trenching for underground cables
TRANSCRIPT
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E T S A U t i l i t i e s D e l i v e r i n g e n e r g y t o S o u t h A u s t r a l i a n s
ETSA Utilities, ABN 13 332 330 749,
a partnership of:CKI Utilities Development Limited,
ABN 65 090 718 880.
HEI Utilities Development Limited,
ABN 82 090 718 951.
CKI Utilities Holdings Limited,
ABN 54 091 142 380.
HEI Utilities Holdings Limited,
ABN 50 091 142 362.
CKI/HEI Utilities Distribution Limited,
ABN 19 091 143 038.
each incorporated in The Bahamas
Copyright2004
TRENCHING AND CONDUIT STANDARD
FOR
UNDERGROUND CABLE NETWORKS
Technical Standard TS-085
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1.0 DEFINITIONS
The term "ETSA Utilities" means :-
ETSA Utilities, ABN 13 332 330 749, a partnership of:
CKI Utilities Development Limited, ABN 65 090 718 880.
HEI Utilities Development Limited, ABN 82 090 718 951.
CKI Utilities Holdings Limited, ABN 54 091 142 380.
HEI Utilities Holdings Limited, ABN 50 091 142 362.CKI/HEI Utilities Distribution Limited, ABN 19 091 143 038.
each incorporated in The Bahamas
1 Anzac Highway, Keswick, South Australia, 5035.
2.0 BACKGROUND
The responsibility for the installation of a trench for the installation of ETSA Utilitiesinfrastructure can be:
The developer for land developments or a customer for network extensions andalterations to the ETSA electrical network.
Council for Power Line Environment Committee (PLEC) projects.
ETSA for capital works and, under specific arrangements, some customer 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 therequirements 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
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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 infrastructure will be at the cost of the
responsible party. If any party is aware of any damage to the electrical infrastructure,ETSA 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 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 the developer/customers cost.
If there are any queries on this Technical Standard (TS 085) the 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 tonnesfor a 2000 kVA transformer. There may be a requirement to establish a retaining wall
to ensure the transformer has a stable footing. 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 natural (unchanged) ground
level of 300 mm or more within two metres of the standard easement boundary for the
electrical equipment.
Any retaining wall above 1.0 metre in height will require engineering confirmation of
the design and Council approval.
A R t i i ll t b l t d i t th i t ll ti f d t d
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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 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 to
the 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 ofsilt size.
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, and
medium 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.
Easement to be
Area for ETSAEquipment (onstandardeasement, 3.5 x2.5 m).
Retaining Wall
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RETAINING WALL - FILL Figure 2Retainingwall
ETSATransformer/switching cubicle
300mmminm
Granulated materialbehind all retainingwall sections
Continuous agriculturalpipe the length all retaining
wall sections plus externalweep holes on the lowestsection of the retaining Ground level
NoteRetaining wall to be
built up to the heightof the base
Weep hole
Suitable retaining
Ground level
300mmWeep hole
Ag pipe to exit at thefront of the retaining wall
Ground level
Continuous agriculturalpipe the length all retainingwall sections plus externalweep holes on the lowestsection of the retaining
RETAINING WALL - CUT Figure 3
Retaining WallWith 100mm lipabove ground
ETSATransformer/switching cubicle
Groundlevel
PreferredEasement
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 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.
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There shall be a minimum separation of 50mm between direct laid ETSA cable
circuits. The greater the cable circuit separation, the greater the current carrying
capacity of the electrical cable. If the trench width is such that the minimumseparation can be increased and the 50mm clearance to the trench 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 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 may approve a lesser dimension if it canbe 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 infrastructure in this standard are the minimum except where
shown.
The maximum depth of any length of trench or conduit should not be greater then 1.5
metres unless ETSA 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 the publication A Code
for the Placement of Infrastructure Services in New and Existing Streets (Services inStreets Code) prepared by the Public Utilities Advisory Committee (PUACC) and
available from the Local Government Association.
All variations to the Construction drawing mustbe noted by the installation contractor
d i l d d th A C t t d ETSA d i
Cables
50mm
Cable circuit separation50mm minimum (refer 4.1)
25mm
25mm
Bottom of trench
Conduit
Bedding Sand
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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.
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.
Conduits installed at a road crossing that are for a direct buried cable installation shallextend 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 Transport SA Roads
Transport SA have very specific requirements for any work being undertaken on a
Transport SA (TSA) controlled road. The requirements include both excavation and
traffic management and apply to overhead and underground works.
The Transport SA specification for the Excavation and Reinstatement of RoadPavement is available from TSA on (tel 82268222). ETSA Utilities recommends that
any contractor involved with the installation of either underground or overhead
electrical works on a TSA road obtain the latest TSA 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 TSA have
highlighted most TSA 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 84045439.
Some of the relevant sections of the specification dated February 2003 are detailed
below
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4.3.2. Trenchless method
Multiple conduits can be passed through a single bore or tunnel. There is arequirement though for multiple bores to have a minimum spacing of 10D
between individual bores.
where D = the diameter of the largest conduit.
The minimumdepth of a trenchless bore is 1.5 metres.
4.3.3. TSA Notification
The designer
The electrical designer should submit any design to TSA for comment where
any ETSA infrastructure, ie, poles, cable or conduit, will be running parallel
to the kerb for some distance. This is to ensure any installation takes intoaccount 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 TSA road over a period greater then one day requires 4
weeks notice.
The notice is required for the following:
Any work that requires traffic managementThis includes work on overhead mains
A t h d t hl b i
Minimum1.5 metres
Ground level
10 X 125mm =1.25m minimum100mm conduit
125mm conduit
Bore 1 Bore 2
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There is a requirement that TSA 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.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
TSA requires verbal notification to the appropriate TSA representative 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.
4.3.6. Maintenance Period
The contractor undertaking the civil component of the electrical worksassociated with the TSA road crossing will be responsible for the cost of
making good any settlement or other deteriation 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 andpipelines 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 of 28working days prior to any work taking place and forwarded to;
ETSA Utilities Easements Coordinator
level 3, 1 Anzac Highway Keswick 5035
Telephone 84045897 fax 84045193
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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 in a railwayproperty must have 1 metre minimum cover. A railway authority may approve a
lesser depth, but the depth must not be less then the ETSA Utilities standard.
4.5 Clearances between Services.
Comms
plant pipe
Comms
plant pits
Gas pipes ETSA LV
power
ETSA HV
power
Comms
plant pipe
150 150 200 100 300
Comms
plant pits
150 1000 200 100 100
Gas pipes 200 200 X 200 200
ETSA LV
power
100 100 200 X X
ETSA HV
power
300 100 200 X X
X = undefined in this application. All clearances are in millimetres
Comms = Telecommunications
Note: These clearances are applicable for the full circumference of the service (360)
These are minimum separations. For any other authority a minimum separation of150mm is required. Greater separation may be requested in the ETSA specification
from time to time.
To achieve these clearances it may be necessary to increase the cover on ETSA cables
and/or conduit or increase the trench width.
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.
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conduits. Appropriate bends with the smallest radius 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 Utilitiespriorto construction.
Below are some examples of conflict and possible solutions
Preferredgradient rise/fall
of conduit100mm per
1metre
ETSAconduit
Note
IfY > 1.5m it may bepreferreble to goover service.
150mmminimumunder service.
G.L.
XSharp bends
X Couplinglocation is notappropriate if there isany tension. This
creates a lip whichcan damage cables
`Y
INCORRECT PREFERRED
G.L.
AlternativeConduit
route
The example shows an in-appropriate conduit coupling with tension applies to both a
straight length of conduit and a bend.
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 theElectricity Corporations Act 1999 the SA Independent Regulator can impose a fine for
any breach.
Part 6 of this Act states the following:
38. (1) A person must not, without the written authority of the electricity
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A trench will normally be 600 mm wide but could be up to 1200 mm wide depending
on soil type and footpath location. With consultation with the electrical contractor, a
width of 450 mm may be acceptable. 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.
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 TRENCHmain Side
KERB
LV HV P/L
50mm
1000 mm
Spare conduit
Cables buried direct
Top of
bedding sand
Notes
Refer section 4.1
50mm
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
SPARE CONDUIT
Notes
Refer section
4.1
LV HV P/L
road level
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should be installed for any future cable installations. This method of installation
minimises disruption to footpath and vehicular traffic and business premises.
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
section4.1
Additional conduitRefer 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
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.
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 the entry of foreign material between the time of
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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
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 betweenfenced allotments)
Cables installed through easements.
Public lighting cables
Retrospective undergrounding (i.e. PLEC Projects)
On private property where cables vest in ETSA Utilities (Refer to section
6.0 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.
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.
11kV cables must not be installed in the same conduit as low voltage cables
5.2 Spare conduit provision
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For the high voltage: 3x 80mm VLD conduit
Note: Where one LV circuit consists of two or more parallel bundles of
cables, a spare conduit must be provided for each bundle of cables.
5.2.2 When a cable is installed in a conduitTo ensure future access to ETSA 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 specification the requirement is:
A PLEC project One spare conduit forallof the low voltage circuits
One spare conduit forallof the high voltage circuits up to
and including 300mm2.
One spare conduit per phase for any 630mm2 high voltage
installation
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 80mm (or 100mm) conduits and one 300mm2 high voltage
cable with one phase installed in a each of 3 x 80mm 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
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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.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 80mm VLD 1800 radius, Light duty
HV 35mm2 1 x 80mm VLD 1800 radius, Light duty
HV 95mm2 1 x 100mm VLD 1800 radius, Light dutyHV 300mm2 and
630mm2
3 x 80mm VLD 1800 radius, Light duty
Public Lighting 1 x 32mm HD 312 radius, Heavy duty
CBD installation No x 125mm VLD
The ETSA standard class 4.5 is equivalent to very light duty (VLD)
The ETSA standard class 6.0 is equivalent to light duty (LD)
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 Australian 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, eg ELECTRICAL DUCTING 100 mm
4.5 class. No other form of rigid conduit is permitted without the approval of the
Network Standards Manager .
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c)be light orange in colour. Black conduit with orange stripes may be utilisedwith 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 current rating.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.
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
b i ll f f l d i l h i di i i f 6
Floor of trench /opening for bore
Edge ofentry/exithole
Securing the end of directional boring conduit
Directionalboring conduit
End of polyethylenepipe to be concreteencased orsandbagged
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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 be positioned
horizontally.
Conduits between new and existing subdivisions must be joined together.
Cable markers are required wherever ETSA conduits/ cables pass through private
property. Refer to E1979 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 polyethylene expanded foam applied in accordance with the 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 NoCap, push on 40mm for consumers conduit
Cap, push on 50mm for consumers conduit NC 6462
Cap, push on 80mm NC 6470
Cap, push on 100mm NC 6501
Scrunched plastic ornewspaper
Cable
Approx 75mm
Expanding foam
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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.
The general trench configuration shall be in accordance with the following diagrams.
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
1000 mmPOLYMERIC
COVER SLAB
5mm thick
50mm75mm
maxm
Diagram C
Cable buried direct
N t
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Spare conduit
Cables buried direct
Public lighting can be
in conduit or buried
direct
50mm
1000 mmBEDDING
SAND
50mm
750mm
Notes
Refer section 4.1
ROAD VERGE -
SINGLE CUSTOMER
Any ETSA cable system that needs to be located under a road needs to satisfy either the
requirements detailed in section 4.5. for common service trenches or section 4.3 if it is a
Transport SA 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
600mm with warning tape installed at 400 mm.
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 infrastructure.
8.0 EXCAVATION FOR VAULTS
The excavation for vaults 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) Switching Cubicle Vaults:
the dimensions are in the order of 2250 long x 1000 wide x 1175 deep, totallingapproximately 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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Some common sand types are designated as DS4B and PM64. The specification for these
types differs from the ETSA standard. It is the contractors responsibility to ensure the
installed sand meets the ETSA specification.
TEST METHOD TEST PERMITTEDTEST VALUES
Grading Percent Passing
AS1141.11 Sieve Sizes mm
AS1152 4.75 100
2.36 98 - 100
1.18 94 - 100
0.6 85 - 100
0.425 55 - 100
0.3 25 - 100
0.15 5 - 40
0.075 0 - 10
AS1289 C3.1 Plasticity Index Maximum 6
(non plastic)
10.0 POLYMERIC 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 infrastructure and must overlap the ETSA
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
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Backfilling material must be clean and completely free from all fibrous and vegetable
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 sandprovided 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 conduits are laid beneath other buried services, the backfill beneath suchservices is adequately compacted such that :
(a) no voids between conduit layers, and
(b) the other buried service(s) is adequately supported to prevent damage.
Consolidation of the backfilled excavations will be in accordance with the local
Council or Transport SA specifications as appropriate.
12.0 CIVIL WORKS
12.1 Applicants Responsibilities
The Applicant or an agent of the applicant shall be responsible for:
Ensuring that all allotment pegs, including any replacement pegs, easementpegs 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 the Applicant'sworks. This includes ensuring that there is suitable clearance between any
excavation and existing ETSA infrastructure, including poles and footings. A
financial penalty can be applied by the industry Regulator for any unlawfull
interference
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Damage caused to vaults and associated equipment during backfilling andcompaction
13.0 CONTAMINATED SOIL
Where 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.
14.0 CIVIL WORKS COMPLIANCE
Part of ETSA Utilities regulatory requirements includes an undertaking that any
electrical installation is compliant. Civil works and conduit installation forms a part of
the ETSA 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.
14.1 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 notice
B section 5 working days notice
14.2 Civil Works Compliance
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www.etsautilities.com.au for external users. Open services/business services/Network Information
Any ETSA Utilities employee has access via the Intranet index and opening upNetwork/Quality Management Systems/Network Information.
Some of the information that is relevant to this technical standard include the
following;
Civil Contractors Utilised by ETSA Utilities - NICC-203
For a TSA road: The Notification of Works Impacting SA Roads - NICC-251
For a railway line: Application to Cross Railways With Electric Power CablesNICC-252
Civil Works Notification form NICC-453
Civil Works Compliance form NICC-452
Terms & Conditions for Network Installation by a Contractor
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Issued: April 05 TS -085 Authorised: J Ali 11/04/05 Appendix A
CIVIL WORKS NOTIFICATION & COMPLIANCE RESPONSIBILITY
CaMS / BSO
(minor works only)
CaMS / ContractSvisor (minor &
major project)
CPO
(major projects only)
Customer (whenresponsible for
trenching)
Civil Contractor
Civil Works notification form NICC - 453 Intranet: Network/QMS/Network Information
Customer doing thetrenching
1. Fill in B:Contract Supervisor/ TSW8
2. Issue to customer
1. Insert point ofcontact:Compliance Co-ord
2. Issue to customeras part of
information pack
Customer to forwardform to the contractedcivil contractor
Return form to:A for a contestable
projectB for all other projects
(Contract
Supervisor / TSW8)
ETSA doing thetrenching
1. Fill in B:Contract Supervisor/ TSW8
2. Issue to civilcontractor
Return form to:Contract Supervisor/ TSW8
Civil Works Compliance form NICC - 452 Intranet Network/QMS/Network Information
Customer doing thetrenching
1. Insert name ofContract Supervisor/ TSW8
2. Issue to customer
1. Highlight point ofcontact as electricalcontractor
2. Issue as part ofinformation pack
1. Customer to insertelectrical contractordetails
2. Forward form tocivil contractor
Return form to:Electrical contractor.If unknown, thecustomer
ETSA doing the
trenching
1. Fill in ETSAContract Supervsor/ TSW8
2. Issue to civilcontractor
Return form to:Electrical contractor.If unknown, Contract
Supervisor / TSW8
Note: The Civil Works Compliance form must be completed for all projects with a trenching component as
it is a prerequisite to acceptance of the Certificate of ETSA Utilities Electrical Compliance