • Door wiring harness

In these parts, the ideal winding method is the semi-encapsulated method. 

Selection of Waterproof Connectors

Insulation on connectors. 

Insulation on connectors. 

Whole vehicle connectors are crucial in enabling the docking of electrical components. It significantly aids in the following: 

  • Facilitating excellent insulation
  • Limiting the chances of short circuits 
  • Ensuring reliability in signal transmission

We use connectors and positioning clips to ensure they remain in position throughout. Also, ensuring all the connectors in a car’s most exposed parts are waterproof is essential. 

For instance, those in the engine compartment need waterproof rubber sealing plugs to prevent water contact. Lastly, when selecting automotive connectors, it’s essential to consider their temperature resistance characteristics.


Visible wiring harness connected by a plug.

Visible wiring harness connected by a plug.

Wiring harness inline points require exquisite sealing as these are points where water can enter the joints. It also applies to vis protection and grounding points. Why? 

When the electrical module is in operation, there’s an increase in the internal temperature. Nonetheless, this decreases upon the module switching off, resulting in a reduction of the internal pressure. 

The resulting pressure difference makes it easy for water to flow inside, especially if there’s an improper seal.

Thus, in addition to using excellent waterproof connectors, proper sealing can prevent water entry into these parts. 

Also important, it is imperative to include a rubber protective cover in scenarios where the cables pass via a body sheet metal hole. 

Wire Harness Arrangement Protection

Lastly, you can combine a waterproof material with a design that allows water to trickle down naturally to prevent accumulation. There are many ways to realize this, but a well-set three-dimensional layout works perfectly. 

Start by dealing with the vehicle grounding, the leading cause of water entry into the car’s electricals. Ideally, you should have the vehicle’s electrical installation point relatively higher than the grounding point. 

Automotive Wiring Harness Waterproof Rating

IP Ratings. 

IP Ratings. 

The IEC (INTERNATIONAL ELECTROTECHNICAL COMMISSION) is a body that provides classifications of electrical appliances. It is based on the electrical parts’ moisture and dust resistance. 

These ratings are presented as IP (INGRESS PROTECTION) protection level system values, usually in IPXX format. 

The ‘XX’ in the rating are usually numbers; the first represents the resistance to dust.

 On the other hand, the second one represents the waterproof rating of the appliance. 

The dust ratings range from zero to six. Thus, an IP0X rating means the wiring harness offers zero protection from dust. 

Conversely, an IP6X rating means the wire harness should provide maximum protection from dust entry. 

On the other hand, the waterproof test ranges between 1 and 8. IPX1 is the lowest rating and only protects the dripping water from entering. 

The highest is IPX8, meaning the harness is foolproof from any water entry. 

An IPX8-rated wiring harness will even safeguard the electrical elements in the event of the auto vehicle sinking. 


Keeping electrical connections in a car safe from water is critical, as contact effects can be devastating. Therefore, a waterproof wiring harness is essential. 

There are several factors to consider when setting this up, including the car’s wading depth and taking special care of the wet areas. 

Hi I am Christa, sales manager of Cloom.

I have extensive expertise and experience in wiring harnesses and I believe I can help you.

And we have a very professional technical team who can clearly understand the customer’s needs and give professional suggestions and solutions after receiving the drawings.

If you also have wiring harness needs, please send me the drawing so that we can give you our quote and start our business.

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