Network Standard...of structure and person who commissions construction work) which requires the designer to provide a written safety report to the person who commissioned the design

NW000-S0071 UNCONTROLLED IF PRINTED Page 1 of 47

Network Standard

NETWORK

Document No Amendment No Approved By Approval Date Review Date

:::::

NW000-S0071 0 Head of AEP & S 28/05/2015 31/03/2019

(Review Date Changed - 06.02.2019)

NW000-S0071 NS126 CONSTRUCTION OF HIGH VOLTAGE OVERHEAD MAINS

NS126 Construction of High Voltage Overhead Mains Amendment No 0


ISSUE

For issue to all Ausgrid and Accredited Service Providers’ staff involved with the design and installation of overhead lines, and is for reference by field, technical and engineering staff.

Ausgrid maintains a copy of this and other Network Standards together with updates and amendments on www.ausgrid.com.au.

Where this standard is issued as a controlled document replacing an earlier edition, remove and destroy the superseded document

DISCLAIMER

As Ausgrid’s standards are subject to ongoing review, the information contained in this document may be amended by Ausgrid at any time. It is possible that conflict may exist between standard documents. In this event, the most recent standard shall prevail.

This document has been developed using information available from field and other sources and is suitable for most situations encountered in Ausgrid. Particular conditions, projects or localities may require special or different practices. It is the responsibility of the local manager, supervisor, assured quality contractor and the individuals involved to make sure that a safe system of work is employed and that statutory requirements are met.

Ausgrid disclaims any and all liability to any person or persons for any procedure, process or any other thing done or not done, as a result of this Standard.

All design work, and the associated supply of materials and equipment, must be undertaken in accordance with and consideration of relevant legislative and regulatory requirements, latest revision of Ausgrid’s Network Standards and specifications and Australian Standards. Designs submitted shall be declared as fit for purpose. Where the designer wishes to include a variation to a network standard or an alternative material or equipment to that currently approved the designer must obtain authorisation from the Network Standard owner before incorporating a variation to a Network Standard in a design.

External designers including those authorised as Accredited Service Providers will seek approval through the approved process as outlined in NS181 Approval of Materials and Equipment and Network Standard Variations. Seeking approval will ensure Network Standards are appropriately updated and that a consistent interpretation of the legislative framework is employed.

Notes: 1. Compliance with this Network Standard does not automatically satisfy the requirements of a Designer Safety Report. The designer must comply with the provisions of the Workplace Health and Safety Regulation 2011 (NSW - Part 6.2 Duties of designer of structure and person who commissions construction work) which requires the designer to provide a written safety report to the person who commissioned the design. This report must be provided to Ausgrid in all instances, including where the design was commissioned by or on behalf of a person who proposes to connect premises to Ausgrid’s network, and will form part of the Designer Safety Report which must also be presented to Ausgrid. Further information is provided in Network Standard (NS) 212 Integrated Support Requirements for Ausgrid Network Assets.

2. Where the procedural requirements of this document conflict with contestable project procedures, the contestable project procedures shall take precedent for the whole project or part thereof which is classified as contestable. Any external contact with Ausgrid for contestable works projects is to be made via the Ausgrid officer responsible for facilitating the contestable project. The Contestable Ausgrid officer will liaise with Ausgrid internal departments and specialists as necessary to fulfil the requirements of this standard. All other technical aspects of this document which are not procedural in nature shall apply to contestable works projects.

INTERPRETATION

In the event that any user of this Standard considers that any of its provisions is uncertain, ambiguous or otherwise in need of interpretation, the user should request Ausgrid to clarify the provision. Ausgrid’s interpretation shall then apply as though it was included in the Standard, and is final and binding. No correspondence will be entered into with any person disputing the meaning of the provision published in the Standard or the accuracy of Ausgrid’s interpretation.

KEYPOINTS

This standard has a summary of content labelled “KEYPOINTS FOR THIS STANDARD”. The inclusion or omission of items in this summary does not signify any specific importance or criticality to the items described. It is meant to simply provide the reader with a quick assessment of some of the major issues addressed by the standard. To fully appreciate the content and the requirements of the standard it must be read in its entirety.

AMENDMENTS TO THIS STANDARD

Where there are changes to this standard from the previously approved version, any previous shading is removed and the newly affected paragraphs are shaded with a grey background. Where the document changes exceed 25% of the document content, any grey background in the document is to be removed and the following words should be shown below the title block on the right hand side of the page in bold and italic, for example, Supersedes – document details (for example, “Supersedes Document Type (Category) Document No. Amendment No.”). .

KEY POINTS OF THIS STANDARD


Covered Conductor Thick (CCT) Details

Bare Conductor Arrangements

Single Wire Earth Return (SWER) and Other Sections Scope and Risks Addressed

Tools and Forms None

Tools and Forms Annexure B Sample compliance checklist

This standard is limited to scope identified below and provides controls for associated risks as listed below:

Concerns the construction requirements for 11kV, 22kV or 12.7KV SWER overhead lines within Ausgrid supply network area.

Ausgrid’s requirements for LV overhead mains is covered separately in NS125 and Subtransmission voltage overhead mains in NS135.

Ausgrid will determine which type of HV overhead mains system is to be used in a given situation.

Covered Conductor Thick (CCT) mains is used in select locations to reduce risks associated with bush fires, conductor clashing and reduced phase separation.

Lightning protection shielding principles are reviewed in Annexure A.

Where to for more information? Section 1, 2, 5, Annexure A

This section provides details of major design requirements for CCT construction and includes the following:

Details of o Covering material o Conductor used o Electrical and mechanical

characteristics o Line design parameters o Insulator requirements o Lightning Protection provisions o CCT fittings and insulating covers o CCT crossarms o Pole-top operating devices,

capacitors, and regulators o Pole mounted

substations/transformers Electrical safety requirements

associated with operating and access for CCT lines are provided.

Special erection considerations and precautions are provided.

CCT conductor standard construction drawing list is provided.

This section provides details of major design requirements for bare conductor construction and includes the following:

Details of o Manufacturing requirements

based on Australian Standards o Electrical and mechanical

characteristics o Line design parameters o Insulator requirements o Lightning Protection provisions o BC fittings o BC crossarms o Pole-top operating devices,

capacitors, and regulators o Pole mounted

substations/transformers Electrical safety requirements

associated with operating and access for BC lines are provided.

Special erection considerations and precautions are provided.

BC conductor standard construction drawing list is provided.

This section provides details of major design requirements for SWER construction and includes the following:

Principles of SWER systems Details of SWER line design and

substation requirements SWER standard construction drawing

list is provided. General Design Parameters for CCT,

BC and SWER systems are provided and include: o Structural design requirements o Pole foundations o Rail crossings o Crossing navigable waterways o Provision of Network Project

Design Plan Electrical Safety principles tobe

followed Clearance information Pole installation Testing overhead construction Access to stores and materials.

Tools and Forms None

Where to for more information? Section 6

Where to for more information? Section 7

Where to for more information? Section 8 -14



Network Standard NS126

Construction of High Voltage Overhead Mains

Contents

1.0 PURPOSE ............................................................................................................................................. 7

2.0 SCOPE .................................................................................................................................................. 7

3.0 REFERENCES ...................................................................................................................................... 7 3.1 Ausgrid documents .................................................................................................................... 7 3.2 Other standards and documents ................................................................................................ 8 3.3 Acts and regulations................................................................................................................... 8

4.0 DEFINITIONS ........................................................................................................................................ 9

5.0 INTRODUCTION ................................................................................................................................. 10 5.1 Application of 11kV distribution mains ..................................................................................... 10

6.0 COVERED CONDUCTOR THICK (CCT) DETAILS ............................................................................ 11 6.1 General details ......................................................................................................................... 11

6.1.1 Covering ....................................................................................................................... 11 6.1.2 Water-blocking compound ........................................................................................... 11 6.1.3 Conductor alloy ............................................................................................................ 11

6.2 Covered conductor thick line design ........................................................................................ 12 6.2.1 Phasing ........................................................................................................................ 12 6.2.2 Clearances and spacing ............................................................................................... 12

6.3 Insulators .................................................................................................................................. 13 6.4 Lightning Protection ................................................................................................................. 14

6.4.1 General ......................................................................................................................... 14 6.4.2 Surge arresters ............................................................................................................. 14 6.4.3 Polymeric surge arrester .............................................................................................. 15 6.4.4 Current limiting arcing horn (CLAH) ............................................................................. 15 6.4.5 Insulation co-ordination ................................................................................................ 16

6.5 CCT Fittings and insulating covers .......................................................................................... 16 6.5.1 General ......................................................................................................................... 16 6.5.2 Strain clamp and cover ................................................................................................ 16 6.5.3 Parallel groove clamp and cover .................................................................................. 17 6.5.4 Standard earthing point and cover ............................................................................... 17 6.5.5 Tie wires ....................................................................................................................... 18 6.5.6 Full tension joint ........................................................................................................... 18 6.5.7 Compression lugs ......................................................................................................... 19

6.6 CCT crossarms ........................................................................................................................ 19 6.6.1 Crossarm for post insulators ........................................................................................ 19

6.7 Pole-top operating devices ...................................................................................................... 19 6.8 Pole substations/transformers ................................................................................................. 19 6.9 Regulators ................................................................................................................................ 19 6.10 Capacitors ................................................................................................................................ 19 6.11 Electrical safety procedures ..................................................................................................... 19

6.11.1 Isolation and proving de-energised .............................................................................. 20 6.11.2 Earthing and short-circuiting ........................................................................................ 20



6.11.3 Identification ................................................................................................................. 20 6.12 Erection of CCT lines ............................................................................................................... 20

6.12.1 Precautions .................................................................................................................. 20 6.12.2 Angle of deviation specifications .................................................................................. 21

6.13 11kV UGOH constructions ....................................................................................................... 21 6.14 Construction diagrams of covered conductor thick arrangements .......................................... 21 6.15 General details ......................................................................................................................... 24 6.16 Bare conductor line design ...................................................................................................... 24

6.16.1 Phasing ........................................................................................................................ 24 6.16.2 Clearances and spacings of bare conductors .............................................................. 25 6.16.3 Vibration dampers ........................................................................................................ 25

6.17 Insulators .................................................................................................................................. 25 6.17.1 Through constructions .................................................................................................. 25 6.17.2 Termination constructions ............................................................................................ 25

6.18 Lightning protection .................................................................................................................. 26 6.19 BC Fittings ................................................................................................................................ 26

6.19.1 Parallel Groove (PG) clamp ......................................................................................... 26 6.19.2 Full tension sleeve ........................................................................................................ 26 6.19.3 Non-tension sleeve....................................................................................................... 26 6.19.4 Spiral vibration damper ................................................................................................ 26 6.19.5 Armour rod ................................................................................................................... 26 6.19.6 Compression lugs ......................................................................................................... 26 6.19.7 Preformed dead-end .................................................................................................... 26 6.19.8 Tie wire ......................................................................................................................... 26 6.19.9 Joint compound ............................................................................................................ 27

6.20 Crossarms ................................................................................................................................ 27 6.21 Pole-top operating devices ...................................................................................................... 27

6.21.1 Air break switches ........................................................................................................ 27 6.21.2 Pole mounted circuit breakers (reclosers) ................................................................... 27 6.21.3 Under-slung links .......................................................................................................... 27 6.21.4 Drop-out fuses .............................................................................................................. 27 6.21.5 Enclosed load break switches ...................................................................................... 27

6.22 Pole substations/transformers ................................................................................................. 27 6.23 Regulators ................................................................................................................................ 28 6.24 Capacitors ................................................................................................................................ 28 6.25 Erection of BC lines .................................................................................................................. 28 6.26 11kV UGOH constructions ....................................................................................................... 28 6.27 Construction diagrams of BC arrangements ............................................................................ 28

7.0 SINGLE WIRE EARTH RETURN (SWER) .......................................................................................... 31 7.1 General .................................................................................................................................... 31

7.1.1 Distribution systems ..................................................................................................... 31 7.1.2 Advantages .................................................................................................................. 31 7.1.3 Disadvantages .............................................................................................................. 31 7.1.4 Use ............................................................................................................................... 31

7.2 SWER line design .................................................................................................................... 32 7.3 SWER substations ................................................................................................................... 32 7.4 Construction diagrams of SWER arrangements ...................................................................... 32

8.0 DESIGN PARAMETERS ..................................................................................................................... 33 8.1 Design standards and parameters ........................................................................................... 33 8.2 Foundation design .................................................................................................................... 33 8.3 Railway crossings .................................................................................................................... 33



8.4 Crossings of navigable waterways ........................................................................................... 33 8.5 Additional design information ................................................................................................... 33

9.0 ELECTRICAL SAFETY PROCEDURES ............................................................................................. 34 9.1 Basic safety principles ............................................................................................................. 34 9.2 Proving de-energised ............................................................................................................... 34

10.0 CLEARANCES ..................................................................................................................................... 34 10.1 Clearance Criteria .................................................................................................................... 34

11.0 POLE INSTALLATION ......................................................................................................................... 35 11.1 General .................................................................................................................................... 35 11.2 Staying of poles with unbalanced loads ................................................................................... 35 11.3 Positioning of poles .................................................................................................................. 35

12.0 TESTING HV OVERHEAD CONSTRUCTION .................................................................................... 35 12.1 General .................................................................................................................................... 35 12.2 Phasing and insulation resistance ........................................................................................... 35 12.3 Minimum IR values ................................................................................................................... 35

13.0 STORES AND MATERIALS ................................................................................................................ 36

14.0 RECORDKEEPING ............................................................................................................................. 36

15.0 AUTHORITIES AND RESPONSIBILITIES .......................................................................................... 36

16.0 DOCUMENT CONTROL...................................................................................................................... 36

ANNEXURE A - LIGHTNING PROTECTION SHIELDING ............................................................................. 37 A1 Assumptions ............................................................................................................................. 37 A2 Additional information............................................................................................................... 37 A3 Explanations of graphs ............................................................................................................ 37 A4 Inclined lines ............................................................................................................................ 38

ANNEXURE B – SAMPLE COMPLIANCE CHECKLIST ................................................................................ 46



1.0 PURPOSE This Network Standard is Ausgrid’s specification for the construction of 11kV, 22kV or 12.7kV Single Wire Earth Return (SWER) Overhead lines within the Ausgrid Supply Network area.

Ausgrid’s requirements for Low Voltage overhead mains are detailed in NS125 Specification for Low Voltage Overhead Mains. Ausgrid’s requirements for subtransmission voltage overhead mains are detailed in NS135 Specification for the Design & Construction of Overhead Sub-transmission Lines. For other system voltages design and construction documentation will be issued by Ausgrid on a project specific basis.

2.0 SCOPE This Network Standard together with other referenced standards and guidelines describes Ausgrid’s construction requirements for 11kV, 22kV and SWER High Voltage (HV) Overhead (OH) mains.

The following types of HV OH mains systems are currently in use in the Ausgrid 11kV distribution network:

Bare Conductor (BC), and Covered Conductor Thick (CCT)

3.0 REFERENCES All work covered in this document shall conform to all relevant Legislation, Standards, Codes of Practice and Network Standards. Current Network Standards are available on Ausgrid’s Internet site at www.ausgrid.com.au.

3.1 Ausgrid documents Bush Fire Risk Management Plan Company Procedure (Governance) - Network Document Endorsement and Approval Company Procedure (Network) - Production / Review of Network Standards Company Form (Governance) - Network Document Endorsement and Approval Customer Installation Safety Plan Electrical Safety Rules Electricity Network Safety Management System Manual ES4 Service Provider Authorisation NEG OH14 Guide to the Assessment of Waterway Crossing Risks NS100 Field Recording of Network Assets NS104 Specification for Electrical Network Project Design Plans NS116 Design Standards for Distribution Earthing NS122 Pole Mounted Substation Construction NS125 Specification for Low Voltage Overhead Mains NS128 Specification for Pole Installation and Removal NS129 11kV Joints and Terminations – Paper Insulated Lead Covered Cables NS135 Specification for the Design & Construction of Overhead Sub-transmission Lines NS167 Positioning of Poles and Lighting Columns NS174 Environmental Procedures NS177 11kV Joints (including Transition Joints) & Terminations - Polymeric Insulated Cables NS179 Vegetation Safety Clearances NS181 Approval of Materials and Equipment and Network Standard Variations NS212 Integrated Support Requirements for Ausgrid Network Assets NS214 Guide to Live Line Design Principles NS220 Overhead Design Manual NS261 Requirement for Design Compliance Framework for Network Standards



NSA 1494 Polymeric Insulator Handling Guide Public Electrical Safety Awareness Plan Public Lighting Management Plan Policy for ASP/1 Premises Connections Tree Safety Management Plan TS4200 Fuse Standard

3.2 Other standards and documents AS 1154 Insulator and conductor fittings for overhead power lines - Series AS 1222 Steel conductors and stays – Bare overhead AS 1307.2 Surge arresters - Metal-oxide surge arresters without gaps for a.c. systems AS 1531 Conductors – Bare overhead, Aluminium and aluminium alloy AS 1746 Conductors – Bare overhead – Hard-drawn copper AS 1824.1 Insulation co-ordination - Definitions, principles and rules AS 1824.2 Insulation coordination (phase-to-earth and phase-to-phase, above 1 kV) -

Application guide AS/NZS 2947 Insulators - Porcelain and glass for overhead power lines - Voltages greater than

1000 V a.c. - Test methods AS 3607 Conductors – Bare overhead, Aluminium and aluminium alloy – Steel reinforced AS/NZS 3675 Conductors - Covered overhead - For working voltages 6.35/11(12) kV up to and

including 19/33(36) kV AS/NZS 3599.1 Electric cables - Aerial bundled - Polymeric insulated - Voltages 6.35/11(12) kV

and 12.7/22(24) kV - Metallic screened AS/NZS 3599.2Electric cables - Aerial bundled - Polymeric insulated - Voltages 6.35/11(12) kV

and 12.7/22(24) kV - Non-metallic screened AS/NZS 4676 Structural design requirements for utility services poles AS 6947 Crossing of waterways by electricity infrastructure AS/NZS 7000 Overhead line design - Detailed procedures Crossings of NSW Navigable Waters: Electricity Industry Code ENA Doc 001-2008 National Electricity Network Safety Code Relevant Industry and WorkCover Guides and Codes of Practice

3.3 Acts and regulations All pertinent Environmental Regulations and Acts Electricity Supply (General) Regulation 2014 (NSW) Electricity Supply (Safety and Network Management) Regulation 2014 Electricity (Consumer Safety) Act 2004 No 4 Electricity (Consumer Safety) Regulation 2006 Electricity Supply Act 1995 No 94 Electricity Supply (Corrosion Protection) Regulation 2008 Work Health and Safety Act 2011 and Regulation 2011



4.0 DEFINITIONS Accredited Service Provider (ASP)

An individual or entity accredited by the NSW Department of Planning and Environment, Energy, Water and Portfolio Strategy Division, in accordance with the Electricity Supply (Safety and Network Management) Regulation 2014 (NSW).

Business Management System (BMS)

An Ausgrid internal integrated policy and procedure framework that contains the approved version of documents.

Bare conductor (BC)

In this standard a bare conductor refers to a conductor (manufactured to AS1222, AS3607, AS1531 or AS1746) which is not covered or insulated.

Covered Conductor Thick (CCT)

An unscreened conductor around which is applied a specified thickness of insulating material for the nominal working voltage of 11kV.

Customer A customer is an individual or an entity that is an end-user of electricity.

Document control Ausgrid employees who work with printed copies of document must check the BMS regularly to monitor version control. Documents are considered “UNCONTROLLED IF PRINTED”, as indicated in the footer.

HDPE High-density Polyethylene.

High Voltage, Aerial Bundled Cable

A screened cable system used by Ausgrid for the high voltage overhead distribution system. The high voltage cable system consists of three compacted stranded hard-drawn aluminium conductors individually insulated with black cross-linked polyethylene (XLPE) and a steel support catenary wire.

High Voltage Distribution System

In this document the term High Voltage Distribution System means all mains and apparatus operating at nominal voltage of 11kV or single wire earth return (SWER) operating at 12.7kV.

Low Voltage Distribution System

All mains and apparatus operating at nominal voltages above 50 V (extra low voltage) and up to and including 1000 V.

Network Standard A document, including Network Planning Standards, that describes the Company's minimum requirements for planning, design, construction, maintenance, technical specification, environmental, property and metering activities on the distribution and transmission network. These documents are stored in the Network Category of the BMS repository.

Phasing (Phased) Means a test to determine whether energised conductors of phase A, B or C of one section of a polyphase system may be satisfactorily connected to the corresponding phases of another section of polyphase system.

PCC Peak Consultative Committee.

Project Officer Employees who review network standards as directed by section managers from Engineering, Network.

Review date The review date displayed in the header of the document is the future date for review of a document. The default period is three years from the date of approval however a review may be mandated at any time where a need is identified. Potential needs for a review include changes in legislation, organisational changes, restructures, occurrence of an incident or changes in technology or work practice and/or identification of efficiency improvements.

SWER Single Wire Earth Return. A HV distribution system consisting of a single active wire, and using the earth as the return path.

XLPE Cross-linked Polyethylene.



.

5.0 INTRODUCTION This Network Standard together with other referenced standards and guidelines describes Ausgrid’s construction requirements for 11kV, 22kV and Single Wire Earth Return (SWER) High Voltage (HV) Overhead Mains.

Three types of High Voltage overhead mains systems are currently in use in the Ausgrid 11kV distribution network.

Bare Conductor (BC),

Covered Conductor Thick (CCT), and

Aerial Bundled Cable (ABC) (see Note).

Note: No new HV ABC constructions shall be undertaken except under extraordinary circumstances and with express approval of Ausgrid Distribution Mains Engineering. Therefore details of only the two systems, BC and CCT, are documented in this Network Standard. SWER systems use BC only.

In all cases Ausgrid reserves the right to nominate which type of high voltage overhead mains system is to be used in any particular situation. In selecting the type of system Ausgrid considers technical, financial and environmental factors so as to strike a proper balance between the responsibility to provide a safe, economic and reliable supply of electricity and at the same time, preserve the environment.

All contestable works on or near Ausgrid Transmission and/or Distribution system falls under the category of Authorised Work and shall only be performed by an Accredited Service Provider and in accordance with the requirements of ES4 Service Provider Authorisation. Accredited Service Providers shall ensure that any person carrying out the above work is duly authorised. (Refer to ES4 and NS104 Specification for Electrical Network Project Design Plans).

Refer to Policy for ASP/1 Premises Connections for details of Ausgrid’s overhead and underground mains policy.

The general guidelines for the form of construction for each development shall be determined by Ausgrid and shall be in accordance with the prevailing policy of the time. The final interpretation and decision as to the type of construction to be used shall be Ausgrid’s. Notification of the type of construction shall be issued in the preliminary design brief.

5.1 Application of 11kV distribution mains The use of overhead 11kV mains in urban areas shall be in accordance with Policy for ASP/1 Premises Connections.

The use of overhead 11kV mains in non-urban areas shall be in accordance with Policy for ASP/1 Premises Connections. Where overhead mains are used, CCT should be used in the following situations:

Where there is a significant risk of tree branches falling onto the mains or wind-blown debris may come into contact with the mains, and disrupt supply or initiate bushfires etc.

Where reduced phase separation is required in narrow easements, or to reduce tree trimming. Where conductor clashing is a problem and wider phase separation of BC is not practicable.

In all other cases BC shall be used.



6.0 COVERED CONDUCTOR THICK (CCT) DETAILS 6.1 General details

The Covered Conductor Thick (CCT) system, although not a touch-safe screened cable system, is designed to provide protection from initiation of flash-overs due to clashing of conductors, bird or animal incursions, and tree branches or debris which has blown or fallen on to the line.

CCT is manufactured to comply with AS 3675 Conductors - Covered overhead - For working voltages 6.35/11(12) kV up to and including 19/33(36) kV.

6.1.1 Covering CCT shall have an inner insulating covering of cross-linked polyethylene (XLPE) and an outer sheath of black, UV stabilised, high-density polyethylene (HDPE) about 1 mm thick. The outer sheath has a high resistance to abrasion. Grey CCT is supplied with Schneider reclosers and enclosed high voltage switches.

The combined thickness of covering shall be 3.4mm.

6.1.2 Water-blocking compound Water-blocking compound is used to prevent migration of water along the conductor. The rubbery compound fills the interstices between strands and the space between the aluminium conductor surface and the covering.

6.1.3 Conductor alloy The conductor material of CCT normally used by Ausgrid is uncompacted AAAC/1120 aluminium alloy. However, in special situations such as high tension spans AAAC/6201 aluminium alloy may be required.

Alloy 6201 has a higher breaking load than Alloy 1120.

For example:

120mm2 Alloy 6201 has a breaking load of 34.8kN, compared to

120mm2 Alloy 1120, which has a breaking load of 27.1kN.

The choice of conductor material depends on site conditions and mechanical load considerations.

Ausgrid uses three conductor sizes: CCT80, CCT120, CCT180 (see Table 1 below for details).



Table 1 – Electrical and Mechanical Characteristics

Conductor Cable Code (As per NS100) CCT80 CCT120 CCT180

Stockcode 144519 147421 176311

Number of strands/wire diameter 7/3.75 7/4.75 19/3.50

Alloy type/grade AAAC/1120 AAAC/1120 AAAC/1120

Cross sectional area (mm2) 77.3 124.0 182.8

Equivalent alum. area (mm2) 73.7 118.2 173.5

Minimum breaking load (kN) 17.6 27.1 41.7

DC resistance at 20°C (Ω/km) 0.383 0.239 0.163

Diameter of conductor (mm) (approx) 11.3 14.3 17.5

Insulation thickness (mm) (min. av.) 3.4 3.4 3.4

Overall diameter range (mm) 17.9-19.4 20.9-22.4 24.1-25.7

Mass (kg/km) (approx.) 450 640 780

Current rating See Note. Refer NS 220 Overhead Design Manual - Section 6.

Modulus of elasticity (GPa) 65 65 65

Co-efficient of linear expansion (/°C) 23 x 10

-6 23 x 10-6 23 x 10-6

Minimum bending radius (mm) 285 330 380

Note: CCT180 current rating (Normal) under above conditions is 470 A. If larger loads are to be met (e.g. in place of Pluto which has a current rating (Normal) of approximately 600 A under similar conditions) multiple parallel conductors will be used, e.g. 2xCCT120 per phase.

6.2 Covered conductor thick line design CCT lines shall generally be designed in accordance with Section 9. In addition, the following requirements shall be observed.

6.2.1 Phasing The configuration of phases shall be according to the particular installation requirements as specified by Ausgrid. Where there are no installation constraints, the following configuration shall be used:

Phase A: Bottom conductor or footpath / property side Phase B: Centre conductor Phase C: Top conductor or road side

6.2.2 Clearances and spacing 6.2.2.1 Mid span clearances Mid span clearances between vertically spaced circuits shall be at worse case conditions for each span, i.e. top circuit at maximum operating temperature and bottom circuit at minimum operating temperature.



6.2.2.2 Phase to phase spacing for CCT For new vertical or delta (crossarm) construction the minimum phase-to-phase spacing between conductors should be 500mm.

6.2.2.3 Separation between covered conductors and low voltage aerial bundled cable or LV bare conductors

The separation between the CCT and LV ABC or LV bare conductors at the pole construction depends on whether the HV network can be worked on using live line techniques. Refer to NS 220 Overhead Design Manual - Section 10 for live-line circuit to circuit clearances. Midspan separation must not be less than that specified in AS7000 Overhead line design - Detailed procedures.

Note: Spur lines should always be designed and constructed with live-line circuit to circuit separations.

For further live-line design principles refer to NS214 Guide to Live Line Design Principles.

6.2.2.4 Clearances to ground, structures and vegetation The clearance of CCT to ground, structures and vegetation shall be in accordance with Section 11.

6.3 Insulators For line construction, solid-core type pin post insulators must be used. Standard pin insulators must not be used since they do not offer satisfactory lightning or electrical tracking performance which can damage and lead to the burn-down of the CCT. Solid-core type pin post insulators are available with long or short studs to suit crossarm or bracket mounting respectively.

Note: Conductor insulation must not be removed at the pin or post insulator.

Solid-core strain rod insulators and strain clamps must be used at termination points and with high angle deviation (>50° for horizontal configuration or >30° for vertical configuration). The strain rod insulator currently available has a tongue and clevis designed to attach to a strain clamp.

The following three types of insulators are available to suit different construction purposes:

Morlynn pin post Short stud Z = 45 mm Long stud Z = 145 mm

NGK pin post Short stud Z = 45 mm Long stud Z = 145 mm

NGK strain rod



6.4 Lightning Protection 6.4.1 General Compared to bare overhead lines, covered conductor lines are more prone to damage due to lightning. Therefore it is necessary to install suitable surge arrester arrangements on CCT lines. As CCT is generally used in treed or built up areas, the CCT distribution system has the advantage of benefiting from the shielding provided by the trees or structures. Guidelines to estimate the level of shielding provided by the existing objects are given in Annexure A. For line segments with more than 90% shielding, the distance between surge arresters may be approximately 500m. For more lightning prone locations such as hilltops Ausgrid will specify the appropriate surge protection to be used.

Additionally, surge arresters must be installed at CCT-BC transition points to prevent surges due to lightning strikes originating in the BC system entering the CCT system. If the transition point is an ABS the surge arresters should be installed one span away from the ABS on the CCT side.

Surge arresters shall be earthed in accordance with Ausgrid Network standard NS116 Design Standards for Distribution Earthing and shall be designed and constructed in accordance with the relevant drawings listed in Clauses 6.14 and 7.13.

The earth leads on S&C IntelliRupters shall be designed and constructed in accordance with the relevant drawings listed in Clauses 6.14 and 7.13.

6.4.2 Surge arresters Two types of Surge Arresters (class NS to AS 1307.2 Surge arresters - Metal-oxide surge arresters without gaps for a.c. systems) are available:

Table 2 – CCT Surge Arrester Stockcodes

CCT Cable 11kV Polymeric Arrester (see Note)

Current Limiting Arcing Horn (CLAH)

80mm² 150383 144675

120mm² 150383 144667

180mm² 150383 176322

If the design involves crossarms and the insulators are upright (e.g. reconstruction of an existing bare OH line) polymeric surge arresters should be used.

For vertical construction or where the insulators are not upright, the Current Limiting Arcing Horn (CLAH) arrangement should be used.

Surge arrester details:

11kV Polymeric Arrester, complete with insulated mounting bracket, galvanised steel support bracket, ground lead disconnect device, bird cap, insulated aluminium stranded phase lead and copper stranded earth lead (stockcode 150383).

11kV Current Limiting Arcing Horn (CLAH) (stockcode 144659) complete with Discharge Connector (stockcode 144667 for 120 mm2 cables, 144675 for 80 mm2 cable and 176322 for 180mm2).

Note: Arrestors should be class NS to AS 1307.2.



6.4.3 Polymeric surge arrester

Figure 1 – Polymeric Surge Arrester

Surge arresters must comply with the requirements of AS 1307.2.

Surge arresters must be compatible with the covered conductor system. The surge arrester, must be the polymeric type rather than the porcelain type, for safety and insulation integrity reasons.

The line connection cable should be connected to the CCT conductor via a Parallel Groove connection or other suitable CCT IPC as discussed in Clause 6.5.3.

Note: Polymeric surge arresters must be handled in accordance with NSA 1494.

6.4.4 Current limiting arcing horn (CLAH)

Figure 2 – Current Limiting Arcing Horn (CLAH)

The Current Limiting Arcing Horn (CLAH) is a composite surge arrester comprising an arcing horn and a current-limiting non-linear resistor in series. Under no-surge conditions the full phase voltage appears across the external air gap and the current limiting element is not electrically stressed. When an arc is produced due to a surge, the current limiting element allows the surge current to pass through the non-linear resistor to ground. As soon as the abnormal surge voltage subsides, the non-linear resistor regains its high resistance and helps extinguish the power follow arc in the arcing horn which could have otherwise continued for a longer time.



The two electrodes of the arcing horn are the discharge connector fitted on to the CCT and the horn fitted on to the current-limiting element. The air gap can be adjusted to suit the system voltage and the insulation co-ordination guidelines by using the slide mechanism of the horn. Under normal conditions a gap of 20 mm is specified for 11kV CCT lines.

The discharge connector is an ultraviolet resistant, track resistant, hinged moulding of insulating material with a thick mastic coating on the inside for waterproofing the connection. The connector has a plastic bolt with a metal pin embedded at the end. While the point of the metal pin extends out of the plastic bolt the head of the pin is located halfway inside the plastic bolt. A narrow hole extends from the head of the plastic bolt to the head of the metal pin. When the bolt is screwed in, the metal pin pierces the insulation of the CCT and contacts the conductor. The hole in the plastic bolt acts as a chute for the arc between the head of the pin and the horn during flashover. This arrangement maintains the integrity of the covered system by preventing exposure of the conductor. Also, the chute helps control the variation of the flashover voltage by providing a sheltered chamber for ionisation of air prior to flashover.

The metal oxide element used for the CLAH is similar to a polymeric arrester but is moulded in rubber, which is ultra-violet resistant, track resistant, and waterproof. The CLAH has a lower voltage rating and fault capacity than polymeric arresters.

6.4.5 Insulation co-ordination The basic insulation co-ordination principles of the following Australian Standards should be applied:

AS 1824.1 Insulation co-ordination - Definitions, principles and rules, and

AS 1824.2 Insulation coordination (phase-to-earth and phase-to-phase, above 1 kV) - Application guide.

6.5 CCT Fittings and insulating covers 6.5.1 General The covered conductor system, although not a touch-safe screened cable system, is designed to provide protection from initiation of flash-overs due to clashing of conductors, bird or animal incursions, and tree branches or debris blown or fallen on to the line. To maintain the integrity of the design criteria it is essential that all points of attachment of fittings where the covering is stripped or punctured be suitably covered. For this purpose special covers shall be installed correctly on each piece of hardware.

6.5.2 Strain clamp and cover Strain clamps for CCT lines are made of aluminium alloy and employ wedge action for easy installation on the conductor and taking the full line tension after installation. The rack and pinion mechanism and the conductor holder bolt further assist the installation of the clamp. Table 3 shows the relevant strain clamp stockcodes.

Table 3 – Strain Clamp Stockcodes

CCT Cable Strain Clamp Strain Clamp Cover

80mm² 144535 144543

120mm² 144527 144543

180mm² 176313 181248



The strain clamp cover folds over the unit and is locked together with tags. It is difficult to remove the covers after installation.

Figure 3 – Strain Clamp (shown without cover)

6.5.3 Parallel groove clamp and cover Parallel Groove (PG) clamps are used to make non-tension connections between conductors. The two cast aluminium halves of PG connectors are held together with aluminium bolts and nuts and stainless steel washers. The connectors accommodate the following range of conductor sizes:

Main conductor: 7/3.75 to 19/3.5 (CCT80, CCT120, CCT180) Tapping conductor: 7/3.75 to 19/3.5 (CCT80, CCT120, CCT180)

The stockcodes for CCT PG clamps are shown in Table 4.

Table 4 – CCT PG Clamp Stockcodes

PG Clamp PG Clamp Cover

144568 144576

The PG cover has tapered conductor entries, which are trimmed to size depending on the size of CCT conductor used.

Figure 4 – Parallel groove clamp shown without cover

Alternatives to PG clamps such as CCT insulation piercing connections (IPCs) may also be used subject to approval by Ausgrid in accordance with NS181 Approval of Materials and Equipment and Network Standard Variations.

6.5.4 Standard earthing point and cover Earthing points must be established at all points where it is envisaged that access permit earths or working earths will be required during future operations/maintenance/extension works. These locations are on either side of the switching devices and at other points nominated by Ausgrid.

Where pole mounted equipment such as reclosers requires that access permit earths or working earths be installed from an elevating work platform, they shall be placed at least one metre from the vertical projection of the nearest energised conductor. To accommodate this, the earthing point shall be established at least one metre from the dropper cable.



Such standard earthing points are created by removing 125mm of the insulation on the CCT at each nominated point. An earthing point cover shall be installed at each earthing point. The cover is moved along the conductor to reveal the earthing point by tapping with an earthing stick. The cover must be returned to its correct position after removal of the earths. Table 5 shows the stockcode for the earthing point cover.

Table 5 – Earthing Point Cover Stockcode

Earthing Point Cover

144741

Figure 5 – Earth Point Cover

Alternatives to the standard earthing points described above such as CCT insulation piercing stirrup connections may also be used subject to approval by Ausgrid in accordance with NS181.

6.5.5 Tie wires The aluminium covered steel tie-wires are preformed, left-hand lay, and coated with grey nylon. Three sizes are available, one to match each conductor size, with colour coded end caps identifying each size. Bare tie wires must not be used on CCT as they cause electrical tracking of the insulation.

Tie wire stockcodes are shown in Table 6.

Table 6 – Tie Wire Stockcodes

CCT Cable Tie Wire

80mm² 144618

120mm² 144600

180mm² 176312

6.5.6 Full tension joint Full tension joints must only be used to joint conductors that are the same size and type. When more than one phase is jointed in a span, joint positions of different phases must be offset by at least 1m. The heatshrink covering will protect the conductor but is not equivalent to the original



conductor covering and care must be taken in the placement of joints to ensure that they are not subjected to abrasion.

Table 7 – Full Tension Joint Stockcodes

CCT Cable Full Tension Joint sleeve

Mastic coated heatshrink tube

80mm² 144733 Supplied with sleeve



6.5.7 Compression lugs Compression lugs shall be as shown in Drawing No 514053.

6.6 CCT crossarms 6.6.1 Crossarm for post insulators Crossarms shall be in accordance with Ausgrid’s current specification. Refer Drawing Nos 514373 and 514374 as appropriate.

Note 1. The thread diameter of BC insulator pins is 24mm (requiring 26mm crossarm hole), whereas the thread diameter of CCT post insulators is 16mm (requiring 18mm crossarm hole). Therefore when converting BC to CCT the crossarms should also be changed, unless approved otherwise by Ausgrid, since the use of the 16mm threads in 26mm crossarm holes is not mechanically sound and can lead to crossarm fires.

Note 2. In some rural lines, with long spans where constraints such as way-leave and tree-trimming are minimal, longer crossarms may be used subject to Ausgrid approval provided the documentation demonstrating that proper clearances are maintained is submitted with the request.

6.7 Pole-top operating devices Only equipment that complies with Ausgrid’s current specification shall be used. This includes non-enclosed isolating switches, fuses and disconnectors or enclosed switches.

This equipment will be installed at intervals specified by Ausgrid.

Standard earthing points and covers shall be provided on both sides of each operating device.

6.8 Pole substations/transformers Pole transformers for CCT systems shall be in accordance with the requirements of NS122 Pole Mounted Substation Construction.

6.9 Regulators Pole mounted regulators shall be constructed in accordance with the latest amendment of Drawing No 224227.

6.10 Capacitors Pole mounted capacitors shall be constructed in accordance with the latest amendment of Drawing No 162475.

6.11 Electrical safety procedures The requirements of Ausgrid’s Electrical Safety Rules must be observed at all times when working on CCT systems. CCT does not have an insulation screen and can therefore carry dangerous voltages on the outer surface. All precautions normally taken on bare overhead lines should be



taken when working on CCT lines. Before working on a CCT line (except when using live line procedures) steps must be taken to ensure the line has been isolated, proven de-energised, short-circuited and earthed in accordance with the Ausgrid Electrical Safety Rules.

Note: Before commencing work at a worksite from which the Access Permit earths at the isolation points are not visible, the line must be positively identified as described in Clause 6.11.3.

6.11.1 Isolation and proving de-energised Isolation must be carried out in accordance with the Ausgrid Electrical Safety Rules (i.e. isolated from all possible sources of supply).

Covered conductors cannot be proven de-energised by stabbing. There is no earthed screen in the cable and stabbing must not be attempted.

Proving de-energised must be carried out with an approved HV testing device at standard earthing points, or at a termination or transition where exposed conductors are available, then tracing the line to the work site.

6.11.2 Earthing and short-circuiting For CCT lines, the earth points will normally be adjacent to the isolation points. Earthing and short-circuiting each conductor at these points of isolation satisfies the requirement for all conductors to be earthed and short-circuited between all points of isolation and the work site. These earths shall be nominated as Access Permit earths.

6.11.3 Identification After the Access Permit earths have been fitted and an Access Permit issued on the line, the line must be positively identified at the worksite. This must be done by visually tracing the line from a point of isolation to the worksite. A marker should be attached to the line using HV live line working methods.

A second person must independently verify the visual tracing. The verification must be carried out in the opposite direction - from the mark on the cable to the earth at the point of isolation.

6.12 Erection of CCT lines Poles associated with CCT overhead lines shall be erected in accordance with NS128 Specification for Pole Installation and Removal.

Poles shall be located in accordance with NS167 Positioning of Poles and Lighting Columns.

Covered conductors are to be erected using the pulling in (or tension stringing) method. The paying-out method can also be used, provided precautions are taken not to damage the CCT.

When tensioning a new conductor a suitable allowance shall be made for the initial stretch (“creep”) of the conductor.

Refer to NS220 Overhead Design Manual and AS/NZS 7000 Overhead line design - Detailed procedures for further information.

6.12.1 Precautions The following precautions shall be taken when working with CCT:

Conductor insulation must not be removed at the pin or post insulator. When pulling in cables take care not to damage the insulation. Never bend the cable tighter than the minimum bending radius. Refer to Clause 6.1. Do not drop the cable or drag it along the ground or over any obstacle. Do not let the cable rub against poles.

Where insulation is to be removed from CCT conductor, it must be removed using tools and procedures specifically designed for this purpose. The conductor MUST NOT be damaged



(nicked) during stripping. The use of incorrect tools and procedures can lead to premature failure of the conductor.

6.12.2 Angle of deviation specifications The angle of deviation specifications are provided in Table 8.

Table 8 – Angle of Deviation Specifications

Angle of Deviation Required Construction

Vertical construction 0 - 10 deviation Post insulator on bracket. (stockcode: 144626)

Vertical construction 10 - 30 deviation Post insulator on angle bracket. (stockcode: 144634)

Vertical construction > 30° deviation Strain clamp and strain rod arrangement.

Horizontal construction 0° - 25° deviation Pin post (single crossarm).

Horizontal construction 25° - 50° Pin post (double crossarm).

Horizontal construction > 50° Strain clamp and strain rod arrangement.

Delta Construction 0 - 25 deviation Post insulators on single cross arm and one pole raiser.

Delta Construction 25 - 50 deviation Post insulators on double cross arms and two pole raisers.

Delta Construction > 50 deviation Strain clamp and strain rod arrangement.

6.13 11kV UGOH constructions Underground to Overhead (UGOH) constructions shall be constructed in accordance with the requirements of:

NS177 11kV Joints (including Transition Joints) & Terminations - Polymeric Insulated Cables, or

NS129 11kV Joints and Terminations – Paper Insulated Lead Covered Cables, depending on the type of UG cable to which the overhead conductors are to be connected.

Refer to Drawing No. 160354 regarding the preferred and alternative methods of bonding the UGOH to the OH mains.

11kV UGOH must never be constructed on concrete or steel poles which also carry subtransmission (i.e. 33kV, 66kV or 132kV) mains. This is due to the transferred voltage and earth potential rise (EPR) hazards associated with faults on the subtransmission mains which may affect the 11kV mains.

6.14 Construction diagrams of covered conductor thick arrangements CCT lines shall be constructed in accordance with the latest amendment of the following standard construction drawings (see Table 9 below) as appropriate.

Note 1: Stainless steel conical (volute) washers shall be used on all bolts used to secure crossarms to a pole or equipment to a crossarm or pole. The approved method for a crossarm attached to a pole is to use a bolt fitted with a square washer, through the pole, gain block and crossarm then use 1 x square washer, 1 x SS conical washer, 1 x round washer (galv) and finally the nut.

Note 2: Equipment mounted on a crossarm similarly requires either 2 x square washers, or the steelwork substituting 1 x square washer, plus 1 x SS conical washer, 1 x round washer and a nut. Both cases require a large surface area in contact with the timber to prevent indentation. The conical washer is used to allow for shrinkage of the timber.



Table 9 – CCT Conductor Standard Construction Drawings

Description Construction Number Drawing Number

11kV Horizontal Pin Construction 2-1CCT 174956

11kV Offset Arm Construction 2-2CCT 174957

11kV ¾ Offset Arm Construction 2-4CCT 175880

11kV Small Delta Construction 2-5CCT 174958

11kV Delta Construction 2-6CCT 174959

11kV Large Delta Construction 2-7CCT 174960

11kV Termination Construction 2-10CCT 174961

11kV Through Termination Construction 2-11CCT 174962

11kV Corner Pole Termination Construction 2-12CCT 174963

11kV Tee-Off Construction 2-14CCT 174964

11kV Large Through Delta Termination Construction 2-30CCT 174965

11kV Large Delta Corner Construction 2-31CCT 174966

11kV Large Through Delta Termination with Tee-Off Construction 2-37CCT 174967

11kV Large Delta with Tee-Off Construction 2-38CCT 174968

11kV Through Termination Construction with Dropout Fuses or Isolating Links 2-60CCT 175886

11kV Tee-Off Construction with Dropout Fuses or Isolating Links 2-61CCT 175887

11kV Horizontal Pin Twin Crossarm Construction 2-101CCT 175883

11kV Delta Twin Crossarm Construction 2-106CCT 175884

11kV Large Delta Twin Crossarm Construction 2-107CCT 175885

11kV Vertical Termination Construction 2-140CCT 163265

11kV Vertical 4 Way Termination Construction 2-142CCT 175878

11kV Vertical Through Termination With Tee Off Construction 2-146CCT 163144

11kV Delta Pin Post Construction 2-200CCT 163146

11kV Vertical Pin Post Construction 2-240CCT 163145

11kV Vertical Pin Post with Tee Off Construction 2-242CCT 175876

11kV Vertical Pin Post 4 Way Crossover Construction 2-243CCT 175877

12/24kV AK Power Mid Pole Operated Air Break Switch for Timber, Concrete & Steel Poles 2-455 175902

Standard Construction 11kV CCT Surge Arrester Arrangements - 177151

Standard Construction 11kv S&C Intellirupter Pulsecloser with By-Pass Air Break Switch General Arrangement - 220251

Standard Construction 11kV S&C IntelliRupter Pulsecloser Controlling Pole Mounted Regulators 224228

Standard Construction 2 Unit 11kV Pole Mounted Regulator with Pole Mounted Control Panel 224402



Table 10 – CCT to Bare Conductor Standard Construction Drawings

Description Construction Number Drawing Number

Standard Construction 2 Unit 11kV Pole Mounted Regulator with Ground Mounted Control Panel 224401

Standard Contruction 3 Unit 11kV Pole Mounted Regulator with Ground Mounted Controllers 224229

Standard Contruction 11kV S&C IntelliRupter Pulse closer without Bypass Air Break Switch 220041

11kV CCT to Bare Conductor Through Termination Construction 2-411 154233

11kV CCT to Bare Conductor Corner Pole Termination Construction 2-412 154234

11kV Bare Conductor to CCT Tee-Off Construction 2-414 154235

11kV CCT to Bare Conductor Large Delta Through Termination Construction 2-430 154236

11kV CCT to Bare Conductor Large Delta Corner Construction 2-431 154237

11kV Bare Conductor Large Through Delta Termination with CCT Tee-Off Construction 2-437 154238

11kV Bare Conductor Large Delta with CCT Tee-Off Construction 2-438 154239

11kV CCT to Bare Conductor Vertical Termination Construction 2-4140 177229

CCT Fittings: Overhead Line Compression Fittings Index

514053



Details of Bare Conductor Arrangements

6.15 General details The conductor used for Bare Conductor (BC) HV overhead lines shall be manufactured to comply with the relevant Australian Standard from the following list.

AS 1222 Steel conductors and stays – Bare overhead AS 1531 Conductors – Bare overhead, Aluminium and aluminium alloy AS 1746 Conductors – Bare overhead – Hard-drawn copper AS 3607 Conductors – Bare overhead, Aluminium and aluminium alloy – Steel reinforced

The conductors listed in Table 11 are commonly used by Ausgrid.

Table 11 – Electrical and Mechanical Characteristics

Conductor Mercury Pluto Apple Cherry

Stockcode H13433 H13459 H13467 H13483

Number of strands/wire diameter 7/4.50 19/3.75 6/1/3.00 6/4.74 + 7/1.6

Alloy type/grade AAC AAC ACSR/GZ ACSR/GZ

Cross sectional area (mm2) 111.3 209.8 49.5 120.4

Minimum breaking load (kN) 16.8 32.3 14.9 33.2

DC resistance at 20°C (Ω/km) 0.258 0.137 0.677 0.271

Diameter of conductor (mm) (approx) 13.5 18.8 9.0 14.3

Mass (kg/m) (approx.) 0.305 0.578 0.171 0.404

Current rating Refer NS 220 Section 7.

Modulus of elasticity (GPa) 56 56 79 76

Co-efficient of linear expansion (/°C x 10-6) 23 23 19.3 19.9

Other conductors are also used under certain circumstances.

Where bare conductor is used, specific effort must be made during design and construction activities to avoid any possibility of conductor clashing throughout the life of the overhead line.

For this reason delta (small) is the preferred construction for all intermediate structures. Flat pin construction shall be used only when under-building the circuit or for under-crossing structures. For longer spans, delta (medium) and large delta constructions are available and other construction types (e.g. horizontal offset, etc) may be used under specific circumstances and subject to approval of Ausgrid. Details of approved designs for such construction types may be obtained by contacting Ausgrid.

6.16 Bare conductor line design BC lines shall generally be designed in accordance with Section 9. In addition, the following requirements shall be observed.

6.16.1 Phasing The configuration of phases shall be according to the particular installation requirements as specified by Ausgrid. Where there are no installation constraints, the following configuration shall be used:

Phase A: Bottom conductor or footpath / property side Phase B: Centre conductor



Phase C: Top conductor or road side.

6.16.2 Clearances and spacings of bare conductors 6.16.2.1 Phase-to-phase spacing for BC For new construction the minimum phase-to-phase spacing between conductors should be in accordance with AS/NZS 7000 Overhead line design - Detailed procedures.

In the case of horizontal construction, crossarms on alternate poles with flat pin construction should be fitted with reverse orientation to achieve improved mid-span clearance (ie. the centre conductor alternates from one side of the pole to the other).

6.16.2.2 Separation between Bare Conductors (BC) and Low Voltage (LV) Aerial Bundled Cable (ABC) or LV BC

The separation between the BC and LV ABC or LV bare conductors at the pole construction depends on whether the HV network can be worked on using live line techniques. Refer to NS 220 Overhead Design Manual - Section 10 for live-line circuit to circuit clearances. Midspan separation must not be less than that specified in AS7000.

Spur lines should always be designed and constructed with live-line circuit to circuit separations.

For further live-line design principles refer to NS214 Guide to Live Line Design Principles.

6.16.2.3 Clearances to ground, structures and vegetation The clearance of BC to ground, structures and vegetation shall be in accordance with Section 11.

6.16.3 Vibration dampers Appropriate vibration dampers shall be installed as required by AS/NZS 7000 for the conductor tension.

6.17 Insulators The insulators used for all 11kV and 22kV BC mains shall be 22kV rated.

6.17.1 Through constructions Pins shall be type C/200/11 and manufactured in accordance with AS 1154 Insulator and conductor fittings for overhead power lines.

Identification numbers of pin and pin threads shall be stamped on the pin collar (C/200/11) indicating the following:

C = thread pattern on head

200 = stem length in mm

11 = failing load in kN

Finish shall be hot dip galvanised.

Insulators shall be 22kV, type ALP 22/450 and manufactured in accordance with AS/NZS 2947 Insulators - Porcelain and glass for overhead power lines - Voltages greater than 1000 V a.c. - Test methods.

Colour: light grey.

Refer Drawing No 513997.

6.17.2 Termination constructions All bare conductor constructions shall use polymeric longrod insulators. They shall be in accordance with Ausgrid’s current insulator specification. Refer to Drawing No. 565715.



Note: Polymeric insulators must be handled in accordance with NSA 1494 Polymeric Insulator Handling Guide.

6.18 Lightning protection Surge diverters shall be 10kA polymeric in accordance with Ausgrid’s current specification.

Surge diverters shall be located at all pole substations, enclosed load break switches, reclosers and UGOH connections.

Surge diverters shall be earthed in accordance with NS116 Design Standards for Distribution Earthing and shall be designed and constructed in accordance with the relevant drawings listed in Clauses 6.14 and 7.13.

The earth leads on S&C IntelliRupters shall be designed and constructed in accordance with the relevant drawings listed in Clauses 6.14 and 7.13.

Note: Polymeric surge arresters must be handled in accordance with NSA 1494.

6.19 BC Fittings 6.19.1 Parallel Groove (PG) clamp PG clamps shall comply with the requirements of AS 1154.1.

6.19.2 Full tension sleeve Full tension sleeves shall comply with the requirements of AS 1154.1. Full tension sleeves shall be installed in accordance with the manufacturer’s instructions particularly with regard to the tooling used (eg. versa crimp or hexagonal die) and number of crimps. Stockcodes and other details for suitable full tension sleeves are shown on Drawing No. 514053.

The die size, and number and location of crimps should be marked on the sleeve. If not, they shall be returned to the store for return to the supplier.

6.19.3 Non-tension sleeve Non-tension sleeve shall comply with the requirements of AS 1154.1. Non-tension sleeves shall be installed in accordance with the manufacturer’s instructions particularly with regard to the tooling used (e.g. versa crimp or hexagonal die) and number of crimps. Stockcodes and other details for suitable non-tension sleeves are shown on Drawing No. 514053.

6.19.4 Spiral vibration damper Spiral vibration dampers shall comply with the relevant sections/parts of AS 1154.

6.19.5 Armour rod Helical fittings such as armour rods shall comply with the requirements of AS 1154.3.

6.19.6 Compression lugs Compression lugs shall comply with the requirements of AS 1154.1. Compression lugs shall be installed in accordance with the manufacturer’s instructions, particularly with regard to the tooling used (e.g. versa crimp or hexagonal die) and number of crimps. Stockcodes and other details for suitable compression lugs are shown on Drawing No. 514053.

6.19.7 Preformed dead-end Helical fittings such as pre-formed dead-ends shall comply with the requirements of AS 1154.3.

6.19.8 Tie wire Tie wire shall be 5mm diameter annealed aluminium or copper to suit the conductor used.



6.19.9 Joint compound Joint compound used with aluminium connections shall seal out air and moisture, minimising oxidation or corrosion and maximising conductivity. In certain applications it shall contain conductive (zinc) particles within the compound to penetrate oxide films that form on the aluminium surfaces.

6.20 Crossarms Crossarms shall be in accordance with Ausgrid’s current specification. Refer to Drawing Nos 514373 and 514374 as appropriate.

6.21 Pole-top operating devices 6.21.1 Air break switches Air Break Switches (ABS) shall be load break type complying with Ausgrid’s current specification. ABSs and their operating mechanisms shall be installed such that no pole attachments or earthing conductors are less than 3.6m above ground level. Wherever practical, when installed on a pole next to a road, the operating mechanism shall be installed such that the ABS can be operated by the operator standing on the side of the pole away from the road.

All ABSs shall be mounted on poles in accordance with the latest amendment of Drawing No. 175902.

6.21.2 Pole mounted circuit breakers (reclosers) Pole mounted circuit breakers for use on 11kV mains shall be 12kV 400A three phase, outdoor, pole mounted, automatic, Circuit reclosers, complying with Ausgrid’s current specification.

All pole mounted circuit breakers shall be mounted on poles in accordance with the latest amendment of Drawing Nos. 127318, 220041 or 220251 as appropriate.

6.21.3 Under-slung links Under-slung links shall comply with Ausgrid’s current specification.

6.21.4 Drop-out fuses Drop-out fuses shall comply with Ausgrid’s current specifications.

Three types of 11kV drop-out fuses are currently used, depending on the fault level, as shown in Table 12 below. Where necessary, fault level shall be specified in the Design Information. Fuse ratings shall be in accordance with TS4200 Fuse Standard.

Table – 12 11kV Drop-out Fuses

Fault Level Fuse Base & Carrier Type

Up to 8kA Fuse base and expulsion fuse link in accordance with Ausgrid’s current specification (Stockcode: H84350 )

8kA – 11.2kA S & C 25kV SMD-20 fuse base and boric acid fuse link (Stockcode H70029).

>11.2kA Refer to Distribution Automation & Substation Engineering for advice.

6.21.5 Enclosed load break switches Enclosed load break switches shall comply with Ausgrid’s current specification.

6.22 Pole substations/transformers BC pole substations shall be in accordance with the requirements of NS122 Pole Mounted Substation Construction.



6.23 Regulators Pole mounted regulators shall be constructed in accordance with the latest amendments of Drawing No 224227.

6.24 Capacitors Pole mounted capacitors shall be constructed in accordance with the latest amendment of Drawing No. 162475.

6.25 Erection of BC lines Poles associated with BC overhead lines shall be erected in accordance NS128 Specification for Pole Installation and Removal.

Poles shall be located in accordance with NS167 Positioning of Poles and Lighting Columns.

The two principle methods of erection are paying-out and pulling-in. Of the two, pulling-in is the preferred method as it minimises the likelihood of damage to the conductor during the installation process.

When tensioning a new conductor a suitable allowance shall be made for the initial stretch (“creep”) of the conductor.

Refer to NS 220 and AS/NZS 7000 for further information.

6.26 11kV UGOH constructions Underground to Overhead (UGOH) constructions shall be constructed in accordance with the requirements of:

NS177 11kV Joints (including Transition Joints) & Terminations - Polymeric Insulated Cables, or

NS129 11kV Joints and Terminations – Paper Insulated Lead Covered Cables, depending on the type of UG cable to which the overhead conductors are to be connected.

Refer to Drawing No. 160354 regarding the preferred and alternative methods of bonding the UGOH to the OH mains.

11kV UGOH must never be constructed on concrete or steel poles which also carry subtransmission (i.e. 33kV, 66kV or 132kV) mains. This is due to the transferred voltage and earth potential rise (EPR) hazards associated with faults on the subtransmission mains which may affect the 11kV mains.

6.27 Construction diagrams of BC arrangements BC lines shall be constructed in accordance with the latest amendment of the following standard construction drawings (see Table 13 below) as appropriate.

Note 1: Stainless steel conical (volute) washers shall be used on all bolts used to secure crossarms to a pole or equipment to a crossarm or pole. The approved method for a crossarm attached to a pole is to use a bolt fitted with a square washer, through the pole, gain block and crossarm then use 1 x square washer, 1 x SS conical washer, 1 x round washer (galv) and finally the nut.

Note 2: Equipment mounted on a crossarm similarly requires either 2 x square washers, or the steelwork substituting one square washer, plus 1 x SS conical washer, 1 x round washer and a nut. Both cases require a large surface area in contact with the timber to prevent indentation. The conical washer is used to allow for shrinkage of the timber.



Table 13 – BC Lines Standard Construction Drawings

Description Construction Number

Drawing Number

11kV Constructions 11kV Flat Pin Construction (see note 2 below) 2-1 513909 11kV Offset Arm Construction 2-2 513910 11kV Angle Suspension Construction 2-3 513911 11kV ¾ Offset Arm Construction 2-4 175879 11kV Small Delta Construction (see note 1 below) 2-5 513912 11kV Delta Pin Construction (see note 3 below) 2-6 520222 11kV Large Delta Pin Construction (see note 3 below) 2-7 513913 11kV Termination Construction 2-10 513914 11kV Through Termination Construction 2-11 513915 11kV Corner Pole Termination 2-12 513916 11kV Tee-off Construction 2-14 513917 11kV Railway Termination RHS Galv. Crossarm 2-23 513918 11kV Large Through Delta Termination Construction 2-30 513919 11kV Large Delta Corner Construction (see note 3 below) 2-31 513943 11kV Large Through Delta Termination with tee-off construction (see note 3. below)

2-37 514180

11kV Large Delta with tee-off construction (see note 3 below) 2-38 520410 11kV Through Termination Construction with Drop-out Fuses or Isolating Links

2-60 514007

11kV Tee-Off Construction with Drop-out Fuses or Isolating Links 2-61 513895 11kV Vertical Delta Construction 2-200 183908 11kV Vertical Construction 2-240 183907 12/24kV AK Power Mid Pole Operated Air Break Switch for Timber, Concrete & Steel Poles

2-455 175902

Standard Construction 11kv S&C Intellirupter Pulsecloser with By-Pass Air Break Switch General Arrangement

- 220251

11kV Pole Top Capacitors Construction Detail 162475 Standard Construction 11kV S&C IntelliRupter Pulsecloser Controlling Pole Mounted Regulators

224228

Standard Construction 2 Unit 11kV Pole Mounted Regulator with Pole Mounted Control Panel

224402

Standard Construction 2 Unit 11kV Pole Mounted Regulator with Ground Mounted Control Panel

224401

Standard Construction 3 unit 11kV Pole Mounted Regulator with Ground Mounted Controllers

224229

Standard Construction Pole Top Regulator Ground mounted Fibreglass Cabinet Concrete Footing Details

191227

Standard Construction 11kV S&C IntelliRupter Pulsecloser without Bypass Air Break Switch

220041

Standard Construction 11kV Underground to Overhead Construction Details

160354

Standard Construction 11kV Pole Mounted Regulator with Controlling IntelliRupter

224227

22kV Constructions 22kV Horizontal Pin Construction 3-1 513993



Description Construction Number

Drawing Number

22kV Small Delta Construction 3-5 513994 22kV Termination Construction 3-10 513991 22kV Through Termination Construction 3-11 513992 22kV Vertical Termination Construction 3-140 184959 22kV Vertical Delta Construction 3-200 184958 22kV Vertical Construction 3-240 184957 Pole Substations BC Pole Substation Construction Arrangement - Refer NS122 BC Fittings Overhead Line Compression Fittings Index 514053 Standard Construction 11/22kV Aerodynamic Insulator and Pin Arrangement

513997

Notes:

1. Construction 2-5 is the preferred construction for all intermediate structures in urban areas.

2. Construction 2-1 is to be used only when under-building the circuit or for under-crossing structures.

3. Constructions 2-6, 2-7, 2-31, 2-37, 2-38 are for use with longer spans only.



7.0 SINGLE WIRE EARTH RETURN (SWER) 7.1 General

7.1.1 Distribution systems Single Wire Earth Return (SWER) distribution systems utilise a single overhead wire, with the return path through the earth. SWER systems are less expensive and easier to construct and maintain than three phase systems, and are typically used to supply relatively small loads which are long distances from normal 3 phase supply systems in rural areas, etc.

Figure 6 – Typical SWER System

Power is supplied to the SWER line by a single isolating/step-up transformer that changes the grid voltage (11 kV) to the SWER voltage (12.7 kV), Each customer generally has their own small-capacity single-phase substation. At the substation, current flows from the line, through the primary coil of a step-down transformer, to earth through an earth stake. From the earth stake, the current flows through the earth, back to the main isolating transformer at the beginning of the line, completing the circuit. The secondary winding of the transformer typically supplies the customer with 240-0 volts or 240-0-240 volts, with the 0 volt line connected to a safety earth.

7.1.2 Advantages SWER systems have a number of advantages. SWER lines utilise the same components as normal 3-wire/3-phase or 2 wire/1 phase BC systems. SWER systems are quicker to build and have lower construction costs compared to the normal 3-wire/3-phase or 2 wire/1 phase systems, through the use of one wire instead of three or two, and also because of the reduced quantities of pole fittings (crossarms, insulators, etc.). Similarly SWER systems can have lower maintenance costs due to the fewer components involved. SWER systems can also reduce the risk of initiating bushfires because conductor clashing cannot occur in high winds.

7.1.3 Disadvantages SWER systems also have a number of disadvantages. SWER lines typically have a “spur” (linear) layout with no alternative means of supply and therefore a single-point failure can cause lengthy interruptions to supply to all customers further down the line. Since SWER lines tend to be long, the voltage drop along the line is often a problem, causing poor power quality. Also, significant earth return currents flowing through the ground near the customer substations can pose a safety risk, and particular care must therefore be taken to ensure good, low impedance, earth connections.

7.1.4 Use SWER systems shall be used only under specific circumstances and subject to the approval of Ausgrid.



7.2 SWER line design SWER lines shall generally be designed in accordance with Section 9; in addition to the requirements relating to conductors, design considerations, vibration dampers, insulators, lightning protection and fittings detailed for Bare Conductors elsewhere in this Network Standard.

7.3 SWER substations SWER Isolating transformers and substations shall be in accordance with NS122 Pole Mounted Substation Construction.

7.4 Construction diagrams of SWER arrangements SWER lines shall be constructed in accordance with the latest amendment of the following standard construction drawings (see Table 14 below) as appropriate.

Note 1: Stainless steel conical (volut