to the 16th Edition IEE Regulations
   
   
   
 
 

chapter 5
Earthing

chapter 6
Circuits

Data cabling and networks
  9.1 - What is data cabling and why do
------- we need it?
9.4 - System design and categories

  9.2 - What are digital systems? 9.5 - Installing data cabling
  9.3 - Copper or glass fibre? 9.6 - Useful information


9.6 - Useful information

Data cabling was first used in the USA, and as a result most of the terms used were coined there. Since they may not always be familiar to the installation electrician, some of the most common terms are defined in Table 9.3

Table 9.3 - Some data cabling terms explained
Attenuation A reduction in power or amplitude of the transmitted signal. In cables, usually expressed in decibels per unit length.
Attenuation to crosstalk ratio (ATR ) The difference between attenuation and crosstalk measured in decibels.
Backbone cabling Cable and connecting hardware that comprise the main and intermediate cross-connections (often known as ”cross-connects“).
Bridged tap The multiple appearances of the same cable pair or fibre at several distribution points.
Channel The end-to-end transmission path connecting any two points to which equipment is connected.
Cross-connection A connection scheme between cabling runs, subsystems and equipment using patch cords or jumpers that attach to connecting hardware at each end.
Crosstalk Noise or interference caused by electromagnetic coupling from one signal path to another and usually expressed in decibels.
Decibel (dB) A standard unit to express transmission gain or loss as derived from a ratio of signal amplitudes or power (see Table 9.13).
Equal level far-end cross-talk (ELFEXT) Crosstalk measured at the opposite end from which the disturbing signal is transmitted normalised by the attenuation contribution of the cable or cabling.
Far-end crosstalk (FEXT) Crosstalk measured at the opposite end from which the disturbing signal is transmitted.
Fibre optic transmission A communications system where electrical data are converted to light energy and transmitted through optical fibres.
Horizontal cross-connect (HC) A cross-connect of horizontal cabling to other cabling, such as horizontal, backbone or equipment.
Hybrid cable An assembly of two or more cables, of the same or of different types or categories, covered by one overall sheath.
Jumper wire An assembly of twisted-pairs without connectors on either end used to join telecommunications links at a cross-connect.
Near-end crosstalk
(NEXT)
Cross-talk measured at the end from which the disturbing signal is transmitted.
Patch cord A length of cable with connectors on one or both ends used to join telecommunications links at a cross-connect.
Private branch exchange (PBX) A private switching system usually serving an organisation, such as a business, located on the customer’s premises.
Propagation delay The amount of time that passes between when a signal is transmitted and when it is received at the opposite end of the cable or cabling
Punch down A method of securing wire to a quick clip, in which the insulated wire is placed in the terminal groove and pushed down with a special tool. As the wire is seated, the terminal displaces the wire insulation to make an electrical connection.
Quick clip An electrical contact used to provide an insulation displacement connection to telecommunications cables.
Ring conductor The unearthed (ungrounded) conductor of the two in a cable pair.
Screened twisted-pair (ScTP) A balanced twisted-pair cable surrounded by metallic braid, foil, or both, and bound in a single cable sheath.
Shielded twisted-pair
(STP-A)
A cable surrounded by a metallic braid, foil, or both, and bound in a single plastic sheath containing balanced twisted-pair conductors that are individually sheathed.
Tip conductor The earthed (grounded) conductor of the two in a cable pair.
Unshielded twisted-pair (UTP) A cable with multiple pairs of twisted insulated copper conductors bound in a single sheath.
Webbed conductors The manufacturing process that physically binds the conductor insulation of the wire pairs of an unshielded twisted-pair cable.

 

 

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Extracted from The Electricians Guide Fifth Edition
by John Whitfield
Published by EPA Press Click Here to order your Copy

Click here for list of abbreviations