Cable Terminations: Everything You Need To Know

The purpose of any cable connection is to transfer a seamless electrical signal via a mechanical connector, with minimum loss of performance. 

When installing any type of wired device, you’ll end up with a continuous line of cable connecting all the various sections. The points where these connections occur are the cable terminations. At each end of any cable they’re called terminal heads, whereas if a cable is spliced in the middle, they’re known as intermediate splices. 

Why Use Cable Terminations?

There’s an argument that pure wire-to-wire connections offer the best electrical contact, so a better circuit connection is achieved. But twisting uninsulated wires together and fixing electrical tape over them isn’t a reliable or safe way to connect devices. It should only ever be a stop-gap measure. A more permanent solution is to solder the wires together – a tried-and-tested method proven over the long term in industrial electrical engineering. 

Applying liquid solder to a joint fuses the cable ends and the solder then solidifies to create a durable, electrically-efficient and low-resistance connection. Soldering a joint also makes it air-tight, insulating it against possible oxidisation of copper conductors. But soldering can be labour-intensive, making it a better solution for low-volume or high-density connections.

There are several advantages to using cable terminations over bare or soldered joints, including:

• Improved safety

• Enhanced durability

• Better electrical performance

• Ease of installation and maintenance

Cable terminations are a lot easier to install and maintain, safer and more efficient. You’ll get a better connection and less likelihood of signal leakage or interruption, so your applications will work more efficiently and for longer. As well as forming a seamless electrical circuit, cable terminations seal the cable’s connection points. This helps insulate the power line from dust, dirt, water and vibration, ensuring it operates reliably.

Cable Termination – Methods and Types

Other common connection methods include crimping, compression, wire wrapping and insulation displacement. To help you make an informed decision when selecting cable terminations, we’ll look at the range of methods and the most common choices of termination type. We’ll also outline their most common use cases and highlight their advantages. 

Crimped Terminations

Crimped terminations are a popular choice, providing a robust and efficient connection method for a wide range of materials and sizes. You’ll need a crimping tool to connect conductors in this way, which will compress and tightly secure a ferrule or metal sleeve around the conductor.

This compression creates an electrically conductive, air-tight joint that offers considerable mechanical strength, as it resists movement, vibration and pull-out forces. Its popularity lies in its long-term reliability and suitability for high-volume production, as the process is fast and repeatable. To achieve the best results, purchase the appropriate crimping tool and terminals for each conductor and application.

Compression Terminations

This method relies on compressive forces to make secure cable connections, such as mechanical connectors with set screws or bolts. This type of termination is good for high voltage and current applications, as it offers excellent conductivity and minimal resistance. It can stand up to environmental exposure and thermal cycling, is simple to connect and disconnect and is reusable.

The drawback to compression terminations is that they’re time-consuming, especially if you have multiple conductors. You have to tighten the connectors according to specified torque values to get the best performance and durability, or they may work loose over time. To avoid damage to the conductors, you need some skill to install compression terminations correctly.

Wire Wrap Terminations

Wire wrap terminations are often used in electronics. They offer a unique way of making connections on items like integrated circuits and connectors and are fairly reliable for small-scale projects like rapid prototyping. This technique requires a wrapping tool, which secures a thin, solid wire in place around a conductive post or pin. The tool has sharp edges that penetrate the wire’s insulation, creating a temporary air-tight connection.

Insulation Displacement Terminations (IDTs)

IDTs offer an efficient and convenient termination method, which eliminates the need to strip off cable insulation. The connector is fitted with sharp teeth or blades that pierce the cable insulation to make direct contact with the core of the conductor. It’s faster and easier than the traditional way of stripping insulation and is often used in domestic environments as well as data cabling and telecommunications.

Other advantages of IDTs include a lower likelihood of accidentally damaging the conductor. They’re air-tight and work well in mass termination applications, although displacing the conductor’s insulation may cause some signal attenuation. 

Cable Termination – Types

Pre-Insulated Terminals

Description

Pre-insulated terminals consist of a metal body enclosed in plastic insulation. There are several types of pre-insulated terminals, including the tubular, circular or fork-type, and what are known as ferrules. These are usually some form of narrow circular ring that fits over the end of a stripped electrical cable. They’re typically made of metals like copper or aluminium, or sometimes plastic.

Purpose

You can insert wires into the holes provided at both ends of the terminal and tighten or loosen the connection with screws. It’s an easy way to connect or disconnect two wires without twisting or soldering them. It provides additional safety to equipment and users. 

When To Use

Pre-insulated terminals are widely used in industrial automation, especially in applications where insulation is critical to prevent short circuits or electric shocks. 

Advantages

The main advantages of pre-insulated terminals are that they’re quick and easy to install, provide good electrical insulation and reduce the risk of corrosion.

Bootlace Ferrules 

Description

Bootlace ferrules are copper tubes that fit on the end of a stripped cable. They’re available with or without an insulating end sleeve and are usually crimped over the stripped wires at the end of a cable to form a reliable electrical connection. 

Purpose

They provide optimum electrical contact, with no potential for wire strands to unravel, spread or break. This is especially important for small wire applications or those where the housing is frequently removed, such as control units, switch boxes, function units, screw and spring terminals, or row and terminal connectors. They also prevent any unwanted contacts being connected in the terminal, which removes the potential for short circuits.

When To Use

This type of termination doesn’t connect cables. It is used specifically for the end-point of a cable, where it protects the exposed wire strands. You’ll usually find it in control panels and other electrical installations that demand a secure and safe connection.

Advantages

Bootlace ferrules help to prevent wire strands from fraying. They simplify the insertion of cables into terminal blocks and ensure a solid and reliable connection.

Copper Tube Terminals 

Description

Copper tube terminals consist of a seamless copper tube that usually has a corrosion-resistant coating. This type of terminal is also known as a battery eyelet (as you’ll often find them on batteries) as well as eyelet terminals, starter rings and more. You’ll see a hole at the terminal’s end where you can connect a stud and a wide opening at the other end for easy cable insertion. 

Purpose

Copper tube terminals offer a high level of conductivity and so are ideal for heavy-duty industrial and high-current applications.

When To Use

You’d be most likely to use a copper tube terminal for terminating cables carrying higher currents, such as primary power feeds and main battery connections.

Advantages

Copper tube terminals offer excellent mechanical strength, combined with a high level of electrical conductivity and resistance to corrosion.

Copper Tube Splices 

Description

Copper tube splices are a type of intermediate cable termination that are often tapered internally at both ends to make inserting the conductors easier. Many also have a central stop point to help position both cables correctly. 

Purpose

These intermediate terminations are for joining together low-voltage conductors, so you can connect two cables together securely.

When to use

You’ll use this kind of terminal when joining cables together in a power distribution system.

Advantages

Copper tube splices are capable of handling high current loads. They are strong and reliable connections that are resistant to damage by environmental factors.

Copper Pin Terminals 

Description

Copper pin terminals are most commonly used as an easy method of connecting individual cables to terminal blocks. They usually combine a tube for the cable with a grooved profile pin that goes into the connector and easily connects wires and cables to an electrical system.

Purpose

Copper pin terminals make it faster and easier to insert cables into terminal blocks, especially in applications that require a clamp or screw.

When To Use

You’ll use these most commonly for connecting wires to a terminal block. They’re ideal for situations where frequent connection and disconnection are required.

Advantages

Their main advantage is simplicity of use, combined with good electrical conductivity and a reliable connection.

Aluminium Terminals 

Description

Aluminium terminals offer a more corrosion-resistant alternative to copper or other materials, especially when weight or environmental factors have an impact. They come in various forms, including crimped, compression or combination-type with copper. Aluminium connectors can be easily machined and are easy to process.

Purpose

Aluminium is lightweight and offers good conductivity.  It’s more resistant to corrosion than copper or other metals, so aluminium terminals are a good choice for outdoor applications. 

When To Use

You should use aluminium terminals if your cabling is also aluminium. Choose them also for applications where weight reduction is a factor or in difficult environmental conditions, including fire hazards.

Advantages 

Aluminium terminals offer a cost-effective, lightweight solution with good corrosion resistance.

Cable Terminations – Other Factors

There are additional ways to classify electrical cable terminations, depending on several factors. These include whether they’re to be installed in interior or exterior locations, what materials they’re made from and whether they’re a complete set or for intermediate electrical power cables. You can get cold or heat shrinkable installation types, or those installed using epoxy resin or dry wrap. Cable terminations are typically classified according to the operating voltage, ranging from 1kV to 220kV.

Terminations are also divided by what material the electrical cable is made of, such as copper or aluminium, and how many conductors they need. There’s even a range of sub-categories relating to the joint material, starting with a choice between plastic and metal, and subdivided into categories including flexibility and waterproof, anti-bending and double locking capabilities. 

Choosing The Right Cable Termination

Cable terminations come in many different designs and materials, with several different attachment styles. This can sometimes make it tricky to determine which one is right for your particular application. It’s important to use the correct termination so that both ends of the connector match and form a perfect bond. Incorrectly matched terminations might lead to short-term or intermittent functioning or complete circuit failure. Many international standards govern different types of cable and connections, so you need to assess your application needs carefully.

Prefabricated terminals are generally quicker and easier to install, requiring fewer tools. They’ll last longer and be more robust as well as easier to maintain. But you do need to select your cable terminations carefully according to the specific needs of your application. Some factors you’ll have to consider include:

• Electrical requirements such as the nominal voltage and rated current

• Environmental conditions such as ambient temperature and humidity

• Mechanical strength required

• Cost considerations, especially if a lot of terminations are necessary

Rowse Automation has many years of collective experience installing cabling and terminations, and we’re always happy to be of assistance. If you’d like any help with your projects or purchases, please give us a call.