Example of steel wire armoured cables in a UK installation. Blue sheathed cable is normally instrumentation signal, black is power The typical construction of an SWA cable can be broken down as follows: Conductor: consists of plain stranded copper (cables are classified to indicate the degree of flexibility. Class 2 refers to rigid stranded copper conductors as stipulated by British Standard BS EN 60228:2005) Insulation: Cross-linked polyethylene (XLPE) is used in a number of power cables because it has good water resistance and excellent electrical properties. Insulation in cables ensures that conductors and other metal substances do not come into contact with each other. Bedding: Polyvinyl chloride (PVC) bedding is used to provide a protective boundary between inner and outer layers of the cable. Armour: Steel wire armour provides mechanical protection, which means the cable can withstand higher stresses, be buried directly and used in external or underground projects. The armouring is normally connected to earth and can sometimes be used as the circuit protective conductor ("earth wire") for the equipment supplied by cable. Sheath: a black PVC sheath holds all components of the cable together and provides additional protection from external stresses. The PVC version of SWA cable, described above, meets the requirements of both British Standard BS 5467 and International Electrotechnical Commission standard IEC 60502. It is known as SWA BS 5467 Cable and it has a voltage rating of 600/1000 V. SWA cable can be referred to more generally as mains cable, armoured cable, power cable and booklet armoured cable. The name power cable, however, applies to a wide range of cables including 6381Y, NYCY, NYY-J and 6491X Cable.