Technical Note – TN 006: 2019 - Transport for NSW...If you use this document or rely upon it...

Technical Note – TN 006: 2019


Subject: Clarification of substation fencing requirements where existing locations are modified

Issue date: 13 May 2019

Effective date: 13 May 2019

For queries regarding this document [email protected]

www.transport.nsw.gov.au

This technical note is issued by the Asset Standards Authority (ASA) to notify an update to

T HR EL 99004 ST Substation Fencing, version 1.0 to clarify the substation fencing requirements

where existing locations are required to be modified and repaired.

Delete Section 6.2 in its entirety and replace with the following:

6.2 Existing locations Existing fences that do not comply with current design requirements shall be upgraded when the

fence is due for renewal, or when enhancement is required as determined by a risk assessment.

6.2.1 Modifications Where existing fences are to be modified, the design and construction of the modifications shall

be such that the resultant fence configuration shall comply with this document. Where it is not

reasonably practicable to do so, the designer shall list all noncompliances and the proposed

design approach to mitigate the risks associated with each of the listed noncompliances.

Acceptance of the mitigation measures by the relevant authority of the operations and

maintenance AEO is required prior to the commencement of detailed design. If the design and

construction of the modified fence provides a security outcome that is equivalent or better than

the existing fence configuration and is accepted by the relevant authority of the operations and

maintenance AEO, then a concession is not required for the noncompliance.

6.2.2 Repairs Repairs to the existing fences shall comply with Section 11 of T HR CI 12160 ST, version 1.0.

© State of NSW through Transport for NSW 2019 of 2


Authorisation:

Technical content prepared by

Checked and approved by

Interdisciplinary coordination checked by

Authorised for release

Signature

Date

Name Rukshan Guruge Terry Niemeier Peter McGregor Jagath Peiris

Position Senior Engineer Substations and HV Network

Lead Electrical Engineer

A/Chief Engineer A/Director Network Standards and Services

© State of NSW through Transport for NSW 2019 of 2

Substation Fencing

T HR EL 99004 ST

Standard

Version 1.0

Issued date: 16 November 2017

© State of NSW through Transport for NSW 2017

T HR EL 99004 ST Substation Fencing

Version 1.0 Issued date: 16 November 2017

Important message

This document is one of a set of standards developed solely and specifically for use on Transport Assets (as defined in the Asset Standards Authority Charter). It is not suitable for any other purpose. The copyright and any other intellectual property in this document will at all times remain the property of the State of New South Wales (Transport for NSW). You must not use or adapt this document or rely upon it in any way unless you are providing products or services to a NSW Government agency and that agency has expressly authorised you in writing to do so. If this document forms part of a contract with, or is a condition of approval by a NSW Government agency, use of the document is subject to the terms of the contract or approval. To be clear, the content of this document is not licensed under any Creative Commons Licence. This document may contain third party material. The inclusion of third party material is for illustrative purposes only and does not represent an endorsement by NSW Government of any third party product or service. If you use this document or rely upon it without authorisation under these terms, the State of New South Wales (including Transport for NSW) and its personnel does not accept any liability to you or any other person for any loss, damage, costs and expenses that you or anyone else may suffer or incur from your use and reliance on the content contained in this document. Users should exercise their own skill and care in the use of the document. This document may not be current and is uncontrolled when printed or downloaded. Standards may be accessed from the Asset Standards Authority website at www.asa.transport.nsw.gov.au




Standard governance

Owner: Lead Electrical Engineer, Asset Standards Authority

Authoriser: Chief Engineer, Asset Standards Authority

Approver: Executive Director, Asset Standards Authority on behalf of the ASA Configuration Control Board

Document history

Version Summary of changes

1.0 First issue

For queries regarding this document, please email the ASA at [email protected] or visit www.asa.transport.nsw.gov.au




Preface The Asset Standards Authority (ASA) is a key strategic branch of Transport for NSW (TfNSW).

As the network design and standards authority for NSW Transport Assets, as specified in the

ASA Charter, the ASA identifies, selects, develops, publishes, maintains and controls a suite of

requirements documents on behalf of TfNSW, the asset owner.

The ASA deploys TfNSW requirements for asset and safety assurance by creating and

managing TfNSW's governance models, documents and processes. To achieve this, the ASA

focuses on four primary tasks:

• publishing and managing TfNSW's process and requirements documents including TfNSW

plans, standards, manuals and guides

• deploying TfNSW's Authorised Engineering Organisation (AEO) framework

• continuously improving TfNSW’s Asset Management Framework

• collaborating with the Transport cluster and industry through open engagement

The AEO framework authorises engineering organisations to supply and provide asset related

products and services to TfNSW. It works to assure the safety, quality and fitness for purpose of

those products and services over the asset's whole-of-life. AEOs are expected to demonstrate

how they have applied the requirements of ASA documents, including TfNSW plans, standards

and guides, when delivering assets and related services for TfNSW.

Compliance with ASA requirements by itself is not sufficient to ensure satisfactory outcomes for

NSW Transport Assets. The ASA expects that professional judgement be used by competent

personnel when using ASA requirements to produce those outcomes.

About this document

This standard specifies the requirements for the construction of fences associated with

substations within the Transport for NSW heavy rail network.

This standard supersedes RailCorp standard EP 99 00 00 07 SP Substation Fencing,

version 3.1. The changes to previous content include:

• updates to reflect organisational changes and resulting changes in responsibilities

• conversion of the standard to ASA numbering, format, and style

• alignment with the Energy Networks Australia (ENA) Guidelines

• inclusion of guidance for boundary and internal enclosure fences

• minor amendments and clarification to content

This standard is a first issue.

© State of NSW through Transport for NSW 2017 Page 4 of 23



Table of contents 1. Introduction .............................................................................................................................................. 7

2. Purpose .................................................................................................................................................... 7 2.1. Scope ..................................................................................................................................................... 7 2.2. Application ............................................................................................................................................. 7

3. Reference documents ............................................................................................................................. 8

4. Terms and definitions ............................................................................................................................. 9

5. Fence types .............................................................................................................................................. 9 5.1. Boundary fence ...................................................................................................................................... 9 5.2. Intruder resistant fence ........................................................................................................................ 10 5.3. Internal enclosure fence ...................................................................................................................... 10

6. Design requirements ............................................................................................................................. 10 6.1. General ................................................................................................................................................ 10 6.2. Existing locations ................................................................................................................................. 11 6.3. Boundary fence .................................................................................................................................... 11 6.4. Intruder resistant fence ........................................................................................................................ 12 6.5. Internal enclosure fence ...................................................................................................................... 12 6.6. Welded mesh fence construction ........................................................................................................ 12 6.7. Alternative fencing materials................................................................................................................ 13 6.8. Toppings .............................................................................................................................................. 13 6.9. Kerbing ................................................................................................................................................. 13 6.10. Ground level and fence height ......................................................................................................... 14 6.11. Climbing aids ................................................................................................................................... 14 6.12. Gates ............................................................................................................................................... 15 6.13. Clearance zone ................................................................................................................................ 17 6.14. Vegetation ........................................................................................................................................ 17

7. Electrical clearance ............................................................................................................................... 17 7.1. Non-penetrable panel .......................................................................................................................... 18

8. Substation fence earthing, bonding and isolation ............................................................................. 18 8.1. Earthing and bonding ........................................................................................................................... 18 8.2. Isolation and transfer potential mitigation ............................................................................................ 18 8.3. Testing and measurement ................................................................................................................... 19

9. Signage ................................................................................................................................................... 19

10. Construction factors ............................................................................................................................. 20

11. Maintenance ........................................................................................................................................... 20

Appendix A Additional references and drawings ................................................................................ 21 A.1. Documents ........................................................................................................................................... 21 A.2. Drawings .............................................................................................................................................. 21

Appendix B Substation fencing examples ........................................................................................... 22 B.1. Traction SS, section hut, or system SS – Indoor HV switchgear ........................................................ 22 © State of NSW through Transport for NSW 2017 Page 5 of 23



B.2. Traction SS or system SS – Outdoor HV switchgear and exposed busbars ...................................... 22 B.3. 1500 V link or switch enclosure (free standing) ................................................................................... 23




1. Introduction Unauthorised access to electricity infrastructure is considered to have a high-risk profile due to

the consequences of receiving an electric shock. Fences are one of the primary means of

limiting access to outdoor electrical installations at ground level, such as high voltage

substations.

2. Purpose The purpose of this standard is to provide requirements and guidance to ensure that fencing

associated with substations, sectioning huts and distribution substations in the RailCorp

distribution network or traction system is constructed properly and is fit for purpose.

This standard is based on ENA DOC 015 – 2006 National Guidelines for Prevention of

Unauthorised Access to Electricity Infrastructure.

2.1. Scope This standard specifies the requirements for the construction of fences associated with

substations within the Transport for NSW heavy rail network.

It defines the following three types of fencing for use in limiting access to persons:

• boundary

• intruder resistant

• internal enclosure

2.2. Application This standard is intended to be used by competent personnel engaged in the provision of

services relating to rail infrastructure. If, when using the standard, it is considered that the intent

of stated requirements is not clear, a clarification should be sought from the ASA Lead Electrical

Engineer.

In this standard, substation includes a substation, traction substation, transformer room, switch

room, sectioning hut, 1500 V link or switch area, containing either high voltage or 1500 V

electrical equipment.

This standard is applicable for all new substations associated with the heavy rail system in

NSW. It is not applicable to pole or pad mounted substations unless a risk assessment

determines that fencing is required. For existing locations, refer to Section 6.2.




Where a new location or modification to an existing location is constructed and energised in

stages, the risk of unauthorised access to the site and to exposed electrical equipment shall be

managed.

3. Reference documents The following documents are cited in the text. For dated references, only the cited edition

applies. For undated references, the latest edition of the referenced document applies.

Australian standards

AS 2067:2016 Substations and high voltage installations exceeding 1 kV a.c.

AS 3600 Concrete Structures

AS/NZS 4680:2006 Hot-dip galvanized (zinc) coatings on fabricated ferrous articles

AS/NZS 4792:2006 Hot-dip galvanized (zinc) coatings on ferrous hollow sections, applied by a

continuous or a specialized process

Transport for NSW standards

EP 12 10 00 10 SP System Substation Earthing

RSS-003 Railcorp Security Standard – Substations (available on request from

www.asa.transport.nsw.gov.au)

SPC 511 Boundary Fences

T HR CI 12160 ST Boundary Fences, version 1.0

T HR EL 99002 ST Substations Minimum Construction Standard

T HR EL 00006 ST Electrical Power System Signage

T MU MD 00009 ST AEO Authorisation Requirements

T MU MD 00011 ST Concessions to ASA Requirements

Transport for NSW drawings

EL 0450708 Substations Fencing - Typical Construction - Arrangement - Sheet 1



EL 0450711 Substations Fencing - Typical Construction - Details - Sheet 4

EL 0450712 Substations Fencing - Clearances to Climbing Aids - Details - Sheet 5

EL 0450713 Substations Fencing - Non Penetrable Panel - Arrangement - Sheet 6

EL 0455333 Substations Fencing - Typical Construction - Emergency Egress Gate




Other reference documents

ENA DOC 015 – 2006 National Guidelines for Prevention of Unauthorised Access to Electricity

Infrastructure

4. Terms and definitions The following terms and definitions apply in this document:

AEO Authorised Engineering Organisation

ASA Asset Standards Authority

ENA Energy Networks Australia

HV high voltage

SS substation

Note: This standard applies to specific substation types, see Section 2.2

TfNSW Transport for NSW

5. Fence types ENA DOC 015-2006 National Guidelines for Prevention of Unauthorised Access to Electricity

Infrastructure nominates different requirements for fencing depending on the purpose of the

fencing at a location.

Fencing associated with substations can be classified into the following three groups as

illustrated in Figure 5.1 of ENA DOC 015-2016:

• boundary fence

• intruder resistant fence

• internal enclosure fence

Note: TfNSW installations do not typically employ a sterile zone or sterile zone fence.

However, RSS-003 Railcorp Security Standard – Substations, may require a sterile

zone to be included in the design for Category 1 and Category 2 substations.

5.1. Boundary fence A substation boundary fence performs the following functions:

• identifies the substation site boundary

• limit the access of persons and vehicles to the site




5.2. Intruder resistant fence An intruder resistant fence is designed to limit the opportunity for intruders to climb over,

through or pass under the fence without the aid of tools. They are typically used to prevent

access to outdoor switchyards where live exposed conductors are present, or at higher risk

locations where a security risk assessment determines the requirement of such a fence.

5.3. Internal enclosure fence An internal enclosure fence is used to prevent unintended access to exposed electrical

equipment at or close to ground level within substation switchyards. For example, internal

enclosure fencing could be used around capacitor banks, auxiliary supply transformers and

voltage transformer.

An internal enclosure fence shall always be inside an intruder resistant fence.

Note: An internal enclosure fence is also referred to as a high voltage (HV) equipment

enclosure or cage in ENA DOC 015-2016.

6. Design requirements 6.1. General

All substation fences shall be designed in accordance with T HR CI 12160 ST Boundary

Fences, version 1.0 and any additional requirements detailed in this standard.

All sites, existing and new, shall be assessed prior to the design. This assessment may

influence the fence type, and the design shall ensure that the fence provides the appropriate

level of security, and shall maintain a safe working environment. Refer to T HR EL 99002 ST

Substations Minimum Construction Standard for general substation security considerations.

The Authorised Engineering Organisation (AEO) shall ensure that consultation takes place with

appropriate TfNSW stakeholders, such as operators, maintainers and the TfNSW area

responsible for security and emergency management.

The design life of fences shall be a minimum of 20 years.

All substations are considered high-risk and shall have boundary fencing, irrespective of the

rate of crime or antisocial behaviour a particular location might experience.

Note: An existing corridor or boundary fence that complies with this standard may be

utilised as the substation boundary fence, subject to a site-specific risk assessment.

Substation buildings may form part or a whole of the boundary fence or intruder resistant fence

on the basis of a risk assessment by the AEO. The risk assessment shall address whether the

building requires a higher security rating for the doors, windows, security systems, and so forth.




If the building is to form part of the fence, then the exterior of the building shall be of a

construction that minimises hand and foot holds.

An intruder resistant fence is not required if there is a building with no external electrical

equipment, and if the risk assessment by the AEO determines the building as being adequately

secure.

All substation fences shall be designed such that any structures or fixtures that might aid a

person climbing the fence are positioned clear of the fence. The minimum climbing aid

clearance shall be 3 m on both sides. If this is not achievable then refer to Section 6.11.

All fences performing the function of a boundary fence shall have a pedestrian gate and double

vehicular gates. These gates should be positioned so that access to the substation does not

require access via the rail corridor. The vehicular gates shall be internally accessed via the

pedestrian gate. All intruder resistant fences and internal enclosure fences shall have gates

appropriate for the enclosure and the equipment contained.

Fencing elements that are required to be galvanised by this standard shall comply with either

AS/NZS 4680:2006 Hot-dip galvanized (zinc) coatings on fabricated ferrous articles or

AS/NZS 4792:2006 Hot-dip galvanized (zinc) coatings on ferrous hollow sections, applied by a

continuous or a specialized process.

6.2. Existing locations Where existing locations are to be modified, the design and construction of the modification

shall be such that the resultant configuration of the whole location shall comply with this

standard. Where it is not practicable to do so, the designer shall list all noncompliances and

identify the associated hazards with a hazard log. The designer shall propose a design

approach to mitigate the risk of unauthorised access, as well as other risks, associated with the

noncompliance. The mitigation measures shall be accepted by the relevant AEO prior to the

commencement of detailed design, and be in accordance with the AEO’s judgement of

significance (JOS) processes for substations. Refer to T MU MD 00009 ST AEO Authorisation

Requirements. Where the AEO has not established a JOS process for substations that has

been accepted by the Lead Electrical Engineer ASA, the proposed design shall be documented

through a standards concession, in accordance with T MU MD 00011 ST Concessions to ASA

Requirements.

6.3. Boundary fence Boundary fences that do not perform the function of an intruder resistant fence shall be a

'security fence' as specified in Section 8.5 of T HR CI 12160 ST, version 1.0, and any additional

requirements detailed in this standard shall also apply. The preferred arrangement is the close

spaced welded mesh type.




6.4. Intruder resistant fence Intruder resistant fences shall have the same configurations as a 'high security fence' as

specified in Section 8.6 of T HR CI 12160 ST, version 1.0, and shall also meet the additional

requirements detailed in this standard.

As a minimum, 2400 mm high close spaced welded mesh with 600 mm concertina short barbed

tape shall be utilised.

Note: Toppings are required for intruder resistant fences in accordance with

Section 6.7 of ENA DOC 015-2016.

In accordance with ENA DOC 015-2016, ASA prefers that the intruder resistant fence to be

constructed as a separate fence inside the boundary fence. This is to provide a higher level of

protection by restricting vehicle access to the intruder resistant fence. The minimum distance

between the two fences shall be 3 m.

Where site conditions preclude the use of two fences, the boundary fence shall be designed

and constructed as an intruder resistant fence. In this situation, traffic barriers or bollards shall

be used as appropriate to restrict vehicle access.

6.5. Internal enclosure fence For internal enclosure fence requirements, refer to AS 2067:2016 Substations and high voltage

installations exceeding 1 kV a.c.

Note: Typically, an internal enclosure fence should be an 'urban fence' as specified in

Section 8.3 of T HR CI 12160 ST, version 1.0, utilising the top and bottom rail

configuration.

6.6. Welded mesh fence construction The close spaced welded mesh shall be galvanised and powder coated prior to installation in

accordance with SPC 511 Boundary Fences. The preferred colour is black.

The welded mesh fence shall be a single layer mesh fence. The orientation of the mesh shall be

such that the horizontal mesh aperture is larger than the vertical mesh aperture as outlined in

ENA DOC 015-2016.

The construction of the welded mesh type fence shall be as follows:

• Plumb, level, and true to design position.

• The mesh shall be under tension or ensure there are no slack sections. If there are slack

sections, then a mid-rail shall be installed and fixed.

• A straining post shall be installed for each end, corner, change of direction, and acute

variation in the level of the fence. For straight runs, there shall be a straining post every © State of NSW through Transport for NSW 2017 Page 12 of 23



50 m minimum. Each straining post shall be supported by a brace in each direction of the

fence line.

• Mesh-to-mesh and mesh-to-post joins shall be with galvanised tamper resistant or locking

nuts and bolts.

• Mesh-to-mesh joins (if any) shall overlap a minimum of 200 mm. Each overlap shall have a

securing every 100 mm horizontally and 300 mm vertically.

• Any metal exposed during construction shall be coated with a two-part epoxy corrosion

inhibitor.

Refer to EL 0450708 Substations Fencing Sheet 1 Typical Construction for a typical installation

of welded mesh type fence.

6.7. Alternative fencing materials Any substation fencing design using masonry or cladding types of fencing is not preferred and

requires approval during the design phase by the Lead Electrical Engineer, ASA.

Any substation fencing design, that does not use open mesh construction shall require further

electronic intruder detection methods due to restricted visibility of the substation premises.

Metal or timber cladding may be proposed to address local aesthetic issues. The cladding

would typically be affixed to a mesh fence that complies with this standard.

6.8. Toppings Topping of concertina short-barbed tape shall be used on intruder resistant fences in

accordance with Section 8.6 of T HR CI 12160 ST, version 1.0.

The topping shall be straight up and supported by the fence posts. A stainless steel support

wire should also be installed to maintain the integrity of the barbed tape coils.

Where local conditions determine that the concertina short barbed tape cannot be installed, the

alternate topping and fence requires approval during the design phase by the Lead Electrical

Engineer, ASA and the TfNSW area responsible for security and emergency management.

Note: 'Croc top' or similar fence toppings do not meet the requirements of

ENA DOC 015-2016 for intruder resistant fences; however, they may be used as an

additional deterrent for boundary fences.

6.9. Kerbing Kerbs shall be included in the design of the fence. Kerbs prevent the integrity of the fence being

compromised due to subsidence, erosion, and burrowing. Kerbs are also known as ‘plinths’ or

‘anti-dig footings’.




Typically, the kerb centre-line shall be directly below the fence line, with the bottom of the fence

no more than 50 mm above the top of the kerb. The kerb shall be a minimum of 125 mm wide

by 300 mm deep in clay soils. The kerb shall be a minimum of 125 mm wide by 600 mm deep in

sandy soils. The top of the kerb shall be no less than 50 mm above ground level.

If a kerb cannot be used, then a concrete path shall be constructed. This path shall extend a

minimum of 600 mm from the fence line. The path shall have a minimum depth of 75 mm and

finish flush with the existing ground levels. The bottom of the fence shall not be more than

50 mm above the concrete.

The construction of the kerb and path is as shown on EL 0450711 Substations Fencing Sheet 4

Details. The kerb and path shall be constructed in accordance with AS 3600 Concrete

Structures.

The design of kerbing and paths shall consider surface drainage issues, to minimise, for

example:

• water ponding, and

• fouling of the substation yard from silt runoff

6.10. Ground level and fence height If possible, the ground below the fence shall be level. The ground below the fence shall not be

exposed to erosion or subsidence. The fence shall be designed such that if the ground

transitions from one level to the next, climbing aids are not created.

In areas where ground level is sloped a retaining wall shall be constructed to provide support.

The retaining wall shall be designed and constructed to support the integrity of the fence. The

line of the fence shall progress down the slope in a series of level steps. The kerb or path shall

be included into the design of the retaining walls.

Where necessary, adjustments to the existing ground levels shall include surface drainage

measures to prevent water ponding.

6.11. Climbing aids

6.11.1. Intruder resistant fences

The vertical clearance of the fence above a climbing aid (which cannot be removed or

relocated), shall be a minimum of 2.4 m including the topping installed. Fence posts shall be

extended to allow for this on both sides of the climbing aid. Typical clearances shall be in

accordance with drawings EL 0450712 Substations Fencing Clearances to Climbing Aids and

EL 0450710 Substation Fencing Typical Construction.




All potential climbing aids shall have measures to prevent unauthorised entry. The fence design

shall ensure that any climbing aid is 3 m or more away from the fence. If this is impractical, then

the following shall be considered:

• Traffic bollards or barriers – increase the height of the fence above the barrier to ensure

minimum height. Refer to EL 0450710 Substations Fencing Sheet 3 Typical Construction.

• Windowsills – place security grille or mesh flush over window so no finger or footholds are

available.

• Gate locks – the locks shall not create an external foot or hand hold. Refer to EL0450709

Substations Fencing Sheet 2 Typical Construction.

• Stairs – remove or relocate stairs, or provide increase in fence height, or do both.

Otherwise, provide a security grill or mesh around the stairs.

• Adjacent fence – where an abutting fence cannot be removed or relocated, then increase

the height of the intruder resistant fence to 2.4 m above the highest foothold. Refer to

EL 0450712 Substations Fencing Sheet 5 Clearances to Climbing Aids.

• Adjacent pole – if the pole cannot be removed or relocated then the fence shall be

redirected around the pole so that there is a clearance of at least 2 m.

• Overhanging vegetation – remove or prune back to 3 m away from the fence. If this is not

possible, trim trunk smooth to a height of 6 m to remove any climbing aids. Refer to

EL 0450712.

6.11.2. Other substation fences Where practicable, ensure structures adjacent to substation boundary and internal enclosure

fences are located and configured so as not to act as a climbing aid to the fence. The site

specific risk assessment may necessitate the use of the anti-climb methods nominated for

intruder resistant fences (refer to Section 6.11.1).

6.12. Gates Both vehicular and pedestrian gates shall be made of the same material as the fence. Each

gate shall have a concrete path or driveway provided underneath it.

The gateposts shall be of suitable strength to support the gate with reliable operation, for the

duration of the fence life. Double gates shall have a top, middle, and bottom rail and shall be

braced as shown in EL 0450709 Substations Fencing - Typical Construction - Arrangement -

Sheet 2.

The gates and posts shall be all-welded, galvanised and powder coated and be constructed in

accordance with EL 0450709. The topping for vehicle gates shall be straight up, not canted. The

topping for the pedestrian gate can be a continuance of the adjacent topping. © State of NSW through Transport for NSW 2017 Page 15 of 23



Sliding gates are not preferred; however, they may be used as vehicular gates subject to ASA

approval.

6.12.1. Emergency egress gates

The design shall allow for the safe egress of personnel during a fire, severe equipment failure,

and other emergencies. Refer to T HR EL 99002 ST for details.

If there is insufficient space inside the substation fence for a safe area to evacuate to, then

there shall be an emergency egress gate in the substation fence to allow egress to the outside.

As part of the design process, the AEO shall prepare an emergency evacuation plan that clearly

identifies the nominated emergency gates and emergency egress pathways. The emergency

evacuation plan shall ensure that egress is to a safe location and not onto live rail lines or

roadways.

For a typical emergency egress gate, refer to EL 0455333 Substations Fencing - Typical

Construction - Emergency Egress Gate.

EL 0455333 specifies the following requirements for emergency egress gates:

• the gate shall have a transparent impenetrable barrier (typically a high strength, high

impact resistant acrylic or polycarbonate) surrounding the lock

• the gate shall have a welded plate across the gate to jamb gap on the lock side for the full

height of the gate

The lock shall be a single downward thrust action for egress, and the gate shall open in the

direction of the emergency egress. The locking tongue shall penetrate the striker plate to a

distance of a minimum of half the length of the locking tongue.

To minimise the risk of intruders being able to reach the gate release from the adjacent side

fence panel, emergency egress gates shall not be located in corners of fences.

The location of an emergency egress gate shall not interfere with the bracing required as

specified in Section 6.6.

The use of emergency egress gates shall be limited to those nominated in the emergency

evacuation plan as these gates are not as secure as those fitted with sliding bolt with padlock.

6.12.2. Hinges

The hinges shall be made of galvanised steel. The hinges shall be strong enough to ensure

reliable operation of the gate over the fence lifetime. The hinges shall require minimum

maintenance. The hinges shall be designed to ensure that the gate cannot be removed in the

closed position.




6.12.3. Locks

The locking arrangement of gates shall be as shown in EL 0450709 Substations Fencing -

Typical Construction - Arrangement - Sheet 2.

For vehicular double gates, each gate shall be fixed by a galvanised padlock-able drop barrel

bolt (minimum 16 mm diameter) into the ground. Galvanised steel pipes shall be set into the

concrete for this purpose; refer to details shown on EL0450709. The two gates shall then be

locked together with a galvanised padlock-able sliding bar.

For pedestrian gates, the lock shall be a high security, exterior grade, sliding bolt with a

padlock. The bolt shall travel a minimum of 20 mm into the post on lock. The lock plate on the

outside of the gate shall be flush mounted and tamper proof.

The position of all locks shall be as shown on the drawings and mounted between 900 mm and

1200 mm above the ground level.

6.13. Clearance zone A 3 m horizontal clearance zone should be maintained around the substation fence. The

clearance zone should be kept free of intermediate structures, hazards, climbing aids, large

vegetation, and any form of material build-up. If the 3 m clearance is not practical, then the

maximum possible clearance is required, and any possible climbing aids are to be dealt with in

accordance with this standard.

6.14. Vegetation Any vegetation planted around the fence inside the clearance zone shall not have a potential

height greater than 300 mm. This ensures there are no areas close to the fence that allow

coverage for intruders.

7. Electrical clearance Electrical clearances to substation fences shall comply with Section 5.2 of AS 2067:2016.

As 1500 V dc is not included in the scope of AS 2067, for 1500 V dc use the clearances

specified for 11 kV ac.

If the specified clearances for mesh fencing cannot be achieved, one or all of the following shall

be carried out:

• relocate the fence to achieve the clearances

• move or insulate the live exposed equipment

• install a non-penetrable panel in the fence, in which case the reduced clearances for solid

wall construction may be used




7.1. Non-penetrable panel The non-penetrable panel shall be as shown in EL 0450713. This panel will typically be of two

layers of compressed fibrous cement panel (2.4 m x 1.2 m x 18 mm) one on the front, and one

on the back of the steel posts. All fixings shall be countersunk type and the holes back filled with

a two part epoxy resin.

The topping over the non-penetrable panel(s) shall be continuous with the topping over the

adjacent panels.

Sufficient panels shall be installed to achieve the required electrical clearances.

Alternate materials or configurations, or both, for the non-penetrable panel may be proposed by

the AEO, and are subject to approval by ASA. The AEO shall assure the proposed option

including, but not limited to, whole-of-life costs and considerations, maintenance requirements,

and any alterations to technical maintenance plans (TMPs).

8. Substation fence earthing, bonding and isolation The design of the fence shall be coordinated with the design of the earthing system and shall

comply with EP 12 10 00 10 SP System Substation Earthing to avoid the creation of situations

in which the step or touch potentials are unacceptable, and to ensure that high earth potential

rise is not transferred beyond the zone where the potential gradient is properly controlled.

8.1. Earthing and bonding Earthing and bonding requirements for substation fencing, gate bonding, grading rings, and so

forth shall be in accordance with the TfNSW earthing standards.

Typically, substation fences are bonded to the substation earth grid. Any continuous metallic

fencing adjacent to the substation boundaries is isolated by insulated fence panels; however

fences can also be isolated or insulated where deemed appropriate.

The designer shall consider stray current, step, touch and transfer potential issues in

determining the earthing and bonding requirements for fencing and gates. Gates shall be

assessed for all operational positions.

Earth grading rings in close proximity to concrete paths shall be avoided.

8.2. Isolation and transfer potential mitigation All substation fencing and any supporting structures shall be electrically isolated from any other

conductive fencing beyond the substation boundaries. The location and number of substation

fence isolation points shall be subject to earthing design.




The approved method for implementing fence isolation shall be through provision of an

insulated fence panel. Insulation panels are detailed in Section 11 of SPC 511, version 1.1.

Continuous reinforced concrete structures supporting uninsulated fences shall have

reinforcement isolated at points in line with any required fence isolation so as to break the

continuity of the reinforcement and maintain the integrity of the isolation point. Only a single

isolation point is required in line with the insulated fence section to maintain the integrity of the

insulated fence panel.

Approved insulating pads, ferrules and washers may be used to provide isolation between fence

panels and supporting reinforced concrete structures so long as the number of attachments

does not compromise the minimum insulation requirements.

The specification of insulation shall include measures to insulate security structures such as

fence toppings. The security structures shall not compromise the intended isolation points.

Where a continuous metallic structure is in contact with the fence, then an insulating section

shall be included in the design (of either the fence or the structure) to stop transfer potentials

through, into and out of the metallic structure.

Where an overhead wiring structure is located within 2 m of a substation fence, an insulating

panel shall be installed to achieve 2 m separation from any uninsulated fence panels.

8.3. Testing and measurement Visual inspection and step, touch and transfer potential measurements shall be used to validate

the design and installation of fence isolation and to ensure compliance. Testing of fence

isolation is mandatory if the maximum earth potential rise (EPR) at the substation is within 10%

of the allowable limits.

Continuity testing shall be conducted between the earth grid and the fence upon installation to

ensure adequate bonding has been installed. Pass and fail criteria shall be developed and

specified by the designer. Where bonding is required, more than one connection to the earth

grid shall be provided to any continuous fence section to provide redundancy.

9. Signage Signage shall be installed in accordance with T HR EL 00006 ST Electrical Power System

Signage.

In addition, if the fence construction includes barbed tape (razor wire) or palisade spikes, then

danger signs shall be installed warning of their presence.

Signs shall be placed to ensure that they are clearly visible and easily read.




10. Construction factors During construction of a new or replacement fence, the risk of unauthorised access to the site

and to exposed electrical equipment shall be managed as part of the overall risk assessment.

This includes, but is not limited to, the following:

• the need for temporary protection measures

• monitoring the integrity of all access prevention methods

• development of safe work method statements (SWMS) or safe work instructions (SWIs) as

necessary

Identification of, and work around, buried services shall be conducted in accordance with

approved procedures. In addition, the design and construction of the fence shall consider and

manage the likelihood that the substation grading ring may be located outside the existing

substation fence line.

Refer to Section 10 of T HR CI 12160 ST, version 1.0 for more information.

11. Maintenance Substation fencing shall be inspected and maintained in accordance with the technical

maintenance plan, and Section 11 of T HR CI 12160 ST, version 1.0.

Any encroachment by vegetation shall be managed, to ensure clearances are not breached and

sighting of intruders is not impeded.




Appendix A Additional references and drawings The list of documents and drawings in Section A.1 and Section A.2 may provide additional

information and context.

A.1. Documents AS 1725:2003 Chain-Link Fabric Security Fences and Gates

AS 4100 Steel Structures

AS/NZ 2312:2002 Guide to the Protection of Structural Steel against Atmospheric Corrosion by

the Use of Protective Coatings

AS/NZS 4534:2006 Zinc and zinc/aluminium-alloy coatings on steel wire

BS 1722-10:1999 Fences – Part 10: Specification for Anti-Intruder Fences in Chain Link and

Welded Mesh

BS 1722-14:1999 Fences – Part 14: Specification for Open Mesh Steel Panel Fences

EP 12 10 00 11 SP Distribution Substation Earthing

EP 12 10 00 21 SP Low Voltage Installation Earthing

T HR EL 12002 GU Electrolysis from Stray DC Current

A.2. Drawings The following drawings have not been AEO assured or accepted for TfNSW use; however, they

may provide additional reference material:

CV0393068 Substations Fencing Upgrades Sheet 1 Cover Sheet and Notes

CV0393069 Substations Fencing Upgrades Sheet 2 General Details

CV0393070 Substations Fencing Upgrades Sheet 3 Increase Fence Height and Barbed Tape

CV0393071 Substations Fencing Upgrades Sheet 4 Details of Gates

CV0393073 Substations Fencing Upgrades Sheet 6 Kerbing

CV0393074 Substations Fencing Upgrades Sheet 7 Locking and Bolting Details




Appendix B Substation fencing examples The information in Section B.1 to Section B.3 provides informative guidance material to assist in

interpreting this standard.

B.1. Traction SS, section hut, or system SS – Indoor HV switchgear The site is defined by a boundary fence (see Section 5.1 and Section 6.3). This is typically

2.7 m high welded mesh, with croc top topping dependent on site risk assessment. This

includes sites where one wall of the substation building is facing the rail corridor - an extra line

of defence is recommended to deter vandalism of the SS building.

The HV switchgear and associated substation (SS) auxiliary and control equipment will be

contained within an intruder resistant building, typically not less than 3 m from the boundary

fence.

The transformers (rectifier or system or DC reactor) whether they are cable entry or bushing

entry, will be within an intruder resistant enclosure. The enclosure may be of masonry

construction, or welded mesh (Section 6.4) or a combination of both; for example, the

substation building itself may constitute one or more intruder resistant walls for the transformer

enclosure.

The 1500 V link area will be contained within an intruder resistant enclosure, typically a welded

mesh fence (Section 6.4), or contained within the substation building.

B.2. Traction SS or system SS – Outdoor HV switchgear and exposed busbars This configuration will normally only apply to pre-existing substations. Preference is for new

substations to be designed with enclosed switchgear.

The site should be defined by a boundary fence (Section 5.1 and Section 6.2), which should be

not less than 3 m from the intruder resistant fence (Section 6.4). Typically, due to site

constraints, the exposed HV equipment occupies such a significant portion of the site as to

preclude space for a separate boundary fence. However, the design for the intruder resistant

fence should attempt to accommodate the requirements of this standard. For example, the

design should attempt to constrict the alignment of the intruder resistant fence to enable the

provision for a boundary fence whilst not infringing the clearance defined in AS 2067.




B.3. 1500 V link or switch enclosure (free standing) The same principles detailed in Section B.2 apply for a SS yard with exposed HV conductors,

including but not limited to, the provision of an intruder resistant enclosure, and AS 2067

requirements for string line distances to exposed 1500 V conductors.

Such equipment is normally located within the rail corridor. Due to site constraints, there may

not be sufficient space for a separate boundary fence, therefore the site specific risk

assessment should consider the adequacy of any existing boundary fences, and define safe

access and egress routes for the link or switch enclosure.


Technical Note – TN 006: 2019 - Transport for NSW...If you use this document or rely upon it...

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Transcript of Technical Note – TN 006: 2019 - Transport for NSW...If you use this document or rely upon it...