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Copyright2008
TRENCHING AND CONDUIT STANDARD
FOR
UNDERGROUND CABLE NETWORKS
Technical Standard TS-085
Issued: December 2008
REVISION NOTICE
DATE SECTION EXPLANATION
Oct 06 4 & 5Modifications to clauses; 3, 4, 5, 7, 14 &
added Appendix B.
Dec 08
Added clause 13 associated with civil works
specific to 66kV cables and minor updates
and re-numbering.
ETSA Utilities ABN 13 332 330 749
a partnership of:
Spark Infrastructure SA (No. 1) Pty Ltd
ABN 54 091 142 380
Spark Infrastructure SA (No. 2) Pty Ltd
ABN 19
091 143 038
Spark Infrastructure SA (No. 3) Pty Ltd
ABN 50 091 142 362
each incorporated in Australia
CKI Utilities Development Limited
ABN 65 090 718 880
HEI Utilities Development Limited
ABN 82 090 718 951
each incorporated in The Bahamas
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CONTENTS
CONTENTS..................................................................................................... 1
1.0 DEFINITIONS ........................................................................................ 4
2.0 BACKGROUND ..................................................................................... 4
3.0 RETAINING WALLS ............................................................................ 5
4.0 TRENCHING.......................................................................................... 7
4.1 General .............................................................................................................. 7
4.2 Road Reserves and Road Crossings................................................................ 8
4.3 Requirements for Department of Transport, Energy and Infrastructure
Roads.................................................................................................................. 9
4.3.1 Open Trenching......................................................................................... 94.3.2 Trenchless Method.................................................................................. 10
4.3.3 Department of Transport, Energy and Infrastructure Notification ......... 10
4.3.4 Traffic Control Notification .................................................................... 10
4.3.5 Installation Details .................................................................................. 10
4.3.6 Emergency Work..................................................................................... 11
4.3.7 Maintenance Period................................................................................. 11
4.4 Installation of Conduits Within Railway Boundaries ................................. 11
4.5 Clearances between Services ......................................................................... 12
4.6 Changes in levels and directional changes ...................................................13
4.7 Common Service Trench................................................................................ 14
4.8 Trenching for Restrospective Undergrounding (eg PLEC schemes)......... 15
4.8.1 Pit Installations........................................................................................ 16
4.9 Location Marking of LV & HV Cable Trenches .........................................17
4.10 Trenchless/Directional Boring....................................................................... 17
5.0 CONDUIT REQUIREMENTS............................................................ 17
5.1 General ............................................................................................................ 17
5.2 Spare Conduit Provision................................................................................ 18
5.2.1 Wherever an electrical cable is buried direct, ie in a road reserve.......... 18
5.2.2 When a cable is installed in a conduit.....................................................18
5.2.3 Road Crossings........................................................................................ 19
5.3 Spare Conduit and Bend Requirements.......................................................19
5.4 Conduit Sizes................................................................................................... 19
5.5 Compliance to Australia Standard ...............................................................20
5.6 Colour of Conduit........................................................................................... 20
5.7 Conduit for Directional Boring ..................................................................... 21
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5.8 Design of Conduit Installation....................................................................... 21
5.9 Conduit Installation........................................................................................ 21
5.10 Sealing of Conduits......................................................................................... 22
6.0 TRENCHING ON PRIVATE PROPERTY ....................................... 23
7.0 TRENCHING FOR SINGLE CUSTOMER ON VERGE (OPTION)................................................................................................................. 24
8.0 EXCAVATION FOR VAULTS AND PIERS .................................... 24
9.0 BEDDING SAND .................................................................................. 25
10.0POLYMERIC CABLE COVERS / MARKER TAPE ...................... 25
11.0BACKFILLING AND CONSOLIDATION ....................................... 25
12.0CIVIL WORKS..................................................................................... 26
12.1 Applicants Responsibilities........................................................................... 26
13.0CIVIL WORKS 66KV UNDERGROUND CABLES..................... 27
13.1 Introduction .................................................................................................... 27
13.2 Design Information......................................................................................... 27
13.2.1 Extent of Civil Work ..........................................................................27
13.2.2 Cable Route Design Changes .............................................................28
13.3 Trench Dimensions......................................................................................... 28
13.4 Separation From Other Services...................................................................29
13.5 Directional Boring .......................................................................................... 29
13.6 Installation of Conduits in Open Trenches ..................................................29
13.7 Lubrication Points.......................................................................................... 30
13.8 Laying Cables.................................................................................................. 30
13.9 Thermocouples................................................................................................ 30
13.10Controlled Bedding in Cable Trenches ........................................................30
13.11Bentonite Mixture in Conduits...................................................................... 31
13.12Protective Cover Slabs ................................................................................... 31
13.13Backfilling........................................................................................................ 31
13.13.1 Sand Backfill .................................................................................... 31
13.14Cable Marker Tapes....................................................................................... 32
13.15Cable Markers ................................................................................................ 32
13.16Pits.................................................................................................................... 33
13.17Jointing of Bays............................................................................................... 33
14.0CONTAMINATED SOIL .................................................................... 33
15.0CIVIL WORKS COMPLIANCE........................................................ 33
15.1 Civil Works Notification ................................................................................ 34
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15.2 Civil Works Compliance................................................................................ 34
16.0FURTHER INFORMATION .............................................................. 34
17.0APPENDICIES..................................................................................... A1
APPENDIX A - CIVIL WORKS NOTIFICATION & COMPLIANCE
RESPONSIBILITY.............................................................................. A1
APPENDIX B CABLE LOCATION MARKING DRAWINGS .......... B1
APPENDIX B CABLE LOCATION MARKING DRAWINGS .......... B2
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1.0 DEFINITIONS
The term ETSA Utilities means:-
ETSA Utilities, ABN 13 332 330 749, a partnership of:
Spark Infrastructure SA (No. 1) Pty Ltd, ABN 54 091 142 380
Spark Infrastructure SA (No. 2) Pty Ltd, ABN 19 091 143 038Spark Infrastructure SA (No. 3) Pty Ltd, ABN 50 091 142 362
each incorporated in Australia
CKI Utilities Development Limited, ABN 65 090 718 880.
HEI Utilities Development Limited, ABN 82 090 718 951.
each incorporated in The Bahamas
1 Anzac Highway, Keswick, South Australia, 5035.
2.0 BACKGROUNDThe responsibility for the installation of a trench for the installation of ETSA
Utilities infrastructure can be:
The developer for land developments or a customer for network extensionsand alterations to the ETSA Utilities electrical network.
Council for Power Line Environment Committee (PLEC) projects.
ETSA Utilities for capital works and, under specific arrangements, somecustomer works.
ETSA Utilities may agree to provide a quotation for the installation of a trench on
behalf of a customer or a developer. For access to the list of Civil Contractors
utilised by ETSA Utilities refer to section 15.0.
This Technical Standard is based on the Electricity (General) Regulations 1997. For
any situation that is not covered by this Technical Standard, the requirements of
AS/NZS 3000-2000 shall apply.
Trenching needs to be undertaken in a workman-like manner and must meet the
requirements in TS 085 and any other relevant specification. A Civil Works
Compliance form is required prior to any Network connection. Refer to section
14.0 for further information.
Section 5.0 of the ETSA Utilities Terms and Conditions for External Contractor
Construction (refer to sect 15.0 for access) details the customer/developersobligations.
The trench is a critical and integral part of the electrical installation. ETSA Utilities
cables are covered in a soft layer of polyethylene which is very easily damaged.
A contractor should not work near any live electrical cables. Dial Before You Dig
should be contacted on telephone number1100 to verify the location of ETSA
Utilities and other infrastructure prior to the commencement of any civil works. An
access permit may be required if any electrical cables are in close proximity. A
contractor can contact the Network Access Officer on 84044119 for further
information.
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A contractor should not work in the area where there is electrical infrastructure, even
if the asset is de-energised without a high degree of due care as the cables can be
easily damaged.
To reduce the severity of damage to the outer sheath, all contractors who have
to work in the area of the electrical infrastructure MUST utilise a safe edge
(blunt nosed) shovel.
This style shovel minimises cable damage if a contractor inadvertently comes in
contact with a cable. Any damage to ETSA Utilities infrastructure will be at the cost
of the responsible party. If any party is aware of any damage to the electrical
infrastructure, ETSA Utilities or the electrical contractor undertaking an installation
should be notified at the earliest opportunity. Early notice may reduce future repair
costs.
The trench containing the electrical works is a component of the asset inspection
process and it is the responsibility of the developer/customer to ensure that the trench
meets the specification. An ETSA Utilities Asset Compliance Officer may inspect
the trench and any requirement for remedial work to a trench to ensure it satisfies
this Technical Standard and any associated specification will be at thedeveloper/customers cost.
If there are any queries on this Technical Standard (TS - 085) the Network Project
Officer responsible for your project should be contacted.
3.0 RETAINING WALLS
A transformer can weigh from 2.0 tonnes for a 150 kVA transformer up to 6.2 tonnes
for a 2000 kVA transformer. There may be a requirement to establish a retaining
wall to ensure the transformer has a stable footing and remains in a horizontal
orientation. The involvement of a Certified Engineer may be required to verify the
adequacy of any retaining wall installation. Council approval may also be required.
ETSA Utilities reserves the right to request engineering calculations for any
retaining wall.
A retaining wall for a Padmounted Transformer or a Switching Cubicle will normally
be installed in any location where there is a change in the ground level to
accommodate the Padmounted Transformer or Switching Cubicle in a suitable
horizontal orientation. Any cut or fill greater than 300mm in two metres within or
outside any extremity of the electrical equipment easement boundary will require a
retaining wall.
Any retaining wall above 1.0 metre in height will require engineering confirmationof the design and Council approval.
A Retaining wall must be completed prior to the installation of a padmounted
transformer and a switching cubicle.
The retaining wall should ideally be positioned at the extremity of the ETSA Utilities
easement and should not encroach into the area occupied by the transformer or
switching cubicle. The easement shall be of such a size that the retaining wall is
constructed entirely within the easement (see Figure 1). Where the wall is placed
beyond the standard easement, the easement must be extended to include the area
occupied by the retaining wall.
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Operating AreaRefer to TS-102
TRANSFORMERBoundary of PublicArea if appropriate.
Easement to beextended toinclude the areaoccupied by theretaining wall ifrequired.
Area for ETSAEquipment (onstandard
easement, Referto TS-102.
Figure 1 - RETAINING WALL
Retaining W all
OR
SWITCHING CUBICLE
In situations where a retaining wall is required for the retainment of fill material, the
easement boundary is to be extended by 1.0 metre to allow the retaining wall to be
constructed 1.0 metre inside the easement boundary. Refer to Figure 2.
The retaining wall and backfill must be designed to drain the area behind the wall
completely and to continue to do so indefinitely without blockage, so that hydrostatic
pressure is not exerted on the wall at any time.
Retaining walls shall be constructed of concrete masonry materials. If interlocking
style blocks are utilised, they must be of a pinned or socket and nib type. The two
top courses shall be pinned and glued with an epoxy style resin and the top course
shall consist of a glued top capping.
Open style interlocking blocks may be acceptable provided the soil is retained. The
use of Geo cloth type material may also be acceptable. To ensure the material to be
utilised for a retaining wall will be acceptable to ETSA Utilities, please contact your
ETSA Utilities Project Officer prior to installation. This style of retaining wall
construction has the potential to require an easement larger than standard.
ETSA Utilities will consider a submission from a certified engineer to a variation tothe construction material utilised for a retaining wall as described in this section.
Material to be retained shall be classified in one of the 3 types listed below:
Coarse grained soil without admixture of fine soil particles. Verypermeable (clean sand or gravel).
Coarse grained soil of low permeability due to admixture of particles of siltsize.
Residual soil with stones, fine silty sand and granular materials withconspicuous clay content.
Materials not acceptable include very soft or soft clay, organic silt or silty clays, andmedium or stiff clay.
Weep holes shall be provided in the retaining wall at the lowest points. An open
drain shall be provided to remove water from the area of the toe of the wall. A more
effective system of drainage consists of a continuous agricultural pipe located at the
base of all retaining walls and be surrounded by gravel or crushed stone with a
continuous vertical layer of granule material at least 300 mm thick covering the rear
face of the wall area.
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300mm
Ag pipe to exit at thefront of the retaining wall
Ground level
Continuous agriculturalpipe the length of allretaining wall sections.Agricultural pipe to drain tothe front of equipment.
Figure 3 - RETAINING WALL - CUT
Retaining Wall
With 100mm lipabove ground level
ETSATransformer/switching cubicle
Groundlevel
PreferredEasement
Weep hole
Ground level
Figure 2 - RETAINING WALL - FILL
Retainingwall
ETSA UtilitiesTransformer/switching cubicle
300mm min.
Granulated materialbehind all retaining
wall sections
Continuous agricultural pipethe length all retaining wallsections plus external weepholes on the lowest sectionof the retaining walls
NoteRetaining wall to bebuilt up to the heightof the base
Suitable retaining fillGround level
* 1.0m * ETSA Utilities extendedeasement requirement fora Fill situation.
Dispensation for the installation of a retaining wall can be granted by the relevant
regional Network Manager when the following can be verified;
The short and long term stability of the transformer will not be compromised.
The easement site and adjacent properties will not be impacted by erosion run off,
i.e. it can be demonstrated that the site adjacent to the easement is well consolidated
and /or there is other means of retainment or removal of any run off material.
4.0 TRENCHING
4.1 General
When conduits or cables are to be installed, the trench shall be as straight as
possible with a firm and smooth base.
The installation of multiple conduits requires a minimum separation of 25mm
in all directions between ETSA Utilities conduits and ETSA Utilities cables to
ensure the bedding sand fully encompasses the conduit at the time of back
filling. This will reduce future compaction issues.
There shall be a minimum separation of 50mm between direct laid ETSA
Utilities cable circuits. The greater the cable circuit separation, the greater the
current carrying capacity of the electrical cable. If the trench width is such thatthe minimum separation can be increased and the 50mm clearance to the trench
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wall is met, then the separation should be increased. From time to time there
may be a requirement for a specific separation that is greater then the
minimum.
Separation from a trench wall to any ETSA Utilities infrastructure will
normally be a minimum of 50mm. This is to reduce any damage to electrical
infrastructure from sharp edges, stones, etc. Under some circumstances ETSA
Utilities may approve a lesser dimension if it can be verified the trench edge is
such that it will not damage the installed cables or if the installed conduit is
medium or heavy duty.
Dimensions for ETSA Utilities infrastructure in this standard are the minimum
except where shown.
The maximum depth of any length of open trench should not be greater than
1.5 metres unless ETSA Utilities has approved a section of trench/ conduit
installation at a greater a depth. Any depth beyond this will be labelled an
excavation and may require shoring to be installed. Refer to the Occupational
Health, Safety & Welfare Regulations 1995.
The trench shall be located, when practicable, in accordance with the
publication A Code for the Placement of Infrastructure Services in New and
Existing Streets (Services in Streets Code) prepared by the Public Utilities
Advisory Committee (PUACC) and available from the Local Government
Association.
All variations to the Construction drawing must be noted by the installation
contractor and included on the As Constructed ETSA Utilities drawing.
4.2 Road Reserves and Road Crossings
The minimum cover under a carriageway shall be 750mm. A Department of
Transport, Energy and Infrastructure road has specific requirements and theseare detailed in section 4.3.
All cables under carriageways shall be installed in conduit. Any variation to
this must be under the direction of ETSA Utilities. Spare conduit installation
under a carriageway is to be as per section 5.2. and 5.4 of this standard.
For a primary cable network that is buried direct in the primary trench in a road
reserve such as a single customer network extension and a common service
trench for a development there is a requirement for spare conduits. Spare
conduits installed at a road crossing will need to match the spare conduits in
the primary trench. The road crossing conduits need to be continuous with the
primary trench spare conduits when practical.
Cables
50mm
Cable circuit separation
50mm minimum (refer 4.1)
25mm
25mm
Bottom of trench
Conduit
Bedding Sand
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These conduits will be in addition to the conduits at a road crossing that will be
utilised for a direct buried cable installation.
A road crossing for a low voltage tee off (such as a common service trench)
that is not part of a continuous run of cable only requires a conduit for a cable
(no spare).
Conduits installed at a road crossing that are for a direct buried cableinstallation shall extend the full width of the carriageway and extend 900mm
into the footpath verge from the back of kerb.
The electrical designer and contractor responsible for conduit installation at
road crossings should ensure that the appropriate number of conduits are
installed. Any road crossing excavation for continuous conduits needs to
consider the cover and trench floor invert of the conduits that are to be installed
in the road verge.
4.3 Requirements for Department of Transport, Energy and InfrastructureRoads
Department of Transport, Energy and Infrastructure (DTEI) have very specific
requirements for any work being undertaken on a DTEI controlled road. The
requirements include both excavation and traffic management and apply to
overhead and underground works.
The DTEI specification for the Excavation and Reinstatement of Road
Pavement is available from DTEI on (tel 8226 8222). ETSA Utilities
recommends that any contractor involved with the installation of either
underground or overhead electrical works on a DTEI road obtain the latest
DTEI Standard Specification and be fully conversant with all of the
requirements.
Roadside Significant Sites of an environmental or cultural significance must be
considered by both the designer and the contractor. In country regions DTEI
have highlighted most DTEI controlled roadside sites with a distinctive but
discreet marker.
Information and a list of Roadside Significant sites is available from the Land
Development Account Manager at Keswick on 8404 5439.
Some of the relevant sections of the specification dated February 2003 are
detailed below.
4.3.1 Open Trenching
Most trenching involves work on medium or heavily trafficked roads
with an asphalt surface. There is a requirement that all services must be
at a minimum depth of 1 metre cover. Any trenching involving an
ETSA Utilities installation and other authorities may require a wider
trench to ensure that appropriate separations are achieved without
shoring requirements.
Reinstatement needs to be as per the DTEI standard specification.
Excavated material can not normally be reused.
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4.3.2 Trenchless Method
Multiple conduits can be passed through a single bore or tunnel. It is
required that there is a minimum spacing of 10D between single bores
when there are multiple bores. D is the diameter of the largest conduit.
The minimum depth of a trenchless bore will generally be 1.5 metres
to minimise ground swell. The final depth is to be determined inconjunction with the boring contractor, with the minimum depth to be
achieved wherever possible.
4.3.3 Department of Transport, Energy and Infrastructure Notification
The electrical designer should submit any design to DTEI for comment
where any ETSA Utilities infrastructure, ie, poles, cable or conduit, will
be running parallel to the kerb for some distance. This is to ensure any
installation takes into account any future road widening.
The Constructor
An electrical or civil contractor will need to submit a Notification of
Works Impacting SA Roads form NICC-251 (refer to sect 15.0 for
access) 5 working days prior to the commencement of works. Any civil
works that will be undertaken on a DTEI road over a period greater
than one day requires 4 weeks notice.
The notice is required for the following:
Any work that requires traffic management. This includes workon overhead mains
An open trench and trenchless boring
Any cable pulling through installed conduits.
4.3.4 Traffic Control Notification
The Metropolitan Traffic Control Centre - telephone 1800 018 313,
must be notified of any ETSA Utilities and civil works that require
DTEI approval (refer 4.3.3). The centre needs notification 15 minutes
prior to work commencing and 15 minutes after the road has reopened.
4.3.5 Installation Details
There is requirement that DTEI receives within 3 days of the
completion of works a log of any excavation with the construction date,
location and depths and details of the reinstatement.
Minimum
1.5 metres
Ground level
10 X 125mm =
1.25m minimum100mm conduit
125mm conduit
Bore 1 Bore 2
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ETSA Utilities also requires a copy of the installation details and who
undertook the civil works with the Civil Works Compliance form.
The form is a part the electrical works compliance and connection
process.
4.3.6 Emergency Work
DTEI requires verbal notification to the appropriate DTEIrepresentative at the earliest opportunity. This must be followed with
the submission of the Notification of Works Impacting SA Roads
form within 24 hours of the emergency.
4.3.7 Maintenance Period
The contractor undertaking the civil component of the electrical works
associated with the DTEI road crossing will be responsible for the cost
of making good any settlement or other deterioration in the reinstated
excavation for the maintenance period which is one year.
4.4 Installation of Conduits Within Railway Boundaries
Australian Standard AS4799 2000 Installation of underground utility
services and pipelines within railway boundaries covers the requirements for
both the design and installation of electrical infrastructure within a railway
property.
There is specific design information and approvals that are needed for right of
entry as well as easement agreements.
The form Application to Cross Railways With Electric Power Cables NICC-
252 (refer to sect 15.0 for access) must be filled out by the designer a minimum
of28 working days prior to any work taking place and forwarded to;
ETSA Utilities Easements Coordinator:
level 6, 1 Anzac Highway Keswick 5035
Telephone 84045897 fax 84045193
You will need to supply a preliminary design drawing or a section of DCDB
with street names, rail lines and the crossing point marked.
There are a number of authorities that ETSA Utilities may require approval
from.
Australian Rail and Track Corporation
Australian Southern railroad
Trans Adelaide
Department of Transport, Energy and Infrastructure
Confirmation that any conduit to be installed satisfies the design load for the
railway loading may be required. Confirmation from the railway authority that
the electrical design has approval will be required prior to ETSA Utilities
issuing a Specification Compliance.
An electrical conduit should be a minimum of 2metres deep under any rail line
and for a 3metre distance beyond the outer rails. Conduits in other locations ina railway property must have 1 metre minimum cover. A railway authority
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may approve a lesser depth, but the depth must not be less then the ETSA
Utilities standard.
4.5 Clearances between Services
Vertical Separation
These dimensions are relevant where external parties pipes cross over or
under ETSA Utilities plant.ETSA Utilities
LV Mains
ETSA Utilities
HV Mains
Comms
plant pipe100 300
Comms
plant pits100 100
Gas pipes 200 200
SA Water
Sewer
225 for
sewer main
300
Other sewermains 300
225 for
sewer main
300
Other sewermains 300
SA Water
Water225 225
Private
Sewer600 1 600 1
Private
Water600 600
All clearances are in millimetres.
Comms = Telecommunications
1 Unless agreed to by ETSA Utilities the default clearance is 600mm. A lesser
dimension of 150mm for sewer pipe and 100mm for a water main < DN65 or
300mm for a water main > DN65 can be utilised where it can be verified that
there is orange marker tape and mechanical protection (concrete slabs or
continuous concrete pour) for ETSA Utilities plant at any point of exposure.
Notes:
1) These are minimum separations. For any other authority a minimumseparation of 150mm is required. Greater separation may be requested in
the ETSA Utilities specification from time to time.
2) To achieve these clearances it may be necessary to increase the cover onETSA Utilities cables and/or conduit or increase the trench width.
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Horizontal Separation
Horizontal separation will be dependant on the extent that the external plant is
parallel with the ETSA infrastructure. To ensure compliance with the
Electricity Act there is ONLY hand digging permissible by an external party
for any excavation within 1000mm of any ETSA Utilities plant. To ensure
future access for mechanical plant a minimum of 1000mm separation is
required and should be considered.
ETSA Utilities
LV Mains
ETSA Utilities
HV Mains
Comms
plant pipe100 300
Comms
plant pits100 100
Gas pipes 200 200
SA Water
Sewer
500 for
sewer main
300
Other sewermains 1000
500 for
sewer main
300
Other sewermains 1000
SA Water
Water
500 for
water main
200
Other water
mains 1000
500 for
water main
200
Other water
mains 1000
Private
Sewer600 600
Private
Water600 600
All clearances are in millimetres.
Comms = Telecommunications
4.6 Changes in levels and directional changes
The depth of any conduit installation in the carriageway should match that of
any conduit installation on the road verge (footpath). If this is not achievable
the cover at the end of a conduit at a road crossing should be at the same level
as the conduit in the verge. Conduit bends may need to be installed to achieve
this.
Straight lengths of the standard 100mm very light duty / class 4.5 conduit can
be subjected to a minor degree of bending (approximately 10 - 15 degrees over
the length of the conduit). Any deviation greater then 15 degrees will require
the installation of appropriate bends.
Conduit is not to be installed with a kink in its length under any circumstances.
Any section that is damaged will need to be repaired prior to ETSA Utilities
accepting the asset.
Any major variation to the depth of a conduit will have an impact on the ease
the electrical installer will have installing a cable in a conduit. A gradient rise
or fall should be limited to 100mm per metre for the primary run of ETSA
Utilities cables and conduits. Appropriate bends with the smallest radius
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requirement to achieve a satisfactory clearance to other of services should be
utilised.
Retrospective undergrounding projects will provide challenges to the civil
contractor from time to time when other service providers infrastructure is
encountered within the trench. It will be the civil contractors responsibility to
resolve these issues and the assistance of the Project Officer should be sought
to ensure that a resolution is agreed on that is to the satisfaction of ETSA
Utilitiesprior to construction.
Below are some examples of conflict and possible solutions
Preferredgradient rise/fall
of conduit100mm per
1metre
ETSAconduit
NoteIf Y > 1.5m it may bepreferreble to goover service.
150mmminimumunder service.
G.L.
X Sharp bends
X Couplinglocation is notappropriate if there isany tension. Thiscreates a lip whichcan damage cables
`Y
INCORRECT PREFERRED
G.L.
Alternative
Conduitroute
The example shows an in-appropriate conduit coupling with excess tension
applied to both the coupling and a straight length of conduit.
It is important that the developer and electrical contractor establish appropriate
ground levels at the time of the installation of the electrical works to ensure
that there is no requirement to alter ground levels by a third party after
installation. Under the Electricity Act 1996 and Electricity (General)
Regulations 1997 the SA Independent Regulator can impose a fine for any
breach.
Refer to Part 6, Clause 38 of the Electricity (General) Regulations 1997.
4.7 Common Service Trench
A Common Service Trench is normally installed as part of a greenfield housing
project. The trench is the responsibility of the Developer and contains
electrical and other infrastructure providers.
A trench will normally be 600 mm wide but could be up to 1200 mm wide
depending on soil type and footpath location. In consultation with the
electrical contractor, a width of 450 mm may be acceptable for single cable
runs. The design drawings should specify any non-typical width.
Reference should be made to the Services in Streets Code for any trench
location in a road reserve.
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The depth of the trench shall be such as to achieve a minimum cover of 750
mm above conduits and 1000 mm above all direct buried cables to finished
ground level. A typical cross section of trench occupied by the underground
mains, Telstra and Gas is shown below:
Typical
width
(Refer to Services
in Streets Code)
50mm
GAS
TELSTRA
750 mm
450mm
600mm
FOOTPATH
BEDDINGSAND
Property
line
1600mm 600 mm
COMMON SERVICE TRENCH
main SideKERB
LV HV P/L
50mm
1000 mm
Spare conduit
Cables buried direct
Top of
bedding sand
Notes
Refer to
section 4.1
50mm
Typical width
50mm
GAS
TELSTRA750 mm
minm at the
finished
road service
level at thekerb invert
For a TSA
road refer to
sect 4.3
450mm
600mm
BEDDING SAND
600 mm
COMMONSERVICE TRENCH - Road Crossing (non TSA road)
Note
Cover slabs or warning tape is
to be placed 75 mm above
ETSA plant if ETSA istheonly occupant of the road
crossing
SPARE CONDUIT
Notes
Refer to
section 4.1
LV HV P/L
road level
4.8 Trenching for Restrospective Undergrounding (eg PLEC schemes)
Trench dimensions shall be sufficient to satisfy the minimum dimensions and
clearances ETSA Utilities specifies in this Standard or as specified in theETSA Utilities specification. The designer will need to also consider for each
installation the available space and proximity to other services as well as DTEI
design and operational requirements.
The preferred method of trenching in an existing road reserve which is located
in a busy footpath and vehicular traffic area is to install a fully conduited
system at the appropriate depth and back fill on completion of specific
sections. A draw wire should be installed for any proposed cable installations.
This method of installation minimises disruption to footpath and vehicular
traffic and business premises.
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Additional conduit
Refer to 5.2.
50mm
750 mm
Bedding sand
Kerb
LV HV P/L 50mm
Warning tape
Property line Footpath
RETROSPECTIVE UNDERGROUNDING (PLEC)
ETSA ONLY TRENCH
200mm
maxm
Notes
Refer to
section 4.1
450 mm
Additional conduit
Refer 5.250mm
Gas, when applicable
Telstra, when applicable
750mm
600mm
Kerb
LV HV P/L 50mm
Warning
tape
200mm
maxm
Property lineFootpath
RETROSPECTIVE UNDERGROUNDING (PLEC)
COMMON SERVICE TRENCH
Bedding sandNotes
Refer to
section 4.1
4.8.1 Pit Installations
There are a number of pits of increasing size that are available and the
pit that is to be installed needs to be appropriate for the purpose. The
designer also needs to be mind-full of other services, refer to TS-100
and specific E-drawings.
When conduits are installed into the body of a pit, the conduit needs to
be 25 50mm inside the body. All conduit edges are to have no sharp
edges. All conduit entries are to be capped by the contractor to stop theentry of foreign material between the time of the conduit installation
and the installation of ETSA Utilities cables. Refer to section 5.10.
Expanding foam or silicon should be utilised as a sealer at the conduit
entry point into the wall of a service pillar if the conduit is not a tight
fit.
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Note1 Refer to E1921 sht 2.1
for standard arrangements2 Refer to E1921 sht 6.1 to 6.4
for assembly details3 A P5 pit is preferred for LV
cable junctions and servicearrangements for approvedbelow ground connections
Conduit to finish25mm - 50mm inside pit
CABLE & CONDUIT ENTRY INTO JUNCTION PITS
Extended P5 pit(1 Standard body plus oneshortened body or collar)at preferred 985mm invert
Preferred 0 40mm to pitbottom for low voltagecable entry to ensureappropriate room forcable cones
4.9 Location Marking of LV & HV Cable Trenches
Wherever cables are laid in underground trenches in rural locations or across
private property then cable location markers are to be installed to clearly
identify the location of the underground cables. The cable location marker,
KS3720 is also to be installed to locate service pits/pillars in both rural and
residential land developments where the development is likely to remain
unoccupied for an extended period of time and where the natural vegetationwill prevent the obvious identification of the ETSA Utilities equipment. Refer
to Appendix B for specific details of ETSA Utilities required cable location
marking systems.
4.10 Trenchless/Directional Boring
There can be economies in some trenching scenarios to undertake the
installation of conduit by the trenchless boring technique. If this system is
utilised the minimum depth needs to be 1.5metres to ensure there is no
groundswell above the conduit installation.
Any trenchless bore installation requires a bore log of the final depths and
locations to be included on the As Constructed drawing as a permanent
record of the installation.
5.0 CONDUIT REQUIREMENTS
5.1 General
Cables shall be installed in conduits in the following circumstances:
Road crossings
Full length of pathways with restricted access ie, a pathway between fencedallotments)
Cables installed through easements. Public lighting cables which are installed in independent trench to
AS/NZS3000 and CLER Tariff lighting installations.
Retrospective undergrounding (i.e. PLEC Projects)
On private property where cables vest in ETSA Utilities (Refer to section6.0 for all options)
Earth cables do not need to be installed in conduits.
Where there will be access roads, driveways and footpath crossings greater
then 2.5 metres in width, conduits for a cable installation as well as spare
conduit requirements may need to be included in a design.
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Full details of the conduits must be included on a design drawing and the As
Constructed drawing must reflect the actual installation. Any breaks in a
continuous conduit installation must be noted as must any changes in the as
installed conduit size.
Only straight lengths of conduits shall be installed in a straight line open trench
installation. Coiled conduit, i.e. coiled directional boring conduit, can not be
utilised.
11kV cables must not be installed in the same conduit as low voltage
cables
5.2 Spare Conduit Provision
Spare conduits are required to be included in the design and installed for the
following;
5.2.1 Wherever an electrical cable is buried direct, ie in a road reserve
The conduit installation needs to be such that any buried direct cable
can be reinstated in a spare conduit.
As an example;
There are three circuits of low voltage and one circuit of 300mm2 high
voltage cable being buried direct in a common service trench. In
accordance with section 5.4 Conduit Sizes the cables require the
following;
For the Low voltage: 3 x 100mm VLD conduit
For the high voltage: 3 x 100mm VLD conduit
Note: Where one LV circuit consists of two or more parallel bundles ofcables, a spare conduit must be provided for each bundle of cables.
5.2.2 When a cable is installed in a conduit
To ensure future access to ETSA Utilities infrastructure is kept to a
minimum there is a requirement where cables are to be installed in
conduit for additional conduits.
Unless specified differently in the ETSA Utilities specification the
requirement is:
A PLEC Project One spare conduit foreach of the low voltage
circuits. 2 x 150 mm2
parallel cables is deemed tobe one circuit.
One spare conduit foreach of the high voltage
circuits up to and including 95mm2.
One spare conduit per phase for any 300mm2 and
630mm2 high voltage installation.
This is the maximum conduit installation as per the
PLEC Guidelines. The PLEC group will advise a
designer of the conduits to be installed after
consideration of space availability and future growth
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requirements. The minimum requirement is as per a
customer project.
A Customer Project - ( ie, through any easement)
For every 3 conduits (or part there of) installed
that are to be occupied by cables, there is one
additional conduit included in the installation.As an example,
There are 3 cable circuits installed in conduits
made up of 2 low voltage circuits in 2 x 100mm
conduits and one 300mm2 high voltage cable
with one phase installed in a each of 3 x 100mm
conduits.
Note: Any public lighting cable installed in a
medium or heavy duty conduit is excluded from
the requirements of 5.2.2.
There are a total of 5 conduits with cables.
With a requirement of one spare conduit per 3
occupied conduits, or part thereof, there will
need to be 2 additional conduits included in the
installation.
5.2.3 Road Crossings
There is a requirement for spare conduits as well as the conduits that
are to be utilised at the time of the cable installation at road crossings.
Refer to section 4.2 of this standard for details.
5.3 Spare Conduit and Bend Requirements
Where spare conduits are required (refer to section 5.0), the extent of the
installation should satisfy the following table:
Situation Requirement
Common trench T intersections no bend requirement
Transformer vaults - general no bend requirement
Transformer vault for a future stage bends required
Trench direction changes greater than 90 deg no bend requirement
Trench direction changes less than 90 deg Bends required
Road crossing - primary cable run ContinuousRoad crossing tee off/non continuous nil
The requirement for bends will need to be assessed at the time of installation as
well as at the time of trench design layout.
5.4 Conduit Sizes
While the chart specifies minimum conduit sizes, a larger conduit may be
installed on the proviso that the conduit can be made continuous with any
existing or future continuous conduit installation.
A conduit of a higher classification can be utilised then those specified.
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The minimum size of a conduit for a specific cable size are as follows:
Cable Circuit Conduit Size Conduit Bend
LV Main & Service
bundled
1 x 100mm VLD 1800 radius, Light duty
HV 35mm2 1 x 100mm VLD 1800 radius, Light duty
HV 95mm2 1 x 100mm VLD 1800 radius, Light dutyHV 300mm2 and
630mm2
3 x 100mm VLD 1800 radius, Light duty
Public Lighting 1 x 32mm HD 312 radius, Heavy duty
CBD installation No x 125mm VLD
66kV Projects 1 x 200mm per
cable HD
Greater than min. bending
radius of cable, HD
The ETSA Utilities standard class 4.5 is equivalent to very light duty
(VLD*)
The ETSA Utilities standard class 6.0 is equivalent to light duty (LD)
The ETSA Utilities standard class 12 is equivalent to heavy duty (HD)
* ETSA Utilities considers that 100mm (NC1567) Sandwich construction
rigid VLD PVC conduit by Iplex to be suitable for installation as VLD conduit.
For installation and handling requirements see notes in clause 5.5 below.
Care must be taken in joining conduits. Different grades have different internal
diameters and the resultant raised internal edge has the potential to damage the
outer layer of cable during cable pulling.
5.5 Compliance to Australia Standard
Conduits and couplings shall be uPVC material and meet the requirements of
AS/NZS 2053 Parts 1 and 2 for Rigid Plain designation. The conduit will be
marked with the word electrical, the conduit size and class, egELECTRICAL DUCTING 100 mm 4.5 class. No other form of rigid conduit
is permitted without the approval of the Network Standards Manager.
Conduits shall also meet the requirements of AS/NZS 1477 - 1996 for the Test
for Impact at 20 degrees C.
NOTE
ETSA Utilities requires that the installation and handling of Sandwich
construction rigid VLD PVC conduit be in accordance with:
Iplexs reference of James Hardie Pipelines Manual Jointing Methods
SWJ which details the cutting & jointing of uPVC pressure pipes &fittings.
PIPA (Plastics Industry Pipe Association of Aust Ltd) website which hasIndustry Guidelines for Solvent Cement Jointing of PVC-U Pipe Issue 1.0
ref.PVC002 dated 2 Mar 06 which gives similar jointing procedures to
those in JHs manual but notes cut using a fine toothed saw or
abrasive disc.
AS/NZS 2032:2006 Clause 5.3.11 Bending of PVC Pipes whichrecommends a minimum radius of 150 x OD for non pressure (electrical)
pipes.
5.6 Colour of Conduit
Conduits and couplings shall be light orange in colour.
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5.7 Conduit for Directional Boring
The conduit used for directional boring must :
a) meet our minimum requirements and AS/NZS4130.
b) be able to withstand the forces involved in the directional boring process.
c) be light orange in colour. Black conduit with orange stripes may beutilised with the approval of the project officer if orange conduit is not
available.
d) be of size and characteristics to allow the cable to achieve its currentrating.
e) Be anchored at conduit entry/exit appropriately to maintain its horizontal
profile. The polyethelyne material has a memory and will attempt to coil
up. This will introduce stress at conduit transition locations and at the
start/end of a directional boring conduit installation.
5.8 Design of Conduit Installation
Conduit designs shall be prepared to ensure that pulling tensions do not exceed
the maximum permissible as required by the Construction Standard TS 087.
Installation details and techniques for cable pulling through conduits are in
E1906. Lube points need to be considered by the designer for long pulls with
multiple bends.
Reference to an indication of cable pulling tensions is listed in E1910 sheet 4.2
5.9 Conduit Installation
Conduits shall be laid on an evenly bedded 50mm thick layer of well-graded
sand substantially free from lumps and particles having a dimension in excess
of 6mm. After the laying of each length, bedding material shall be placed and
tamped to hold the conduit securely in position and provide a cover of 50mm
when compacted.
A minimum of one hour should be allowed between any conduit gluing and the
installation a draw rope. The gluing of conduits should be carried out to the
manufacturers recommendations.
Floor of trench /opening for bore
Edge ofentry/exit
hole
Securing the end of directional boring conduit
Directional boring
conduit
End of polyethylene
pipe to be concrete
encased or
sandbagged
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Draw rope with a 6mm minimum diameter and made from a material approved
by ETSA Utilities may be required for some projects.
The exposed ends of all conduits shall be cleanly and squarely cut and fitted
with PVC caps to prevent the entry of water, dirt or other foreign matter.
For spare conduits in a group, the position of the ends shall not vary by more
than 300mm. Where conduits are installed in layers, the ends shall bepositioned horizontally.
Conduits between new and existing subdivisions must be joined together.
Cable markers are required wherever ETSA Utilities conduits/cables pass
through private property. Refer to Appendix B for installation details.
5.10 Sealing of Conduits
For a cable Installation
Where cables have been installed in conduits, a conduit end shall be adequately
sealed to prevent the entrance of dirt, stones, white ants and moisture into the
conduit by the use of polyurethane expanded foam applied in accordance withthe manufacturer's instructions.
The expanding foam should not encroach into the conduit any further then
75mm. This will ensure that the foam/cable can be easily removed if the need
arises.
Sealing of conduits with cables
For conduits with no cables
The use of end caps is a requirement for any conduit that is to remain vacant.
This includes the installation of end caps on a temporary basis on a conduit that
will not have a cable installed immediately.
Description Stock Item No
Cap, push on 40mm for consumers conduit
Cap, push on 50mm for consumers conduit NC 6462
Cap, push on 100mm NC 6501
Scrunched plastic or
newspaper
Cable
Approx 75mm
Expanding foam
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6.0 TRENCHING ON PRIVATE PROPERTY
Trench dimensions shall be sufficient to satisfy the minimum ETSA Utilities
requirements as specified in this Technical Standard and an ETSA Utilities
specification.
There are three options for cable installation:
Diagram A Install all cables in conduits buried at a depth of 1000 mm as
shown. The polymeric cover slabs are not required but may be
installed if desired.
Diagram B Install cables in conduit at a depth of 750mm. Install polymeric
cover slabs (if required) and warning tape as shown. Conduit
requirements are as per section 5.0.
Diagram C Install cables buried direct at a depth of 1000 mm. Spare conduits
as section 5 are required for the cable circuits that are to be
installed. Polymeric cover slabs are still to be installed.
Warning tape is required in all cases.
50mm
BEDDING
SANDPL LV Spare HV
200 mm
maxm
WARNING
TAPE
50mm
1000mm
50mm
750 mm
minm.
BEDDING
SAND
P/L LV Spare HV
POLYMERIC
COVER SLAB
50mm
75mm
maxm
Diagram A cable in conduit at 1000 mm Diagram B Cable in conduit at 750mm
750 mm
minm
50mmBEDDING
SANDP/L LV HV
POLYMERIC
COVER SLAB
5mm thick
50mm
Spare conduits
75mmmaxm
C
dDiagram C
Cable buried direct
Notes
Refer to section 4.1
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7.0 TRENCHING FOR SINGLE CUSTOMER ON VERGE (OPTION)
Trench dimensions shall be determined as required by ETSA Utilities and the
customer, and will depend on the available space and proximity to other services.
Where the cables are to be direct buried, the trench configuration shall be in
accordance with the following diagram.
750mm
200mm
maxm
Spare conduit
Cables buried direct
Public lighting can be
in conduit or buried
direct
50mm
1000 mm
WARNING TAPE
BEDDING SAND
50mm
Notes
Refer section 4.1
ROAD VERGE -
SINGLE CUSTOMER
Any ETSA Utilities cable system that needs to be located under a road needs tosatisfy either the requirements detailed in section 4.5. for common service trenches or
section 4.3 if it is a Department of Transport, Energy and Infrastructure road.
In situations where public lighting circuits within conduits are to be located in a
trench alone, (eg no adjacent power circuits or spare conduits), the minimum cover
shall be 500mm with warning tape installed at 250mm. In these situations the cable
installation is required to comply with the requirements of AS/NZS 3000.
Any public lighting network that is a Customer Lantern Energy Rate (CLER) or is
fed from a metered supply point requires a minimum separation of 150mm from any
ETSA Utilities infrastructure.
8.0 EXCAVATION FOR VAULTS AND PIERS
The excavation for vaults and piers shall be as follows:
(a) Padmount Transformer Vaults:
the dimensions are in the order of 1850 long x 1000 wide x 1250 deep,
totalling approximately 2.5 m of spoil to be excavated.
(b) Padmount Transformer Piers:
Must be bored as per E1982 Sheets 2 & 3.
(c) Switching Cubicle Vaults:
the dimensions are in the order of 2250 long x 1000 wide x 1175 deep,
totalling approximately 2.7 m of spoil to be excavated.
The spoil requiring excavation for the above two cases allows working room for the
placement of cables in conjunction with installation of the vaults.
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9.0 BEDDING SAND
Bedding sand must be:
(a) used prior to and after the laying of cables.
(b) layed below and above the cable and conduits to the depths shown in section 3
of this standard.
(c) used under any cable vault and service pit installation.
(d) lightly and evenly compacted by tamping with feet or by rolling the trench bed
prior to backfilling. Minimum coverage requirements must be maintained.
(e) in compliance with the ETSA Utilities specification.
Some common sand types are designated as DS4B and PM64. The specification for
these types differs from the ETSA Utilities standard. It is the contractors
responsibility to ensure the installed sand meets the ETSA Utilities specification.
See table below for specification details.
TEST METHOD TEST PERMITTED
TEST VALUES
Grading Percent Passing
AS1141.11-1996 Sieve Sizes mm
AS1152-1993 4.75 100
2.36 98 - 100
1.18 94 - 100
0.6 85 - 100
0.425 55 - 1000.3 25 - 100
0.15 5 - 40
0.075 0 - 10
AS1289.3.3.1-1995 Plasticity Index Maximum 6
(non plastic)
10.0POLYMERIC CABLE COVERS / MARKER TAPE
The stock item for the 5mm polymeric cable cover is RN 0202 which is supplied as a
15 metre long roll, 300mm wide. To satisfy AS/NZS 3000 the strip must be placed
no more than 75mm above ETSA Utilities infrastructure and must overlap the ETSA
Utilities infrastructure by 40mm per side.
Marker tape is a requirement for PLEC projects. For any other installation, if the
conduits installed for electrical infrastructure are not a light orange in colour, marker
tape will be required to be installed not more then 200mm above the conduits. If
polymeric cable covers have been installed marker tape is not a requirement.
11.0BACKFILLING AND CONSOLIDATION
The backfilling of trenches, tunnels, joint bays and any other associated excavations
must be carried out by the Contractor as soon as practicable after cable/conduitlaying and/or jointing is completed.
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Before backfilling operations of any trench excavation commence, surplus jointing
materials, any waste materials and all rubbish including timber and foreign material
will be removed from the trench.
Backfill material shall not be placed in any excavation containing free water or
slurry.
Backfilling material must be clean and completely free from all fibrous andvegetable matter and other material which may attract or be attacked by termites.
Excavated material from the trench may be used as backfill above the bedding sand
provided that this material is predominantly soil. If the material does contain any
metal or rocks, then it may only be used if:
the amount of metal and rocks is less than 20% of the material (by volume)
the metal and rocks pass through a 50 mm screen.
Where cables and/or conduits are laid beneath other buried services, the Contractor
shall ensure that the backfill beneath such services is adequately compacted such
that:(a) no voids between cables and/or conduit layers detrimental to the cable rating
occurs, and
(b) damage to the other buried services, due to inadequate support, is prevented.
Consolidation of the backfilled excavations will be in accordance with the local
Council or Department of Transport, Energy and Infrastructure specifications as
appropriate.
12.0CIVIL WORKS
12.1 Applicants ResponsibilitiesThe Applicant or an agent of the applicant shall be responsible for:
Ensuring that all allotment pegs, including any replacement pegs,easement pegs and level pegs are correctly placed, clearly visible, and
numbered to show allotment numbers, reserves, easements etc.
Carrying out and co-ordinating all the pegging, trenching, backfilling,reinstatement, levelling, and associated work including retaining walls,
necessary for the installation of cables, transformers and switching
stations, service pits and pillars and lighting columns.
The safety of the open trench and any liability arising from theApplicant's works. This includes ensuring that there is suitable clearance
between any excavation and existing ETSA Utilities infrastructure,
including poles and footings. A financial penalty can be applied by the
industry Regulator for any unlawful interference.
All street and ground openings and all costs including the compactionand reinstatement of road and footpath surfaces and services where
disturbed or damaged, to the satisfaction of the authority or owner
concerned.
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Arrangements with the local authorities and public service utilities forthe temporary disturbance of any driveway, culvert, pipe, drain, kerb,
survey mark etc.
Excavations of padmount transformer vaults and footings and switchingcubicle vaults and footings and the reinstatement of the remaining
excavation surrounding vaults.
Damage caused to vaults and associated equipment during backfillingand compaction.
13.0CIVIL WORKS 66kV UNDERGROUND CABLES
13.1 Introduction
This section of the Technical Standard sets out the essential design
requirements for the civil works associated with the installation of 66kV
underground cables. These requirements are in addition to all other
requirements of this Technical Standard.
13.2 Design Information
ETSA Utilities will supply specification information relating to the cable
project. The information to be provided will include the following;
cable route drawing
conduit requirements
directional boring requirements
cored pole footing requirements
thermocouple location requirements
conduit arrangement
conduit depth
type of bonding
Bentonite requirement
13.2.1 Extent of Civil Work
The work involves the complete installation of the cables in accordance
with this standard including:
(a) Verification of route
(b) Excavation
(c) Installation of conduits
(d) Laying cables
(e) Backfilling
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13.2.2 Cable Route Design Changes
Any changes to the cable alignment, cable depth or to the location of
joints, recommended by the Contractor, shall be submitted to ETSA
Utilities for approval prior to commencing installation of the cable.
13.3 Trench Dimensions
Trenches shall be excavated to the dimensions shown on the typical drawingssubmitted with the Contractor's tender and approved by ETSA Utilities and
shall provide a minimum as specified by the cable specification. The cable
spacing and depth are project dependent to maximise cable rating.
The drawings shall show cross-sections of trenches including the cables and
cover slabs, size and spacing of ducts including concrete surrounds, all in their
correct position and fully dimensioned. These dimensions shall constitute
"Standard Trenches" within the terms of the contract and shall be used for the
determination of contract price adjustments on account of variations in trench
dimension as may be required by ETSA Utilities.
100mm
Note Cover slabs are to be placed
100mm above ETSA plant
Marker Tape with Trace Wire
Communications and Earth
wire (project dependant)
200mm
100mm
x x
BEDDING SAND
100mm
Cable / Conduit spacing is project specific
(min 100mm from conduit to edge of trench)
As specified
in cable
specification
Flat Arrangement 66kV Cables
Surface level
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100mm
Note Cover slabs are to be placed
100mm above ETSA plant
BEDDING SAND
Marker Tape with Trace Wire
Communications and Earth
wire (project dependant)
200mm
Trefoil Arrangement 66kV Cables
100mm
As specified
in cable
specification
Surface level
Width is project specific
(min 100mm from conduit to edge of trench)
13.4 Separation From Other Services
No other services are to be laid in parallel with the 66kV cable within 1 metre.
All services crossing the 66kV cables have to be approved by ETSA Utilities.
Clearances between services and changes to levels and directional changes
shall comply with the respective clauses in this Technical Standard.
13.5 Directional Boring
The trenchless method of conduit installation involves directional boring. Refer
to clause 4.3.2 and 4.10 of this Technical Standard.Separate conduits shall be used for each single-core cable. The conduits shall
be non-metallic. The conduits shall be either in a flat or trefoil arrangement.
All trenchless bore installations require a bore log of the final depths and refer
to clause 5.7 for conduit requirements when directional boring.
13.6 Installation of Conduits in Open Trenches
The Contractor shall install conduits for the cables at locations as specified,
and as shown on the cable route drawings.
Separate conduits shall be used for each single-core cable. The conduits shall
be non-metallic and shall be bedded in controlled bedding material. Theseconduits shall be parallel and spaced evenly (flat arrangement) or shall be in a
trefoil arrangement.
At locations other than specified in the cable route drawings, consideration will
be given to any proposal to install the cables in ducts to simplify the cable
installation provided the cable system will remain adequate to meet the service
conditions specified. ETSA Utilities approval is required for such variations.
Conduits may need to be filled with Bentonite mixture to ensure that the sand
thermal resistivity requirements are met.
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13.7 Lubrication Points
Lube Injection Points (LIPs) are to be installed according to the designers/
ETSA Utilities requirements. ETSA Utilities will nominate the exact number
and location of LIPs prior to commencement of conduit installation. Generally
they are positioned before bends and over long lengths where heavy cable
hauling is expected. For details on construction of LIPs refer to ETSA Utilities
E drawing E1906 Sheet 3.
13.8 Laying Cables
The cables shall be pulled into the trench or conduits in a manner to be
approved by ETSA Utilities. The contractor shall present calculations for the
cable pull tensions to the DaNM Project Manager at least 3 weeks before the
proposed pulling of cables. ETSA Utilities and the cable manufacturer have to
approve these calculations.
After any cable has been laid, and until the whole of the cables to be laid in the
trench have been covered with their protective cover slabs, no sharp metal
tools such as spades or crowbars shall be used in the trenches or placed in sucha position that they can fall into the trench.
The Contractor shall give notice of the completion of laying each length of
cable and shall not commence to backfill the trench until notified by ETSA
Utilities that he has recorded the length and position of the cable with respect
to the various datums and other underground services and obstructions.
Records shall be kept by the Contractor for each section of cable, stating its
location, the drum number, direction of pull and other relevant information.
13.9 Thermocouples
Thermocouples, where specified, shall be fitted to the outer serving of thepower cables in accordance with the cable manufacturer's instructions.
Thermocouple leads shall be taken to suitable terminals in pits or terminal
boxes supplied and installed by the Contractor. Earthing link box pits may be
used where appropriate.
13.10Controlled Bedding in Cable Trenches
A controlled bedding consisting of approximately a 14:1 sand/cement mix shall
be used in the immediate vicinity of the cables and conduits. The sand should
be 5% OMC. A depth of at least 100 mm of the bedding material is required
both beneath and covering the power cables/conduits. The cement used shall
be to the current Australian Standard.
The sand used in the controlled bedding shall comply with the requirements of
Clause 9.0 of this Technical Standard.
The cable manufacturer may require a greater depth of controlled bedding (e.g.
to incorporate the 50C isotherm).
The cable rating shall be maintained under the most unfavourable conditions
and when the bedding material is completely dry. Under these conditions the
thermal resistivity of the controlled bedding shall not exceed 1.2C m/W.
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The Contractor shall compact the controlled bedding material to ensure that
there are no air spaces left, particularly in the close vicinity of the cables,
which would give rise to an increase in the external thermal resistance.
Mechanically operated rammers shall not be used for this purpose.
The contractor shall supply a sample of their proposed 14:1 sand/cement
bedding mix for testing by ETSA Utilities. The supply shall be contained in a44 gallon drum.
13.11Bentonite Mixture in Conduits
Where power cables are installed in conduits and the cable design requires
maintaining the thermal resistivity requirements and when specified by ETSA
Utilities, conduits shall be filled with a Bentonite based slurry mixture. The
conduits shall be completely filled with a Bentonite mixture. The Bentonite
mixture shall consist of 100 parts water, 10 parts Bentonite 20 parts sand and 8
parts cement such that the mixture can be readily pumped by means of a
centrifugal pump into the conduits.
To pump the mixture into the conduits they must first be filled with water.
Then the mixture shall be pumped to completely displace the water in the
conduit. The mixture shall have a thermal resistivity value of less than 1.2C
m/W in the settled condition.
13.12Protective Cover Slabs
The Contractor shall supply and install polymeric cover slabs, as per the
current Australian Standard, placed over the cables in a continuous line so that
the edge of the slab shall overlap the edge of any cable by not less than 50 mm
unless the space between cables does not permit this. In such a case, a full
width cover slab shall be used or, alternatively, a number of slabs buttedtogether so that there is no longitudinal joint over a cable.
One face of each slab shall be finished smooth and imprinted with "66 000
VOLT CABLES" in letters 40 mm high minimum.
All earthing cables shall also be protected with cover slabs.
13.13Backfilling
Refer to the requirements of Clause 11.0 of this Technical Standard.
Before backfilling the contractor will obtain a certificate of compliance from
ETSA Utilities to certify that the cable depth, cable spacing and bedding have
been adhered to.
Where long sections of conduit are installed, the trench is to be back-filled as
soon as practicable without waiting for cable laying unless directed by the
DaNM Project Manager to wait. Survey sketches must be prepared and
photographs must be taken prior to backfilling the trench.
13.13.1 Sand Backfill
Sand backfill shall be used on top of controlled bedding (refer section
13.10) and must completely fill the trench to near-surface level unless
agreed otherwise with DaNM Project Manager. At and near surface
level, any standard or specific backfill instructions by land-owners,councils or Government Departments are to be followed where
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appropriate. As a minimum, surfaces shall be reinstated to the same
condition as prior to excavation.
Sand backfill shall comply with the following:
TEST METHOD TESTPERMITTED TEST
VALUES
Grading Sieve Sizes (mm) AS1152-
1993Percent Passing
6.7 100
4.75 70-100
2.36 35-100
0.425 25-70
AS1141.11-1996
0.075 8-20
AS1289.3.1.2-1995 Liquid Limit Maximum 25
AS1289.3.3.1-1995 Plasticity Index Maximum 6
AS1289.3.4.1-1995 Linear Shrinkage Maximum 3
Where a sand backfill has been selected for its thermal properties and
does not fully satisfy the above grading requirements the thermal
requirements shall take precedence but the matter shall be referred to
ETSA Utilities for approval.
Any backfill containing clay or lumps of clay will be rejected.
13.14Cable Marker Tapes
Orange coloured plastic cable marker tapes of an approved type shall be
installed longitudinally in all trenches at a depth of approximately 400 mm
below the surface and in accordance with following:
Trench Width No. of Tapes
500 mm 1
500-1000 mm 2
1000-2000 mm 3
13.15Cable Markers
Cable markers shall be supplied and installed by the Contractor in parklands,
where the cable crosses footpaths and in any other location as may be required
by ETSA Utilities. The cable marker design and method of installation shall
be approved by ETSA Utilities.
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13.16Pits
Pits shall be provided for earthing link boxes and any other equipment installed
below ground level to which periodic access will be required.
The floor shall be constructed of concrete and shall include a suitable sump
cavity for pumping water drainage.
Walls shall be concrete and covers shall be standard "Gatic" type suitable forroadway or footway duty as required.
Drawings of pits shall be submitted to ETSA Utilities for approval.
13.17Jointing of Bays
Joint bays shall be constructed large enough for jointers to carry out the work
efficiently. The joint bay floor shall be a reinforced concrete slab not less than
100 mm thick with side walls of brick or concrete to a minimum height of 800
mm above the floor.
14.0CONTAMINATED SOILWhere ETSA Utilities constructs the Works, it is the Applicant's responsibility to
ensure that the soil is free from any contaminants that may be a risk to the health of
ETSA Utilities distribution workers. Written assurance may be required to
demonstrate that the soil is free from contamination and if necessary a report
detailing known contamination and steps taken to alleviate the health risks. Further
testing may be required before ETSA Utilities agrees to work on the site.
15.0CIVIL WORKS COMPLIANCE
Part of ETSA Utilities regulatory requirements includes an undertaking that any
electrical installation is compliant. Civil works and conduit installation forms a partof the ETSA Utilities electrical asset and must be at a standard that satisfies all of the
relevant ETSA Utilities standards and specifications.
To assist in the verification that the civil works are to standard a Civil Work
Compliance form is required from the civil contractor as part of the electrical
compliance.
There is a spreadsheet that details responsibilities for both the Civil Works
Notification form and the Civil Works Compliance form in appendix A of this
specification.
A Non Compliance notice and the relevant charge will be issued to the responsiblecontractor for any civil works installation that will ultimately be the responsibility of
ETSA Utilities and is found to not meet the ETSA Utilities specification.
Any Civil works related Non Compliance must be addressed prior to ETSA Utilities
accepting the Civil Works Compliance form. Any fees due to ETSA Utilities that
are associated with any Non Compliance must be paid in full prior to the final
electrical connection.
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15.1 Civil Works Notification
Civil works form a component of the asset inspection and vesting process. The
Civil Works Notification form NICC-453 (refer to sect 15.0 for access to the
form) must be submitted to the appropriate ETSA Utilities representative. The
following notice is required:
A section (contestable projects) 10 working days noticeB section 5 working days notice
15.2 Civil Works Compliance
The Civil Works Compliance form NICC-452 (refer to sect 15.0 for access
to the form) must be completed by the civil contractor and forwarded on to the
Electrical Contractor or the nominated ETSA Utilities Officer. Non receipt of
this form will in some cases prevent powerline or underground work
commencing.
The form is an integral component of the Certificate of ETSA Utilities
Electrical Compliance. If it is not available at the time of the final asset audit
and sign off there is the possibility that the customers connection will bedelayed.
16.0FURTHER INFORMATION
A comprehensive listing of information bulletins and forms that are of interest to a
customer and a contractor can be found on the ETSA Utilities web page
www.etsautilities.com.au for external users. Open Technical Standards.
Any ETSA Utilities employee has access via the Intranet index and opening up
Network/Quality Management Systems/Network Information.
Some of the information that is relevant to this technical standard include thefollowing;
Civil Contractors Utilised by ETSA Utilities - NICC-203
For a DTEI road: The Notification of Works Impacting SA Roads - NICC-251
For a ra