4.5 Installation
4.5.1 General
4.5.2 Cable depths
4.5.3 Laying of cables
4.5.4 Separation of cables
4.5.1 General
Underground electric cables and underground control cables should be installed having regard to system reliability, ease of future maintenance and safety. Consideration should also be given to minimising damage to underground assets.
Basic factors to be considered during the installation of underground cables are set out in ESAA C(b)2.
4.5.2 Cable depths
The depth of cover for underground electric cables and underground control cables should not be less than:
For open trench construction:
- 750 mm below the surface of a roadway for any cable installed under a roadway; and
- 600 mm below the finished ground surface for cables installed in other locations.
Where physical obstructions such as other services make it impossible to achieve these depths, additional mechanical protection should be provided by means of a minimum cover of 100 mm of 20 MPa concrete or equivalent. Any additional mechanical protection should be marked with the words electric cable or similar along its length.
For trenchless construction:
- 900 mm below the finished ground surface.
4.5.3 Laying of cables
The technique used for installing underground cables should ensure that damage to the cables is negligible. Consideration should be given to:
- maximum hauling tensions;
- minimum bending and setting radii;
- cable side wall pressures; and
- cable abrasion avoidance.
4.5.4 Separation of cables
When determining minimum separation from telecommunication plant in a shared trench, refer to the Standards Australia manual CJC4-2000 Coordination of Power and Telecommunications.
Consult the authority concerned about separation from other services sharing the trench, keeping in mind:
- employee and public safety;
- potential cable damage due to failure of other services; and
- future access for repairs/maintenance.
Last updated July 21, 2005
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