Metallic wires and cables
Most generally available cables are manufactured to recognized standards which may be national, European or international. Each defines the construction, the type and quality of constituent materials, the performance requirements and the test methods for the completed cable.
The IEC standards cover those cables which need to be standardized to facilitate world trade, but this often requires a compromise by the parties involved in the preparation and acceptance of a standard. Where cables are to be used in a particular country, the practices and regulations in that country tend to encourage the more specific cable types defined in the national standards for that country. BS remains the most appropriate for use in the UK, and for the main cable types described in this chapter reference has therefore been made mainly to the relevant BS.
Some cables rated at 450/750 V or less have through trade become standard throughout the EU, and these have been incorporated into Harmonization Documents (HDs). Each EU country must then publish these requirements within a national standard. A harmonized cable type in the UK for instance would still be specified to the relevant BS and the cable would, if appropriate, bear the <HAR> mark.
The key standards for metallic wires and cables which have been referred to in the chapter are listed in Table 9.1.
For communication systems and their evolution to be effective, standardization must be at an international level. Optical fibre and cable standardization in IEC started in 1979. The ENs which have been published generally use IEC standards as a starting point but they incorporate any special requirements for sale within the EU where European Directives may apply.
Table 9.2 summarizes the main standards in the areas of optical fibres, optical cables, connectors, connector interfaces and test and measurement procedures for interconnecting devices.