Published On: April 24, 2018

Wire harness partsThe ideal wiring harness is only as good as its wiring harness components and the operating conditions it is made for. Therefore, what kind of components to use in manufacturing the wiring harness, and how many, will be determined by the application as well as the environmental conditions that the product is intended for.

Step 1: What Will Your Wire Harness be Used For?

Wiring harnesses are utilized in many industries to simplify the manufacture of a larger component. They are necessary in the manufacture of appliances, medical equipment, and electronic equipment. They are used in telecommunication equipment, various military, aviation, and aerospace applications, in the building of robotics, and can be found in every type of vehicle.

Depending on the design, a wire harness can have dozens of wires and dozens of different components consisting of multiple branches and ends, going in different directions with multiple terminations on each branch. The wiring harness functions by relaying, allocating, and directing information via electrical signals throughout the entire system. Once assembled, wiring harnesses allow for easy drop in installation and product kitting.

Step 2: What Conditions Will Your Equipment Need to Endure?

That said, environmental conditions play a vital part in determining what type of components will be used in the wiring harness. In most cases, you should make 2 major considerations:

  • Will the wiring harness be used indoors or outdoors?
  • Will it be exposed to moistureliquids, or chemicals?

It’s important to anticipate these questions and others like them during the product development stage. This is where choosing an experienced OEM (Original Equipment Manufacturer) for your product becomes important. Seek an OEM that has the knowledge and know-how to anticipate and guide your company in selecting wiring harness components that will meet your product requirements.

Step 3: Choosing Wire Harness Components

Components for your wiring harness include a conductor, connectors, terminal, grommets, strain relief, cabling, and its jacket or insulation. Let’s take a closer look:


Conductors transmit the currents or signals through the wire harness. Its carrying capacity should not exceed the voltage or bandwidth. Doing so could potentially result in overheating or weaken the transmission. Copper is the best metal to use because of its high conductivity. However, because copper is subject to corrosion, know what environmental conditions the conductor will be exposed to determine the appropriate coating to resist it.


A terminal is that part of the wire harness where the wire ends, is connected to another component, or is simply capped. Any of these roles depends on where the terminal is located or how it will be used.


There are a variety of connectors used to marry different wires together. Some of these are permanently affixed to the system, while others are removable for products that are likely to be portable or require interchangeable parts.

Strain Relief

Wire harnesses are designed to be flexible. However, harness connection points, where the wire meets connectors or plugs, need to be rigid. The strain relief is necessary to withstand the stress and tension and other flexural forces the harness is subjected to at its connection points.  The strain relief is an essential feature to maintain system wire harness integrity and its overall performance.


Utilizing grommets will keep wires secure and in their proper place. Grommets help to maintain an organized system and will make installation and any maintenance on the product more efficient.

Insulation Jacket

Insulation serves as an efficient solution to protect wires within a harness assembly. An insulation jacket protects the wire from detrimental conditions such as chemical or oil leaks, water, moisture, extreme heat or cold. Typical insulation options include PVC, rubber, cross-linked and polyurethane thermoplastic.

Choosing the right components for your wiring harness is vital to ensuring that you have a product which meets your design standards and runs efficiently. It is crucial in building a wiring harness that will perform reliably. Distance, carrying capacity, and types of insulation are some of the important considerations in your design, as is the environmental conditions the wiring harness system will be operating in. When selecting an OEM, entrust your product with an experienced manufacturer that understands your company’s individual needs and your product’s specifications.

JEM Electronics has been manufacturing high quality custom wire harnesses and assemblies with on-time delivery and superior lead times since 1981, with the capability to help with everything from harness design to electrical prototyping and safety testing. Contact us today to get started on your next project!

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