Twisted-Pair Data Cable (UTP/STP/FTP Shielding)

Signal or data cabling built up from several pairs of conductors twisted together, where the twisting primarily serves to make the interference voltage induced electromagnetically in both conductors of a pair equal, so that with differential signal transmission they largely cancel each other out; the shielding code indicates what additional protection has been applied on top of that: UTP (Unshielded Twisted Pair) has no shielding, FTP (Foiled Twisted Pair) has one shared foil shield around all pairs, and STP/SFTP (Shielded/Screened Foiled Twisted Pair) has both a braided screen layer and individual foil shielding per pair, for the highest EMC immunity. For building installations with mixed power and data cabling, such as building management systems (BMS), access control and EIB/KNX bus systems, the degree of EMC exposure (proximity to power cables, variable-frequency drives) determines which shielding class and separation distance from power cables are required, and a shielded cable must always be correctly earthed at one end (or, for long runs, at both ends with a dedicated earthing strategy) for the shielding to actually be effective — a loose or unconnected screen provides no protection and can even start acting as an antenna.