Everything to know about wiring harness engineering


5 mins

Everything to know about wiring harness engineering

Designing an electrical wiring harness is probably one of the most important steps that makes it possible for any electrical device to function. In point of fact, the overall design of the harness is directly proportional to the durability and efficiency of the machine the harness is installed in. It is equally important to look into the application of the harness along with the functionality, this is where engineering comes to play. 

What is a wiring harness?

A wiring harness is a collection of wires, cables, and connectors that are bundled together in a specific arrangement to transmit electrical power and signals between different components and systems in a vehicle, machine, or other equipment. The harness acts as a central nervous system for the equipment, ensuring that all electrical connections are properly organized, protected, and functioning correctly.

Wiring harnesses can range in size and complexity depending on the equipment they are used in. They are commonly used in automobiles, aircraft, construction equipment, and industrial machinery, among other applications. Wiring harnesses can be made from a variety of materials, including copper, aluminum, and synthetic fibers, and can be designed to withstand harsh environmental conditions such as heat, vibration, and moisture.

In addition to providing a neat and organized way to manage electrical connections, wiring harnesses also simplify the installation and maintenance of electrical systems, and can reduce the risk of electrical faults or fires caused by improperly connected wires. 

Wiring harness design

Wiring harness design is the process of creating a plan and layout for a collection of wires, cables, and connectors that will be bundled together to transmit electrical power and signals between different components and systems in a vehicle, machine, or other equipment. The design of a wiring harness involves considering several factors, such as the electrical requirements of the equipment, the physical space available for the harness, the operating environment, and the manufacturing and assembly processes.

Wiring harness design is a critical part of the engineering process, as it plays a key role in ensuring that electrical systems are organized, reliable, and efficient. The successful operation of any given machine or component is dependent on its connection to the wire, the overall flow of current and on how well the harness is routed. 

Importance of wiring harness 

When it comes to protecting your electronics, a wiring harness is absolutely necessary. They are primarily used for the following:

  • Reliability: Wire harnesses provide a reliable way to transmit electrical power and signals between different components and systems in a vehicle, machine, or other equipment. A well-designed harness ensures that all connections are properly organized, protected, and functioning correctly, reducing the risk of electrical faults or failures.

  • Safety: Proper wire harness design can reduce the risk of electrical fires caused by improperly connected wires or other electrical faults. By bundling and protecting wires, harnesses prevent accidental contact with other components and reduce the likelihood of short circuits and other hazards.

  • Efficiency: Wiring harnesses can improve the efficiency of electrical systems by reducing the amount of time and effort required for installation and maintenance. By providing a centralized, organized way to manage electrical connections, harnesses simplify the assembly and repair process, saving time and reducing costs.

  • Customization: Wire harnesses can be designed to meet the specific needs of a particular application or piece of equipment. By customizing the layout, routing, and components of the harness, engineers can optimize the performance and reliability of the electrical system.

Uses of wire harness assemblies 

Wire harness assemblies can be used for a variety of things. The agricultural, automotive, communication, manufacturing, and medical industries, to name just a few, are all included in the list of applications. 


The weight of a wire harness assembly in the aviation industry can vary depending on the specific application and requirements. Factors such as the length of the wires, the number of connectors, and the materials used can all impact the weight of the harness. However, wire harness assemblies are designed to be as lightweight as possible while still meeting the necessary electrical and mechanical requirements. Harnesses’ weight should not exceed the allowable weight of the harness. 

Military & defense

Wire harness assemblies play an important role in military and defense applications, where reliability and durability are critical. Military and defense equipment, such as tanks, planes, and communication systems, require complex electrical systems that must operate in harsh environments, including extreme temperatures, high vibration, and exposure to moisture and dust. Wire harness assemblies can be designed and manufactured to withstand these conditions, ensuring that the electrical connections remain reliable and secure even in the most challenging environments.


In space, equipment must operate in extreme conditions, including exposure to high levels of radiation, extreme temperatures, and vacuum environments. So, the harnesses used are costly as very high-end protection materials are used and it needs to weight within the limitations set. The compact and lightweight design of wire harness assemblies also makes them ideal for space applications where weight and space are at a premium. 

Wire harness assemblies are used in a variety of space applications, including satellites, space probes, and the International Space Station, providing a vital interface between different components and systems. 


Without the incorporation of wire harness assemblies into the devices utilized in hospitals and doctor's offices to treat modern ailments, it is conceivable that modern medical care would not be possible. Medical instruments must rely on the durability and adaptability of wire harness assemblies to maintain functionality because they are frequently used.

Automotive sector

Wire harness assemblies are installed in automobiles to assist in the distribution of electric signals and electricity throughout the vehicle. Starting the ignition, turning on the lights, cooling and heating the vehicle, listening to the radio, and opening the windows all depend on the electric power and signals that travel through the wire harness.

Agricultural industries

Wire harness assemblies are utilized in a significant amount of the agricultural sector's current vehicles and equipment. Heavy machinery like tractors and cultivators can run year-round thanks to the organization and safety features of wire harness assemblies.

Communications systems

The world is connected by wire harness assemblies in global communication systems. The infrastructure that enables instantaneous communication relies on wire harness assemblies to power everything from modems to routers, broadband networks to satellite receivers.

Industrial & manufacturing

Wire harness assemblies are frequently utilized in manufacturing and industrial control processes. Wire harness assemblies organize these intricate connections of cables and wires to streamline the production process and guarantee the optimization of the much larger manufacturing components for fueling automation. 

Wire harness assemblies are a feature that can be found in electrical systems all over the world. It is possible that modern technology would not be nearly as effective without them.

Basic process of wiring harness design 

The fundamental steps for designing a wiring harness using the aforementioned elements are outlined in the following steps.

Requirements gathering

The design process starts by gathering the requirements of the wiring harness, including the electrical and mechanical specifications, the target application, and any relevant industry standards. 

Study & analyze data pack

Once the requirements are known, the next step is to analyze the data pack, and select the appropriate components, such as wires, connectors, terminals, and other components necessary to build the harness.

Schematic design

The schematic design involves creating a graphical representation of the wiring harness, including the wiring diagram, bill of materials, and any other relevant documentation. The design should take into account the physical space available for the harness, as well as any constraints imposed by the operating environment.

3D routing & material selection (BOM)

3D routing and material selection impact the overall functionality and reliability of the harness. 3D routing involves creating a digital model of the wiring harness that takes into account the physical layout and routing of the wires, connectors, and other components. The Bill of Materials (BOM) lists all the components required to build the wiring harness, including the specific materials and quantities needed for each component.

Flattening & manufacturing documents

Flattening involves carefully mapping out the routing of the wires and connectors, taking into account any bends, twists, or other features that might impact the final shape of the harness. Once the harness has been flattened, manufacturing documents such as from/to table, splice table, connector lists, etc., are created that specify the exact components and materials needed to build the harness. 

This includes detailed instructions on the routing of the wires and connectors, as well as any other relevant information, such as torque specifications or heat shrink requirements.

Prototyping and testing

Once the design is complete, the harness is typically prototyped and tested to ensure that it meets the requirements of the target application and any relevant industry standards.

Production and quality control

Finally, the harness is produced, and a quality control process is implemented to ensure that each harness is manufactured to the same high standards and meets the necessary performance and reliability requirements.

Common errors to avoid in wiring harness design

Wiring harness design is a complex process that requires careful attention to detail to ensure that the harness performs reliably over its lifetime. Here are some common errors to avoid in wiring harness design:

Improper wire selection

Using the wrong type of wire or gauge can lead to issues such as voltage drop, overheating, and insulation breakdown. It's important to carefully consider the electrical requirements and environmental factors of the application when selecting wire.

Inadequate strain relief

Strain relief is important to prevent wire breakage and failure due to mechanical stress. Insufficient or improperly designed strain relief can lead to wire fatigue and failure over time.

Improper bundling

Poorly bundled wires can result in electromagnetic interference (EMI), cross-talk, and increased wire stress. Careful attention should be paid to the bundling process to ensure that wires are organized and routed properly.

Inaccurate labeling

Proper labeling of wires, connectors, and other components is essential for troubleshooting and maintenance. Mislabeling or inadequate labeling can lead to confusion and increased maintenance time.

Inadequate testing

Testing is an essential part of the design process to ensure that the harness performs as intended. Inadequate or incomplete testing can lead to issues that may not be discovered until the harness is in use, resulting in costly repairs and downtime.

By avoiding these common errors, designers can ensure that the wiring harness performs reliably over its lifetime, minimizing the risk of failure and reducing maintenance costs.

Types of wire harness components

Wire harnesses are collections of electrical wires, cables, and subassemblies that are covered by exterior sheaths and used to connect devices to their power source. The internal components are organized and protected from environmental hazards like moisture and physical damage by their sheaths. The most important parts of a wire harness are:

Wire: The signal or current that powers a device is carried by the wire. The voltage or bandwidth that the wire is expected to transmit must be met or exceeded by its capacity. The majority of wires are copper, and they can have a coating of your choice.

Connectors: To connect various types of wires, wire connectors are available in a variety of sizes and varieties. They are typically made of plastic, but they can also be made of ceramic and metal.

Fuses: Fuses prevent power surges from damaging or overloading devices on their receiving side. Different types of fuses are utilized by various harnesses. They typically have a rating of 32 volts or less, but this can change depending on the amperage they have.

Grommets: Insulators, grommets prevent moisture from entering the connector. A grommet can be a part of the connector or be attached to the terminal by itself. 

Outer coverings/Insulators: Insulators, also known as tubes and sleeves, offer protection from electrical shock, environmental protection, and some degree of abrasion resistance. They can be made of nylon or polyolefin, among other materials. 

Relays: Higher amperage circuits are turned on and off by relays. Harnesses are able to power multiple things because of this quality. They differ according to the required amperage, just like fuses. 

Strain Relief: Typically added to the connector's exterior. It is made to stop the force that pulls on the wires in the connector from pulling on the terminal, which could cause a bad connection. At extreme bend radiuses, strain relief can also be added, which can put an excessive amount of force on the wire and the connector's terminal. 

Terminals: The metal components that are attached to the end of the wire to be inserted into the connector or to a point on the connecting equipment are referred to as terminals.

Ties: The wires that are contained within the harness are held in place in a particular direction by cable ties and clamps. Additionally, it can be applied to a fixed structure to limit movement. 

Locks: To prevent the wire's terminal from being pulled out of the connector, locks are inserted into it. It can also guarantee that the terminal is fully inserted into the connector.


It can be difficult to create an electrical drawing for your application that includes all of the necessary information, such as schematics, harness layouts, and service documentation. It necessitates a thorough understanding of all components and influencing factors, not the least of which is an understanding of electrical requirements and limitations. Sedin Engineering, an expert company specializing in electrical assemblies, can assist in streamlining the procedure and making your final product more effective and efficient. For assistance keeping your project on track, take a look at our wire harness design services.

Need end-to-end engineering services to improve your business?
Learn here