There are so many different kinds of custom cable that it can be hard to differentiate between them; while some are named after their particular purpose (subsea cables, for instance), others have quite generic names that give no real clue to their application. One such example are steel wire armoured cables, or SWA cables for short.
SWA cables are multicore cables with a layer of steel wire armour, which provides protection from mechanical damage. SWA cables are used as power cables and are usually employed in applications where the cable has to be buried underground and in power networks. Quite simple really!
How are SWA cables made?
The construction of SWA cables is quite simple too. Here are the main components of an SWA cable:
Conductor: this is usually plain stranded copper. Multiple cores are used.
Insulation: insulation is used to protect the conductors from any water damage – a particular issue if the cable is buried underground. It also provides a barrier between the conductors and other metal components, such as the armour.
Bedding: PVC bedding acts as a buffer between the inner ‘live’ parts of the cable and the outer components.
Steel Wire Armour: the armour itself is placed over the bedding, providing the cable protection from stress. Sometimes, the armour can be used as the ‘earth’ cable.
Cable sheathing: a sheath is used to protect the inner components of the cable and provides further protection from mechanical damage and stress.
Where Are SWA Cables Used?
Armoured cable can be used for a vast array of applications, but is commonly associated with ‘underground’ applications, such as sewers and underground transport networks. When deployed in public places, the cable also has to feature LSLH (low smoke, low halogen) sheathing. This sheathing emits low smoke and halogen in case of a fire, making it a far safer alternative to standard cable sheathing.
You’ll only find steel wiring used in multicore cables. This is because steel is magnetic; when a current passes through a single core, a magnetic field would be produced. This would lead to a current also passing through the steel wire, which could in turn lead to overheating and potentially fire. As this is the case, aluminium is generally preferred in single core cables. For more information on steel wire armoured cables, get in touch with Custom Designed Cables.