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TELECOMMUNICATIONS - MINIMUM CONDUCTOR SIZES FOR BONDING ?

 

The Wiring Rules AS/ACIF S009:2006 specify particular conductor sizes and cable colouring for different earthing systems and component parts. These requirements are relatively simple to follow however, they do change and you must refer to the most recent AS Wiring Rules.

 

 

 

The bottom line here is, we are not 100% of the time able to keep up with the ever changing field of Wiring Standards editions and mandates and you should perform more due diligence and research about your particular installation when considering sizes of earthing or bonding conductors.

The best way to solve this, is to simply purchase the latest edition.

Metal Barriers & Parts:-

Relevant Clause

Function Colour Minimum Size (cross-sectional area)

20.17

Earthing of metallic barrier to protective earth

Green/ Yellow

Minimum 2.5 mm²

20.19

Connection of a metallic cable tray, conduit, trunking system, distribution frame, backmount, enclosure, catenary support or the steel wire armouring of an SWA cable to protective earth

Green/ Yellow

Minimum 2.5 mm²
(except where used for connection of surge suppression for protection of end-users)

CES:-

20.11.2

20.12.4

Connection from the equipotential bonding point on the earthing system of the electrical installation to the CET (bonding method 1 or 2)or the bar, terminal or backmount of the distributor (bonding method 3)

Green/ Yellow

Size for allowable resistance
Minimum 6 mm²

20.12.2

20.12.4

20.20.1

Connection from the CET (bonding method 1or 2) or the bar, terminal or backmount in the distributor (bonding method 3) to any distributor or other connection device that contains surge suppression for the protection of end-users

Green/ Yellow

Size for allowable resistance
Minimum 6 mm²

20.12.2

20.12.4

20.20.2

Connection from the CET to any distributor or other connection device that does not contain surge suppression for protection of end-users

Green/ Yellow Size for allowable resistance
Minimum 2.5 mm²

20.11.2

20.12.4

Connection from any distributor to any other distributor or CAE earthing bar or terminal

Green/ Yellow Size for allowable resistance
Minimum 2.5 mm²

 

 

TRC:-

20.11.2

20.13.9

Connection from the equipotential bonding point on the earthing system of the electrical installation to the TRC link bar at the designated distributor

Green/ Yellow

Size for allowable resistance
Minimum 6 mm²

20.13.5

20.13.11

Connection from the TRC link bar of any distributor to the TRC link bar of any other distributor or CAE

Violet Size for allowable resistance
Minimum 2.5 mm²

20.13.8.5

TRC connection from the designated distributor to a TFEE (where provided)

Violet

Minimum 4 mm²

Surge Supression:-

20.11.2.1

20.11.2.4

20.20.1

Connection of a surge suppression device for the protection of end-users

Green/ Yellow Size for allowable resistance
Minimum 6 mm²

20.20.2

Connection of a surge suppression device for the protection of customer equipment

Green/ Yellow Minimum 2.5 mm²

Labelling Earthing Systems:-

The Wiring Rules AS/ACIF S009:2006 specify certain labelling requirements for earthing systems. These requirements are as follows:

  • The bonding conductor shall be labelled at the electrical installation end, e.g. 'Communications Bonding Conductor', and also at the telecommunications earthing system end where both ends of the bonding conductor are not readily identifiable.
  • The CET shall be marked 'Communications Earth Terminal'.
  • The TFEE shall be permanently labelled 'Telecommunications Electrode'.
  • Where the maximum limiting voltage of the differential earth clamp exceeds ELV, all TRC link bars and terminations shall be suitably labelled to warn workers of possible voltage differences between the TRC and protective earth. See example below:
" WARNING! This TRC is not directly bonded to the electrical earthing system. A hazardous voltage may exist between the TRC and other earthed objects "

 

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This page was last modified on 23 January 2010 and maybe out of date with regards to newer practices or tariffs at the time of reading this article. The information above is only intended for use a guide and should not be relied upon as a substitute for technical advice. Quality Electrics disclaims responsibility for any damage, claim, or liability any person may incur, whether caused by negligence or otherwise, as a result of anything contained in our articles.

 
 
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