Here at CDC, we’re the leading UK manufacturer of an extensive range of cables, including access control cables, EV cables, data cables, marine cables, multicore cables, and our bespoke, made-to-order custom cables. Another one of our specialities is the design, construction and enhancement of armoured cables, including the traditional steel wire armoured (SWA) cable and the more flexible galvanised steel wire braid (GSWB) cable.
Looking for an armoured cable solution to provide enhanced mechanical protection in underground power network, offshore, and instrumentation applications? Both GSWB and SWA cables are widely used in these sectors, but their strengths and uses are a bit different. Keep reading to learn more about the similarities and differences between GSWB cables and SWA cables.
What is an SWA cable?
Steel wire armoured cable is a traditional type of armoured power cable that’s designed for the supply of mains electricity, as it’s hard-wearing enough to be installed in underground power networks. An SWA cable is constructed from a multicore power cable covered by a protective layer of galvanised steel wires, which are wrapped (not braided) around the internal construction for maximum coverage – usually a minimum of 90% coverage. This provides a huge amount of mechanical protection for the internal conductors. Then, an outer insulating layer, such as a polyvinyl chloride (PVC) sheath, is added on top of the armour to keep all components together and provide additional protection.
One disadvantage of this extreme strength and durability is that these cables aren’t very flexible, which makes them unsuitable for applications where movement and flexibility is required. SWA cables are also heavier than other types of armoured cables and therefore more difficult to install.
What are SWA cables used for?
As you may imagine, steel wire armoured cables are ideal for any application where flexibility is not a necessity but a high level of mechanical protection is. For example, this durability allows SWA cables to be installed outdoors or even underground and underwater, since it can resist extreme weights, water, drilling, digging and rodent attacks. As a result, SWA cables are commonly used for underground power applications like mains power networks, underground transport networks and sewage systems.
SWA cable properties
SWA cable is an extremely heavy-duty cable with immense mechanical strength and low flexibility. Steel wire armour is applied to multicore power cables for mechanical protection, and other materials used in the construction of these cables include:
- Cross-linked polyethylene (XLPE) for insulation (thanks to its electrical properties and water resistance)
- PVC as bedding material to provide boundaries between inner and outer layers of the cable
- An outer PVC sheath to hold everything together and provide additional protection
The steel wire armour can also be used as the circuit protective conductor or CPC (commonly known as an ‘earth wire’) for the equipment supplied by the SWA cable, providing extra safety for the whole network.
What are GSWB cables?
Galvanised steel wire braided cables are a more lightweight and flexible alternative to traditional armoured cables like SWA cable. The key difference is that the steel wires are braided around the cable cores to create the armoured layer rather than twisted together, which means that overall there is less coverage of the inner layers (usually a minimum of 80%). Plus, this braided and woven pattern allows the cable to bend more easily without losing protection, unlike SWA cables which are much stiffer and harder to bend.
The diameter of the steel wires and the number count can be customised to adjust the levels of mechanical strength and flexibility provided. Fewer and thinner wires will produce a lighter, thinner armoured cable that’s more flexible and easier to install, whereas a thicker armoured layer will naturally increase the diameter and strength of the cable at the cost of some flexibility.
What are GSWB cables used for?
GSWB cables are commonly used in applications where flexibility and resistance to mechanical wear and tear are needed, in addition to weight and diameter savings compared to traditional SWA cables. For example, these armoured cables are frequently used to install power networks in marine and offshore environments because of their ability to withstand these harsh conditions while remaining relatively easy to install, move and bend. They can also be used in machinery production environments, instrumentation and control.
GSWB cable properties
GSWB cable features a variety of properties that make it suitable for a wide range of applications, and these properties include:
- Braided steel armour for strength and flexibility, as coverage is maintained even when the cable is bent
- Resistance to stress, flex and mechanical wear and tear
- Ability to be flexed and bent without deforming over time
- Corrosion resistance thanks to the galvanisation of the steel wires, making them suitable for marine and outdoor applications
- Resistance to cuts, chipping and scratches due to robust armouring
- Easier installation than traditional SWA cable due to its lighter weight and smaller diameter
- Ability to adjust the level of mechanical strength and flexibility by adding more steel wires or increasing their diameter
Other types of braided and armoured cables
However, not all applications are suitable for either GSWB or SWA cables. Other armoured cable options include:
1. LSZH cable
Low Smoke Zero Halogen (LSZH) cables are often used instead of SWA cables in public areas due to their ability to resist fire and not produce toxic smoke. LSZH cables are fire-resistant cables that are designed for use in public areas where potential fires and smoke inhalation would be extremely hazardous. As their name suggests, LSZH cables produce very little smoke if a fire does occur, and their materials don’t contain any toxic halogens that could cause serious health risks if released into the air. Cables used in highly populated areas must meet British standard BS 6724, meaning they must be constructed from LSZH materials (e.g. LSZH bedding and a black LSZH sheath rather than materials containing halogens).
2. AWA cable
Aluminium wire armoured (AWA) cables can sometimes be used instead of SWA cables. Steel wire armour is generally only applied to multicore cables, whereas aluminium can be applied to single-core cables. This is because a magnetic field is created by the current of a single-core cable, and since aluminium is non-magnetic, this prevents the cable from overheating. Since AWA cables are lighter than SWA cables (but still very robust), they can be used for power transmission over long distances and for various types of underground power networks.
3. Shielded cable
GSWB cables are suitable for applications requiring mechanical protection, but not those requiring protection from interference from external sources. In these cases, EMI (electromagnetic interference) cable shielding is needed to maintain signal integrity. To create a shielded cable, a fine wire mesh – typically in the form of multiple plain or tinned copper fine wire strands that are woven together – is applied over the twisted conductors. This creates a screen around the conductors to block interference and improve their performance. Plus, this screen will provide some mechanical protection, which is very useful in harsh environments such as manufacturing facilities.
4. SY cable
SY cable is another type of industrial armoured cable that guarantees both flexibility and mechanical strength. This type of cable is constructed from GSWB cable covered in a transparent PVC sheath, which means you get the same fantastic benefits of GSWB cable plus extra coverage and protection. In addition, thanks to the transparent sheath, you can see any corrosion or damage to the cable straight away, helping you improve health and safety procedures on your site. SY cables are often used for instrumentation, production and assembly lines, and the power generation industry.
5. CSTA cable
Corrugated steel tape armoured (CSTA) fibre optic cables are commonly used in the telecommunications industry. Corrugated steel tape armour is a more lightweight and flexible alternative to SWA, which means it can be installed more quickly and easily. This cable armour boasts excellent crush resistance and particularly good resistance to rodent attacks, making it very suitable for underground burial.
Custom Designed Cables supplies a wide range of armoured and braided cables for various industries, including marine and offshore, agriculture, audio/visual, instrumentation, food production and much more. We also work closely with our customers to tailor their cable solutions to better suit their environments and uses, such as by adjusting the coverage and diameter of braided wire armour. As part of our cable enhancements service, we can also customise existing cables with new jacketing in a range of colours and materials, and with custom branding if desired.
Get in touch today to enquire about costs and lead times – we guarantee you won’t find a more cost-effective, swift or personalised service elsewhere!
