Guide to Cables

Reviewed by Jay Proctor, Technical Support Team Leader (March 2024)

This guide aims to provide valuable insights into the multifaceted world of cables. You will learn everything you need to know about cables, from the differences between various types of cables to the best uses for each. We will also discuss cable safety and key regulations, as well as cable selection considerations.

Different types of cables are used in various applications, each selected based on their specific properties and capabilities. 

Let's explore the uses of some common cable types:

1. Power cables: These cables transport electrical power from one point to another. They are commonly used in residential, commercial, and industrial settings to supply electricity to buildings, machinery, and appliances
2. Data cables: Also known as communication cables, these cables transmit data signals between devices. They are widely used in computer networks, telecommunications systems, and audio/video applications
3. Coaxial cables: Coaxial cables transmit high-frequency signals with low loss. They are commonly used in TV systems, CCTV installations, and high-speed internet connections
4. Ethernet cables: These cables connect devices in local area networks (LANs) to facilitate data transfer. Ethernet cables are widely used in homes, offices, and data centres
5. HDMI cables: HDMI (High-Definition Multimedia Interface) cables transmit high-quality audio and video signals between devices. They are commonly used in home theatre systems, gaming consoles, and multimedia devices
6. USB cables: USB (Universal Serial Bus) cables are used for connecting devices like smartphones, tablets, printers, and cameras to computers or power sources. They facilitate data transfer and device charging

These are just a few examples of the wide range of cable applications. Depending on the specific requirements of a project or application, different types of cable should be used to ensure optimal performance and reliability.

In the UK, there are specific cable regulations in place to ensure the safety, reliability, and performance of different types of cables used in various applications. These regulations outline the naming and coding system for cables, and British standards for design and manufacturing.

The naming and coding system for cables provides a standardised way to identify and categorise different types of cables. It assists users, engineers, and installers in quickly recognising a cable’s purpose and characteristics based on its name or code. This system includes abbreviations and codes representing specific features such as the conductor material, insulation type, voltage rating, and more.

British standards play a crucial role in ensuring cable quality and safety. These standards define the requirements that cables must meet to be considered compliant. They cover aspects such as fire performance, mechanical strength, chemical resistance, and environmental factors. Adhering to British standards is essential to guarantee cable suitability and reliability for their intended applications.

• British Standards: PVC insulated cables to BS4808 are designed for the internal cabling of electrical and electronic equipment and are also used for wiring within instrumentation and control panels. BS EN13062 compliant wire is of a tinned annealed copper construction suited for use as rewireable fuse links, shorting links, etc
• DEF STAN: Cables designed to meet the requirements of DEF STAN 61-12 Part 29/1 are used typically in high-demand applications found in military, avionics, aerospace, nuclear, and medical environments
• Harmonised: Compliant with European Harmonised Standards H05V-K and H07V-K, harmonised cables are colour-coded PVC sheathed cables with a single-stranded untinned copper core. Harmonised cable is widely used in lighting, wiring installation work within control and distribution panels, conduits, and channels. First introduced in 2004, the harmonised colour code differentiates between conductors in single and three-phase circuits
• MIL SPEC: Cables designed to military specifications and compliant with MIL-W-81822/13 are single-cored with PVC or PTFE insulation. Specially designed for harsh environments, they are used in aerospace and similar industries where a high degree of tolerance to chemicals and radiation may be required. They can be used in high-temperature and high-frequency applications. MIL SPEC cable lends itself to both soldered and wire wrap work and should be used when challenging conditions demand strong durability
• UL Standard: These cables meet UL (Underwriters Laboratories) testing classification. This is a category of cables and wire that has been tested independently to conform to requirements for use in a variety of applications, including general-purpose wiring circuits, control circuits, and internal appliance wiring. Cables manufactured to UL Standards have single-stranded cores and are available in a variety of colours with four sheath constructions. A wide range of cables and wires meet UL standards and it is UL’s evaluation of the product that determines its area of use

When dealing with cables, safety should always be the priority. Cables are integral components of various electrical systems, and understanding their safety features, potential hazards, and safe usage methods is crucial to preventing accidents and ensuring equipment longevity.

Cables come with a range of safety features to protect users and equipment. Some common safety features include insulation, shielding, and grounding. Insulation reduces the risk of electric shock by covering the conductive parts of the cable with non-conductive material. Shielding minimises electromagnetic interference, ensuring cable performance is not affected by external factors. Grounding provides a safe path for electrical energy to dissipate, reducing the risk of electrical faults.

Despite these safety features, cables can still pose potential hazards if not used correctly. Some hazards include tripping over loose cables, overloading cables with excessive current, or using damaged cables. To avoid these hazards, it's important to keep cables properly organised and secured, ensuring they are not left in walkways or areas where they can be damaged. Additionally, it's crucial to follow the manufacturer's guidelines for current ratings to prevent overloading. Regularly inspecting cables for damage, such as frayed insulation or exposed wires, is also essential for safe use.

Here are some general tips for using cables safely:

• Always use cables appropriate for the intended purpose and environment
• Avoid bending cables excessively, as this can damage internal conductors
• Do not pull cables from their connectors to disconnect them; instead, grasp the connector firmly and disconnect it
• When unplugging cables, hold the connector firmly and pull straight out

By following these safety guidelines, you can ensure safe and efficient cable use in your electrical systems.

Cable screening is a necessity in many wiring applications. Screening protects a conductor from external interference or EMI, prevents radiation from the cable itself, and minimises cross-talk between conductors.

Various degrees of screening are used according to cable type and application. From unshielded power or control cable used in areas not prone to interference, e.g. within a metal control cabinet, to foil or braided shielded cable for areas of high EMI or electrical interference.

When buying cables, there are some key things to consider. As well as selecting the correct cable type for your application and environment, you need to bear in mind:

• AWG (American Wire Gauge) is a widely accepted measure of wire cross-sectional area denoted as a simple number
• CSA (Cross Sectional Area) is the surface cross-sectional area of a conductor in mm²

Both units of measurement are used in determining wire thickness. It’s useful to remember that as the AWG increases, the wire becomes thinner and the CSA decreases. 

An approximate conversion between AWG and CSA is shown below for selected sizes:

The complete AWG wire range contains over 40 sizes with respective cross-sectional areas and current carrying capacities.

• Solid Core: Solid core wire consists of one single core, usually copper, forming an insulated conductor. It has a higher resistance to flexing than stranded wire so it’s best suited to permanent and semi-permanent wiring. Solid core cable costs less to manufacture than stranded core and has higher electrical resistance
• Stranded Core: For a given gauge, stranded wire withstands flexing more than its solid core equivalent. Stranded wire is best suited where frequent flexing or vibration is more likely to occur, e.g. automotive applications, flexible power cables, or signal wiring in electrical and electronic devices. It has a higher attenuation than solid core so is not best suited to long cable runs

At RS, we offer a vast range of cables to cater for various applications and environments. Our RS PRO range brings you high-quality, professionally approved products, while our wide choice of market-leading brands is second to none. 

Whether you need AV cables, computer cables, electrical cables, coaxial cables, or single-core cables, you can find a comprehensive selection of high-quality products on our website.