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Trenching & Conduit Standard For Underground Cable Networks - TS - 085

Issued: December 2008 TS - 085 Authorised: J Ali 12/12/08 Page 1 of 31

Disclaimer refer www.etsautilities.com.au

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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Page 2 of 34

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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Page 3 of 34

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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Issued: December 2008 TS - 085 Authorised: J Ali 12/12/08 Page 4 of 31


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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Trenching & Conduit Standard For Underground Networks - TS-085



Page 5 of 34

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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Page 7 of 34

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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Page 8 of 34

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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Page 9 of 34

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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Page 11 of 34

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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Page 12 of 34

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


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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Page 13 of 34

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


500 for

sewer main

300


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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Page 14 of 34

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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Page 15 of 34

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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Page 18 of 34

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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Page 19 of 34

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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Page 20 of 34

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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Page 21 of 34

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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Page 22 of 34

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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Page 23 of 34

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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Page 24 of 34

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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Page 26 of 34

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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Page 27 of 34

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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Page 29 of 34

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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Page 30 of 34

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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Page 31 of 34

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

ts085 trench conduit standard uground cable network

Documents