Cable Assemblies, Wiring Harnesses and Wiring Looms: What is the difference?

Introduction

Cable assemblies, wiring harnesses (or wire harnesses) and wiring looms are all terms that are used interchangeably. However, they are in fact very different and it is these differences that dictate how they are used. Whilst it is true that all three have similarities in that they transfer electronic power or data signals between two points while also ensuring the wiring is kept tidy, as you will see below each option has its own unique features and benefits.

Firstly, one area which is sometimes misunderstood but is quite an important step in understanding the three wiring systems is the differences between a wire and a cable. A wire is a single conductor made up of a single or multiple strands of conductive material, usually Copper or Aluminium, which is protected by a non-conductive sheath generally made from thermoplastic. A cable is a collection of wires, usually with different coloured sheaths for easy identification, that are bound together inside an external cover. Again, this is an insulator made from material such as rubber or thermoplastic.

We will now look at the various wiring systems individually to highlight the differences between cable assemblies, wiring harnesses and wiring looms.

Wiring Harness

We will start with wiring harnesses as these are the most simple form of wiring system. A wiring harness is used as a method of keeping many wires tidy while following a predefined layout. The most basic example of this would comprise of several wires of the required length, which are bound together to save space and prevent damage during use. They may or may not be terminated by one or more connectors. A more complex harness may have wires going in multiple directions and include many different termination components.  The wires in both simple and more complex harnesses are usually bound together with materials such as heat shrink, cable ties or electrical tape. The production of these harnesses is normally quite simple, and therefore they can be produced quickly and at a reasonable cost. The benefit of a wiring harness is that the wires are kept neatly in place while also being visible so faults can be traced easily, and the binding of the wires helps to make the assembly more robust.

Cable Assembly

A cable assembly is very similar to a wiring harness in that it follows a predetermined layout and neatly holds a number of wires together, however, a cable assembly can incorporate both individual wires and multicore cables within its design. The main difference between a cable assembly and a wiring harness is that in a cable assembly, the wiring system is placed within an outer protective sheath that is generally produced from vinyl, rubber, polyurethane or heat-shrink plastic. The purpose of the sheath is to protect the wires and cables within from exposure to the elements, such as extreme temperature, fire, moisture, chemical substances and physical damage.