pssi 16 opsaf-10-016 high voltage overhead lines work on

PSSI 16 High Voltage Overhead Lines – Work on Towers,

Poles, High Structures and Earthwires

OPSAF-10-016 Issue No. 2

© SP Power Systems Limited of 29 PSSI 16

FOREWORD

This Safety Instruction details the safety requirements for working on towers, poles and high structures carrying Live conductors where the work does not require the infringement of Safety Distance to any phase conductors, insulators or associated fittings. It also specifies the safety precautions for working on earthwires. The Attachments to this Safety Instruction give in detail the requirements for providing and maintaining earthwire continuity and bonding, particularly when changing earthwire fittings, and the Safety from the System requirements for the continuous tension stringing of earthwires. The requirements for the provision and maintenance of Equipotential Zones are specified in Appendix B to PSSI 4. Mention is made of the management considerations that shall be addressed with particular reference to the Electricity at Work Regulations 1989 for working on earthwires in proximity to Live conductors.

1. SCOPE

This Safety Instruction applies the principles established by the ScottishPower Safety Rules (Electrical and Mechanical) and the Company Safety Instructions to enable personnel to maintain Safety from the System when working on towers, poles, high structures and earthwires. Attachment A to this Safety Instruction gives in detail the requirements for applying and removing Permanent Earth Bonds or Temporary Earth Bonds to meet certain work requirements. Attachment B covers the Safety from the System requirements for continuous tension stringing of earthwires, under single circuit outage conditions, on double circuit 132/275/400kV overhead lines. Work on, or within the Safety Distance of, phase conductors, insulators and associated fittings is outside the scope of this Safety Instruction and is covered in PSSI 4.

2. ISSUE RECORD

This is a Reference document. The current version is held on the EN Document Library. It is your responsibility to ensure you work to the current version.

Issue Date Issue No. Author Amendment Details

October 1998 1 Initial Issue September 2015 2 Phil Currie Foreword re-worded; reference to line patrols removed;

reference to optical cables removed. Definitions – some removed as now covered in Part D, Appointed Wiring Observer added. 10.1 removed reference to conductive footwear. 10.2 provision for single Person working at height in limited circumstances. 11.2 fixing of red pennants or bands and tower painting requires Immediate Supervision. 12.1 added requirement for a Permit for Work. 12.2 Re-worded and new requirement added to remedy defective Earth Bonds before continuing other work. 14 change to Control Person’s responsibilities re lightning. Attachment A Scheme 3 reviewed and updated. Attachment A Scheme 4 withdrawn. Attachment B – reviewed and updated. Attachments C, D and E removed.





3. ISSUE AUTHORITY

Author Owner Issue Authority

Name: Phil Currie Title: Operational Compliance Manager

Name: Phil Currie Title: Operational Compliance Manager

Name: Colin Taylor Title: Director, Engineering Services

4. REVIEW

This is a Reference document which has a 5 year retention period after which a reminder will be issued to review and extend retention or archive.

5. DISTRIBUTION

This Energy Networks’ Safety Instruction is maintained by EN Document Control and is part of the ScottishPower Safety Rules which is published to the SP Energy Networks Internet site.





6. CONTENTS

FOREWORD .................................................................................................................................................... 1

1. SCOPE ..................................................................................................................................................... 1

2. ISSUE RECORD ...................................................................................................................................... 1

3. ISSUE AUTHORITY ................................................................................................................................. 2

4. REVIEW .................................................................................................................................................... 2

5. DISTRIBUTION ........................................................................................................................................ 2

6. CONTENTS .............................................................................................................................................. 3

7. DEFINITIONS ........................................................................................................................................... 4

8. APPARATUS IDENTIFICATION .............................................................................................................. 4

9. DANGERS ................................................................................................................................................ 4

10. GENERAL REQUIREMENTS FOR WORK ON TOWERS, POLES AND HIGH STRUCTURES ............ 5

11. WORK ON TOWERS, POLES AND HIGH STRUCTURES CARRYING LIVE CONDUCTORS WHERE THE WORK DOES NOT REQUIRE THE INFRINGEMENT OF SAFETY DISTANCE TO ANY CONDUCTORS, INSULATORS OR ASSOCIATED FITTINGS (EXCLUDING WORK ON EARTHWIRES) .. 6

12. WORK ON EARTHWIRES ....................................................................................................................... 6

13. MANAGEMENT CONSIDERATIONS FOR WORK ON EARTHWIRES .................................................. 7

14. ADVERSE WEATHER CONDITIONS ...................................................................................................... 7

15. EQUIPOTENTIAL ZONES ....................................................................................................................... 7

ATTACHMENT A – EARTH BONDING SCHEMES ........................................................................................ 8

1. General Principles ......................................................................................................................... 8

2. General Requirements for Earth Bonding ................................................................................... 8

3. Earth Bonding Schemes ............................................................................................................... 8

ATTACHMENT A SCHEME 1 – REMAKE/REPLACE EARTHWIRE PERMANENT EARTH BONDS AND REPLACE EARTHWIRE SUSPENSION CLAMP ASSEMBLIES ................................................................. 10

ATTACHMENT A SCHEME 2 – REMAKE/REPLACE EARTHWIRE PERMANENT EARTH BONDS AND/OR JUMPER CONNECTIONS ............................................................................................................. 12

ATTACHMENT A SCHEME 3 – EARTHWIRE REPLACEMENT USING CONTINUOUS TENSION STRINGING METHODS UNDER SINGLE CIRCUIT OUTAGE CONDITIONS ON DOUBLE CIRCUIT 132/275/400KV OVERHEAD LINES ............................................................................................................. 14

1. Prepare Section of Overhead Line for Pulling New Earthwire ................................................. 14

2. Sagging and Landing the New Earthwire .................................................................................. 19

ATTACHMENT A SCHEME 4 – INSTALLATION OF OPTICAL EARTHWIRE USING CRADLE BLOCK TECHNIQUE ON DOUBLE CIRCUIT 275/400KV OVERHEAD LINES WITH BOTH CIRCUITS LIVE ........ 22

ATTACHMENT B – SAFETY FROM THE SYSTEM REQUIREMENTS FOR CONTINUOUS TENSION STRINGING OF EARTHWIRES UNDER SINGLE CIRCUIT OUTAGE CONDITIONS ON DOUBLE CIRCUIT 132/275/400KV OVERHEAD LINES ............................................................................................................. 23

1. Scope ............................................................................................................................................ 23

2. Basic Safety Requirements ......................................................................................................... 23

3. Basic Requirements to Safeguard Personnel ........................................................................... 24

APPENDIX A: CHECKLIST OF KEY EARTHWIRE PULLING ACTIVITIES FORM .................................... 29





7. DEFINITIONS

For the purpose of this Safety Instruction and Attachments the following definitions apply: 7.1 Appointed Wiring Observer – a Person with sufficient technical knowledge and experience of

the work to be undertaken, the techniques to be employed and the Safety from the System implications. He shall be specifically nominated by the Senior Authorised Person on Appendix A to Attachment B: Checklist of Key Earthwire Pulling Activities Form. He shall be present on site during the work with his attention dedicated to this task. His role is as a back-up observer of the work being carried out, to ensure that all appropriate measures required by this Safety Instruction are being complied with by the Working Party. Responsibility for maintaining Safety from the System remains with the Safety Document recipient who retains full responsibility for the safety of the Working Party.

7.2 Earth Bonds – Approved bonds for the purposes of providing:

(i) Earth continuity for the earthwire;

(ii) An earth connection between the earthwire and the tower;

(iii) A connection between the earthwire and the general mass of earth.

7.3 Temporary Earth Bonds Permanent Earth Bonds All being forms of Earth Bonds. Running Earth Bonds

7.4 Field Equipment Earths – Approved connections for bonding items of field equipment to earth. Field Equipment Earths are distinctively marked to identify them from Drain Earths and are not included on an Earthing Schedule.

7.5 Equipotential Zone Bonds – Approved connections for the purpose of bonding tensioners,

pullers, reel winders, drums and associated equipment together, and to footplates, to ensure that the operators and the equipment are at the same potential.

7.6 Upper Portion – of towers, poles and high structures are those parts which are:

(a) Within the Safety Distance from HV conductors; and/or

(b) Within 300mm of unearthed steelwork supporting HV conductors or bonded to unearthed steelwork supporting HV conductors; and/or

(c) Above a horizontal line through the lowest HV conductor. Terms printed in bold type are as defined in the ScottishPower Safety Rules (Electrical and Mechanical).

8. APPARATUS IDENTIFICATION

Apparatus on which work or testing is to be carried out shall be readily identifiable or have fixed to it a means of identification which shall remain effective throughout the course of the work or testing.

9. DANGERS

The main Dangers to personnel working on overhead lines and towers are electric shock, burns or falls, arising from:

(i) The possibility of personnel mistaking overhead line HV Apparatus on which it is unsafe to work for that on which it is safe to work;





(ii) The application of Earthing Devices to Live HV Apparatus;

(iii) Inadvertently infringing Safety Distance;

(iv) Inadequate precautions to suppress or safely discharge any induced or other impressed voltages in the conductors and associated fittings;

(v) Inadequate precautions to provide and maintain an equipotential environment for the operators of tensioners and pullers and personnel working on associated equipment;

(vi) Badly connected or insecure Earthing Devices or Earth Bonds;

(vii) Insecure hand and footholds;

(viii) Failure to make proper use of fall arrest equipment.

10. GENERAL REQUIREMENTS FOR WORK ON TOWERS, POLES AND HIGH STRUCTURES

10.1 All Persons working on towers, poles and high structures shall wear and make proper use of Approved PPE which is provided for their safety and protection. This equipment shall be examined on each occasion before use.

10.2 Any Person working on a tower, pole or high structure shall be in visual range of at least one

other Person except where that work is of a minor nature and of short duration, covered by an Approved procedure and can be completed from a restricted height of up to 2 metres (distance from ground to Person’s feet).

10.3 Before any wood pole is climbed it shall be sounded, and the condition of the foundations and

the effectiveness of any stays examined. No pole badly impaired by decay or damage or considered unstable shall be climbed until it has been supported by Approved means.

10.4 Where a Person is working on a tower, pole or high structure no work shall be carried out

which may affect its stability. 10.5 The release of tension in, and the lowering of, earthwire conductors and stays shall be carried

out in a controlled manner in accordance with Approved procedures. 10.6 In assessing Safety Distance, consideration shall be given to insulator and conductor

movement due to wind conditions. 10.7 Step bolts may be used provided that Safety Distance to any part of the climber's body, or

anything being carried, is not infringed. Where the Safety Distance cannot be maintained whilst using step bolts, climbing shall be within the body of the tower or on the face of the tower at right angles to the conductors.

10.8 At tee-off, terminal and large angle towers, reduced clearances to Live conductors can occur.

When work is being carried out on such towers, the Senior Authorised Person preparing the Safety Document shall decide what special arrangements are to be undertaken and whether the work shall be carried out under the Personal Supervision of a Senior Authorised Person.

10.9 Anti-climbing guard gates shall be secured and effective when work is completed or when

Persons have descended from the tower, pole or high structure and the site is left unattended.





11. WORK ON TOWERS, POLES AND HIGH STRUCTURES CARRYING LIVE CONDUCTORS WHERE THE WORK DOES NOT REQUIRE THE INFRINGEMENT OF SAFETY DISTANCE TO ANY CONDUCTORS, INSULATORS OR ASSOCIATED FITTINGS (EXCLUDING WORK ON EARTHWIRES)

Painting, inspection and other work on towers, poles or high structures not involving the infringement of Safety Distance to HV conductors, insulators or associated fittings shall only be carried out under the conditions given below. 11.1 Work outside the Upper Portions of towers, poles or high structures, may be carried out by an

Authorised Person on any tower, pole or high structure carrying Live HV conductors provided that:

(i) there is no infringement of Safety Distance; and

(ii) a distance of 300mm is maintained from unearthed metalwork which is outside the Safety Distance, but bonded to metalwork that is within the Upper Portion.

11.2 Work on the Upper Portions of towers, poles or high structures in close proximity to, but

outside Safety Distance from Live HV conductors may be carried out by an Authorised Person provided that:

(i) If necessary to avoid infringement of Safety Distance, the Senior Authorised

Person preparing the Safety Document shall specify the positions at which red pennants or a red marker band shall be fixed to define the limits of access. Before any Person is allowed to start work the Authorised Person in charge of the work shall ensure that the red pennants or red marker band are so fixed. The Authorised Person(s) fixing the red pennants or red marker band shall be under the Immediate Supervision of another Authorised Person who shall communicate with him to warn of any possible infringement of Safety Distance. This Authorised Person may be a member of the Working Party positioned on the ground or on the tower, pole or high structure;

(ii) Where painting of towers or high structures is taking place, the Person(s) involved shall be under the Immediate Supervision of an Authorised Person who shall be able to communicate with those Persons to warn of any possible infringement of Safety Distance. This Authorised Person may be a member of the Working Party positioned on the ground or on the tower, pole or high structure. The work shall be carried out under a Limited Work Certificate. Any restrictions shall be stated on the Limited Work Certificate.

12. WORK ON EARTHWIRES

12.1 Work on earthwires involving the erection or lowering of the wires, or any other work likely to cause a significant increase in the normal sag of the earthwire in any span shall, where reasonably practicable, be carried out with all associated circuits Isolated and Earthed and a Permit for Work issued. Where, due to special circumstances, it is not reasonably practicable to isolate and earth circuits, the work shall be carried out in accordance with an Approved procedure.

12.2 For any work other than that referred to in 12.1 and where Safety Distance can be

maintained, a Limited Work Certificate shall be issued. Any restrictions shall be stated on the Limited Work Certificate. The connection to earth of the earthwire by way of earthwire bonding and the electrical continuity of the earthwire at the point of work shall be maintained. Temporary Earth Bonds shall always be fitted before Permanent Earth Bonds are disconnected or removed. Defective or missing Earth Bonds shall be replaced before any work continues on the Upper Portion of a tower.





13. MANAGEMENT CONSIDERATIONS FOR WORK ON EARTHWIRES

13.1 In accordance with the requirements of 12.1 and 12.2 of this Safety Instruction consideration shall be given to the nature of the work to be carried out on the earthwire and the consequential need for circuit outages.

13.2 Management considerations for work on earthwires in proximity to Live conductors are

detailed in OPSAF-11-020 (MSP 2.9).

14. ADVERSE WEATHER CONDITIONS

In the event of, or the near approach of, a lightning storm, all work on overhead lines shall cease immediately and the Control Person shall be notified. If the Control Person becomes aware of a lightning storm (or risk of lightning) he shall, where reasonably practicable, communicate this to all relevant parties. Attachment B has a specific section relating to weather conditions.

15. EQUIPOTENTIAL ZONES

The requirements for the provision and maintenance of Equipotential Zones to protect the operator of a tensioner or a puller/winch and the personnel working on reel winders, drums and associated equipment against the effects of any rise in potential of the machines and equipment in respect to the ground they are standing on are specified in Attachment B to PSSI 4.





ATTACHMENT A – EARTH BONDING SCHEMES

1. General Principles

1.1 The Schemes detailed in this Attachment indicate the requirements for the application of Earth Bonds in preparation for various work procedures. The methods detailed are for normal requirements and may be supplemented if necessary in particular work circumstances. In applying the Schemes, the requirements of PSSI 16 and the Attachments shall be met.

1.2 Where there is no Scheme to cover a particular work situation, a combination of Schemes or a modification of a Scheme to suit the different circumstances may be used. The Senior Authorised Person shall ensure that the recipient of the Safety Document is aware of the requirements of the modified Scheme.

2. General Requirements for Earth Bonding

2.1 Earth Bonds shall have a cross-section of not less than 25 sq mm copper equivalent, and shall be effectively applied between the bonding points indicated in these Schemes. Temporary Earth Bonds should be no longer than necessary and normally no longer than 1.5 metres.

2.2 Earth Bonds shall be applied in accordance with the following:

(i) Before uncoiling Temporary Earth Bonds at the tower top position, each earth end clamp shall first be attached to the tower steelwork and tightened so that the tip of the clamping screw penetrates any paint film and provides a good electrical and mechanical connection. When the earth end clamp is secured, the Temporary Earth Bond can then be uncoiled and the conductor end clamp firmly applied to the conductor using an Approved earthing pole;

(ii) If an Earth Bond is found to be defective in service a further Earth Bond shall be fitted in parallel with the defective earth. When this has been done the defective Earth Bond may be removed, taking care not to disturb the effective Earth Bond;

(iii) The removal of Temporary Earth Bonds shall be carried out in the reverse sequence to (i) above.

3. Earth Bonding Schemes

3.1 Temporary earth bonding is unnecessary when replacing earthwire dampers where the integrity of the Permanent Earth Bonds has been confirmed before work starts.

3.2 The safety precautions detailed in PSSI 16 and the Attachments shall be specified on any Limited Work Certificate issued to carry out the specific task.

3.3 Index of Earth Bonding Schemes

Scheme 1 Remake/replace earthwire Permanent Earth Bonds and replace earthwire clamp assemblies. Scheme A – On terminal towers. Scheme B – On suspension towers.





Scheme 2 Remake/replace earthwire Permanent Earth Bonds and/or jumper connections. Scheme A – On pointed peak tension towers with bolted jumper connections. Scheme B – On square peak tension towers with wedge tap connected jumpers.

Scheme 3 Earthwire replacement using continuous tension stringing methods under single circuit outage conditions on double circuit 132/275/400kV overhead lines. (Attachment B refers).

Note: The drawings within the Schemes are representative of typical tower peaks. The

actual configuration of tower peaks, earthwires, shoes, fittings and bonds may vary with the type of tower, but the principles will remain the same.





ATTACHMENT A SCHEME 1 – REMAKE/REPLACE EARTHWIRE PERMANENT EARTH BONDS AND REPLACE EARTHWIRE SUSPENSION CLAMP ASSEMBLIES

A ON TERMINAL TOWERS A 1.1 Apply a single Temporary Earth Bond before remaking or replacing the earthwire Permanent

Earth Bond (Fig. 1). A 1.2 Remove the Temporary Earth Bond on completion of the task.

SCHEME 1 FIG. 1

PERMANENT EARTH BOND

TEMPORARY EARTH BOND





B ON SUSPENSION TOWERS B 1.1 Apply a single Temporary Earth Bond before remaking or replacing the earthwire suspension

clamp assembly (Fig. 2). B 1.2 Remove the Temporary Earth Bond on completion of the task.

SCHEME 1 FIG. 2

PERMANENT

EARTH BOND

TEMPORARY

EARTH BOND





ATTACHMENT A SCHEME 2 – REMAKE/REPLACE EARTHWIRE PERMANENT EARTH BONDS AND/OR JUMPER CONNECTIONS

A ON POINTED PEAK TENSION TOWERS WITH BOLTED JUMPER CONNECTIONS A 1.1 Apply two Temporary Earth Bonds before remaking or replacing the earthwire Permanent

Earth Bond and/or bolted jumper (Fig. 1). A 1.2 Remove the Temporary Earth Bonds on completion of the task.

SCHEME 2 FIG. 1

THROUGH JUMPER

PERMANENT EARTH BOND

ALTERNATIVE WEDGE TYPE CONNECTION







B ON SQUARE PEAK TENSION TOWERS WITH WEDGE TAP CONNECTED JUMPERS B 1.1 Apply two Temporary Earth Bonds before remaking or replacing the earthwire Permanent

Earth Bond and/or wedge tap connected jumper (Fig. 2). B 1.2 Remove the Temporary Earth Bonds on completion of the task.





ATTACHMENT A SCHEME 3 – EARTHWIRE REPLACEMENT USING CONTINUOUS TENSION STRINGING METHODS UNDER SINGLE CIRCUIT OUTAGE CONDITIONS ON DOUBLE CIRCUIT 132/275/400KV OVERHEAD LINES

1. Prepare Section of Overhead Line for Pulling New Earthwire

1.1 No work that could possibly affect the mechanical integrity of the earthwire shall take place unless the phase wires of the Isolated and Earthed circuit are continuous between the towers either side of the section to be pulled and Drain Earths are fitted to all phase conductors on the Isolated and Earthed circuit at all towers in the section to be worked on and at the nearest towers on each side of the section. The Drain Earths shall remain in position for the duration of the work in the section.

1.2 At Nearest Towers Each Side of Section

Permanent Earth Bonds shall be checked and confirmed to be in good and serviceable condition. This shall take place before any break is made in the continuity of the earthwire at puller/tensioner towers or intermediate tension towers.

1.3 At Intermediate Tension Towers

(i) Apply two Temporary Earth Bonds before removing dampers and earthwire Permanent Earth Bonds and through jumper connection (Fig. 1);

(ii) Catch-off and cut out each termination in turn.

SCHEME 3 FIG. 1

PERMANENT

EARTH BOND

PERMANENT

EARTH BOND

TEMPORARY

EARTH BOND

THROUGH JUMPER

TEMPORARY

EARTH BOND





(iii) Fit running block, join earthwires together using an Approved method and pass through running block;

(iv) Transfer one Temporary Earth Bond to running block spigot. If in a section with no sensitive crossings, and only with the agreement of the Senior Authorised Person, remove catch-off rigs and the remaining Temporary Earth Bond ready to pull (Fig. 2). The Senior Authorised Person may stipulate that the catch-off rigs are only removed on the day that the earthwire will be pulled.

SCHEME 3 FIG. 2

TEMPORARY

EARTH BOND





1.4 At Each Suspension Tower in the Section

(i) Apply two Temporary Earth Bonds to the earthwire (Fig. 3);

(ii) Fit running block, support the earthwire whilst removing the dampers, Permanent Earth Bond and suspension clamp assembly;





(iii) Place the earthwire in the running block and transfer one of the Temporary Earth Bonds to the running block spigot (Fig. 4);

(iv) Remove the remaining Temporary Earth Bond from the earthwire.

1.5 At the Puller End Tension Tower

(i) Set up Equipotential Zone for the puller, drum winder and associated equipment in accordance with PSSI 4 Attachment B (see Fig. 7);

(ii) Apply two Temporary Earth Bonds (only one required if terminal tower) before removing appropriate damper, earthwire Permanent Earth Bonds and through jumper;

(iii) Catch-off appropriate side and cut out termination;

(iv) Fit running block and apply additional Temporary Earth Bond to the running block spigot;

(v) Pull reeving rope/pulling bond though the puller, raise up tower and pass through running block. Join to old earthwire using Approved method. Where a square rig arrangement is being used, a Temporary Earth Bond shall be applied to the running block at the bottom of the tower before the reeving rope/pulling bond is passed through it and raised up the tower;

(vi) Remove Temporary Earth Bond from old earthwire to be replaced. Leave the Temporary Earth Bond in place on the old earthwire not being replaced (Figs. 5 and 7);

(vii) The catch-off rigs shall only be removed from the earthwire when the Senior Authorised Person gives the instruction to do so. This instruction shall only be given once the Senior Authorised Person has carried out the appropriate checks and issued the Permit for Work to run the new earthwire.





1.6 At the Tensioner End Tension Tower

(i) Set up Equipotential Zone for the tensioner, drum stand and associated equipment in accordance with PSSI 4 Attachment B (see Fig. 6);

(ii) Apply two Temporary Earth Bonds (only one required if terminal tower) before removing appropriate damper, earthwire Permanent Earth Bonds and through jumper;

(iii) Catch-off appropriate side and cut out termination;

(iv) Fit running block and apply additional Temporary Earth Bond to the running block spigot;

(v) Pull new earthwire through tensioner, raise up tower and pass it through the running block. Join to old earthwire using an Approved method. Where a square rig arrangement is being used, a Temporary Earth Bond shall be applied to the running block at the bottom of the tower before the new conductor is passed through it and raised up the tower;

(vi) Remove the Temporary Earth Bond from the old earthwire [applied in (ii) above] and apply a Running Earth Bond to the new earthwire adjacent to the tensioner (Fig. 6);





(vii) The catch-off rigs shall only be removed from the earthwire when the Senior Authorised Person gives the instruction to do so. This instruction shall only be given once the Senior Authorised Person has carried out the appropriate checks and issued the Permit for Work to run the new earthwire.

1.7 Pulling New Earthwire

(i) Ensure all Temporary Earth Bonds throughout the section have been transferred from the old earthwire to the running block spigots;

(ii) Pull in new earthwire in accordance with Attachment B of PSSI 16;

(iii) When the new earthwire has been pulled into position, in preparation for sagging, apply Temporary Earth Bonds to the new earthwire at the towers where back-hanging will take place.

2. Sagging and Landing the New Earthwire

2.1 At the Back-Hang End Tension Tower

(i) Catch-off and back-hang the new earthwire;

(ii) If there is a conductor tail down the tower, usually present when installing OPGW, clip to tower steelwork using Approved metallic clamps;

(iii) De-rig the tower and the Equipotential Zone around the puller;

(iv) When the earthwire has been replaced, fit a new jumper and Permanent Earth Bonds. Remove the two Temporary Earth Bonds.





2.2 At Each Intermediate Tension Tower

(i) Apply Temporary Earth Bonds to the new earthwire on either side of the tower. Sag the new earthwire towards the back-hang end section tower and land it;

(ii) When the earthwire has been sagged on both sides of the tower, fit a new Permanent Earth Bond. Remove the Temporary Earth Bonds.

2.3 At the Sagging End Tension Tower

(i) Apply a Temporary Earth Bond to the new earthwire. Sag the new earthwire and land it;

(ii) If there is a conductor tail down the tower, usually present when installing OPGW, clip to tower steelwork using Approved metallic clamps;

(iii) De-rig the tower and the Equipotential Zone around the tensioner;

(iv) When the earthwire has been replaced on both sides of the tower, fit a new jumper and Permanent Earth Bond. Remove the two Temporary Earth Bonds.

2.4 At Each Suspension Tower in the Section

(i) After the earthwire is sagged and landed, transfer the Temporary Earth Bond from the running block spigot to the new earthwire. Clip-in the new earthwire in the suspension clamp assembly and fit the Permanent Earth Bond and dampers;

(ii) On completion remove the Temporary Earth Bond and running block from the tower.





ATTACHMENT A SCHEME 4 – INSTALLATION OF OPTICAL EARTHWIRE USING CRADLE BLOCK TECHNIQUE ON DOUBLE CIRCUIT 275/400KV OVERHEAD LINES WITH BOTH CIRCUITS LIVE

This Scheme has been withdrawn.





ATTACHMENT B – SAFETY FROM THE SYSTEM REQUIREMENTS FOR CONTINUOUS TENSION STRINGING OF EARTHWIRES UNDER SINGLE CIRCUIT OUTAGE CONDITIONS ON DOUBLE CIRCUIT 132/275/400KV OVERHEAD LINES

1. Scope

This Attachment details the Safety from the System requirements for the continuous tension stringing of earthwires, under single circuit outage conditions, on 132/275/400kV double circuit, overhead line towers designed pre 1991. Towers designed post 1991 shall be assessed as individual cases and appropriate working methods shall be determined and Approved. The Senior Authorised Person in charge shall determine if work on 132kV construction overhead lines and on tee-off towers, junction and terminal towers, certain large angle towers, high river crossings, towers of special construction and future designs, require special consideration and additional documented procedures. The raising or lowering of complete spans of earthwire from or to the ground and the handling of long tails of optical earthwire, are not covered by PSSI 16. These activities shall be undertaken in accordance with an Approved procedure. Appendix A of this Attachment is the Approved Checklist of Key Earthwire Pulling Activities.

2. Basic Safety Requirements

2.1 The senior location manager or his delegate shall consider the need to undertake the work with one circuit Live. Management considerations for work on earthwires in proximity to Live conductors are detailed in OPSAF-11-020 (MSP 2.9).

2.2 The Senior Authorised Person shall have sufficient technical knowledge and experience of the work to be undertaken, the techniques to be employed and the Safety from the System implications to enable him to make the necessary assessments and decisions for the planning of the work. He shall also issue the appropriate Safety Documents.

2.3 Prior to agreement that the work can be undertaken under single circuit outage conditions, the Senior Authorised Person referred to in 2.2 above shall be provided with, in the light of these safety requirements, an assessment of all sections of the overhead line. Taking into account that the new earthwire may require special considerations, e.g. optical earthwire, the Senior Authorised Person shall identify those towers or sections requiring special working arrangements, the requirements for double circuit outages or any restrictions on the positioning of plant or on the equipment to be used for the work.

2.4 A survey shall be carried out to assess the integrity of the old earthwire having regard to the mechanical stresses that can be imposed during the tension stringing process. This shall take into account the age of the earthwire, type, manufacturer, environmental aspects, known history of abnormal mechanical loading, damage and repairs, and the position and type of mid-span joints, repair-sleeves, displaced dampers and bird flight deflectors. Particular note should be taken of the condition of the earthwire at clamping positions. Should conductor corrosion be a serious concern, then a more detailed assessment shall be carried out. The results of the survey shall be documented and passed to the potential Contractors.

2.5 Prior to installing earthwires over roads, motorways, railways, navigable waterways or power lines, the Senior Authorised Person shall satisfy himself that all necessary precautions have been taken and that the Appointed Wiring Observer is aware of all such requirements.





2.6 The Senior Authorised Person, and the Appointed Wiring Observer involved in the field implementation of these safety requirements, shall have access to the Contractor's Method Statements and Project Quality Plan.

2.7 The Senior Authorised Person shall, prior to issuing the Safety Document, prepare a Checklist of Key Earthwire Pulling Activities (Appendix A) and each activity shall be signed and dated.

3. Basic Requirements to Safeguard Personnel

3.1 Earth Bonding

(i) At substation terminal towers the integrity of the earth connection to the substation earth mat shall be checked prior to the work commencing. If this is found to be defective or missing, a permanent repair shall be made before continuity of the earthwire is broken;

(ii) The integrity of the Permanent Earth Bonds on the earthwire shall be checked at the nearest towers on each side of the sections to be restrung, and on the earthwire that will not be disconnected on the tension towers at each end of the sections to be restrung;

(iii) To protect the operator of the tensioner, and the operator of the puller and personnel working on the reel winders, drums and associated equipment, against the effects of any rise in potential of the machines and equipment in respect to the ground they are standing on, an equipotential environment shall be provided. This shall be in accordance with Attachment B to PSSI 4. Access to the machines, operators, other personnel and equipment in the Equipotential Zones shall also be controlled in accordance with Attachment B to PSSI 4.

When the earthwire is square rigged up the tower at puller or tensioner positions, the outer perimeter of the Equipotential Zone shall, where reasonably practicable, extend to the tower such that it prevents access to the earthwire between the machine and the tower.

3.2 Drain Earths

(i) Drain Earths shall be fitted to all phase conductors on the Isolated and Earthed circuit at all towers in the section to be worked on and at the nearest towers on each side of the section. The Drain Earths shall remain in position for the duration of the work in the section;

(ii) Work shall not be undertaken on the phase conductors, insulators or associated fittings in the sections being worked on unless the earthwire is tensioned and permanently made off at both ends and electrically bonded to the towers in the section, thus ensuring earthwire continuity throughout the route;

(iii) No work that could possibly affect the mechanical integrity of the earthwire shall take place unless the phase wires of the Isolated and Earthed circuit are continuous between the towers either side of the section to be pulled and Drain Earths are fitted in accordance with 3.2 (i) above;

(iv) Prior to use, Drain Earths shall be inspected, with particular reference to the contact faces of the line end clamps, to ensure low impedance connections between the conductors and the tower steelwork;

(v) The earth continuity of the earthwire shall be maintained at all times during the restringing operation. This can be achieved by adopting the principles contained in the Earth Bonding Schemes in Attachment A of PSSI 16 and 3.2 (i) above.





3.3 Engineering Considerations

(i) Continuous tension stringing relies upon a secure mechanical connection between the old and new conductors and at other positions where conductor has been cut and jointed. Consideration shall be given to the type and condition of the conductors being connected and a decision taken as to whether and how a secure mechanical connection can be made. The method proposed shall include a Quality Assurance Procedure for the condition of the components used;

(ii) All joints shall be made by a jointer, specifically trained for this task and nominated in writing by the Contractor;

(iii) Any damage deemed as non-prohibitive to tension stringing found on the existing earthwire shall be securely taped over using high visibility reinforcing tape;

(iv) The work associated with the tension stringing of the earthwire shall not overload the supporting towers. Where necessary specialist advice shall be obtained;

(v) The Senior Authorised Person shall obtain confirmation from the Contractor that he has designed and positioned any scaffolding, self-supporting systems or Skycradles such as to be effective for the purpose. Tension shall not be released in any section until the Senior Authorised Person has been satisfied that appropriate measures have been taken in this respect;

(vi) The Senior Authorised Person shall agree the positioning of machinery and equipment to ensure that Safety Distance is maintained between the erection equipment or earthwire and the Live circuit. The positioning shall be arranged such that the operators of the puller and tensioner have a clear view, terrain permitting, into the sections being restrung;

(vii) All machinery and equipment to be used shall be suitable for the work and be appropriately maintained. The Contractor shall have available on site all documented information necessary to ensure the correct and safe use of the equipment. The Contractor's methods of work shall ensure that the equipment, particularly the swivels used in the joints between old and new conductor, are not subjected to excessive loads by severe bending. The Contractor's Project Quality Plan and Method Statements shall ensure that only equipment fit for the purpose is used and any faulty equipment is immediately withdrawn from use and quarantined;

(viii) When failure of a component, e.g. a running block or means of attachment at angle tower peaks, could allow the earthwire to move towards the Live circuit, the method of working shall ensure that, in the event of such a failure, the earthwire is restrained and Safety Distance is not infringed;

(ix) The method of work shall ensure that the earthwire does not run uncontrolled off the drum, thereby causing loss of tension at the tensioning machine;

(x) Before personnel leave site the earthwire section shall be pulled through and brought to approximately normal erection tension and clamped-in at appropriate towers to prevent excessive sags appearing.

When, due to unforeseen circumstances, this cannot be achieved, the earthwire shall as a minimum be tensioned, to a position where, under all conditions, Safety Distance from the phase conductors will not be infringed. It shall be clamped at appropriate towers, specified by the Senior Authorised Person to minimise the dependence on the temporary joints and the tensioner/puller machines and to prevent excessive sags;

(xi) All earthwire jointing shall be carried out without lowering the complete span of earthwire to the ground;





(xii) Subject to the exceptions in this paragraph, the stringing tension of the earthwire shall be kept as low as possible whilst ensuring the earthwire does not sag below the top phase conductors in the longest span in the section. The only permitted exceptions are that the sag may be allowed to drop below the top phase conductors in order to avoid exceeding the safe working load of any components or when a temporary joint, mid-span joint or repair sleeve is passing through a block at a large angle, tension tower.

Close attention shall be given to weather conditions in which conductor movement may result in Safety Distance to the Live circuit being infringed (see 3.6);

(xiii) The Contractor shall only use equipment that meets the following criteria and the Contractor’s engineer shall confirm this immediately prior to the restringing work by signing appropriate sections of the Checklist of Key Earthwire Pulling Activities Form (Appendix A).

The restringing equipment is suitable for the conductor being pulled;

Pulling tensions and overload device settings are compatible with the types of conductor involved;

The overload device setting does not exceed the safe working load of any component in the earthwire pulling system;

The equipment has been properly maintained and overload device settings have been checked.

(xiv) During restringing the running tension shall be indicated by instruments on the tensioner/puller machines. The required pulling tension shall be carefully controlled and the overload prevention device shall be in service;

(xv) The Senior Authorised Person shall agree the positions of the puller and tensioner;

(xvi) The handling of long tails of earthwire, not captive within the body of the tower, shall be carried out under a documented procedure;

(xvii) During the tension stringing operation, the earthwire and each running block shall be continuously monitored by trained staff, using binoculars if necessary, in communication with the tensioner/puller operators. If damaged earthwire, earthwire joints or repair sleeves are to be pulled through the running blocks, the puller operator shall be advised of the progress of the obstruction and pulling speed reduced as necessary.

3.4 Delayed Auto Reclose Equipment

(i) Before tension stringing commences or re-commences the Appointed Wiring Observer shall request the Control Person to switch out the Delayed Auto Reclose (DAR) equipment on the Live circuit. At the end of the restringing the DAR may be restored. This will be carried out and recorded in accordance with local procedures. In the event of the circuit tripping during the work the Control Person shall not reclose the circuit until he has obtained the agreement of the Appointed Wiring Observer on site.

3.5 Supervision and Competency of Staff

(i) The Contractor carrying out the tension stringing shall implement a satisfactory system of supervision which identifies the Person in charge of the work and the responsibilities of all other staff. The Authorised Person in charge of the pulling activities shall be nominated by the Contractor and named on the Checklist of Key Earthwire Pulling Activities Form (Appendix A);





(ii) The method of work shall be agreed by the Senior Authorised Person. He shall be satisfied that all appropriate measures to maintain Safety from the System are applied. General Safety is the responsibility of the Contractor engaged to carry out the work;

(iii) Earthwire tension stringing shall not proceed until the appropriate Permit for Work has been issued and the Checklist of Key Earthwire Pulling Activities Form (Appendix A) has been completed to the satisfaction of the Senior Authorised Person;

(iv) The Appointed Wiring Observer shall be present in the section to be worked on with his attention dedicated to the task. He shall not, in any sense, exercise supervision of the work, the arrangements for which are the responsibility of the Contractor;

(v) Persons engaged in work under this Attachment shall be suitably authorised, and trained and instructed by the Contractor, to ensure that they understand the safety and emergency procedures which are relevant to their work and that the work shall be done in accordance with the instructions and rules which have been laid down;

(vi) The Contractor shall provide The Company with documentary evidence that all his staff employed on this work have been assessed and nominated by his management as being competent for this specific work.

3.6 Weather Conditions

(i) Prior to work under this Attachment, the Appointed Wiring Observer shall ascertain the forecast on wind speed and lightning risk. The Control Person shall inform the Appointed Wiring Observer using the communication channel [see 3.7 (ii)] of any change in lightning risk or other weather condition which could adversely affect the work;

(ii) Work shall not commence or shall be stopped if the weather conditions are such that conductor movement could cause the Safety Distance to be infringed if conductor tension was lost during the stringing. Work shall not proceed if the wind speed is 15 mph or more, measured at a height of 10 metres above ground level;

(iii) In the event of, or the near approach of, a lightning storm, all work on the earthwire shall cease immediately. The Control Person may request the Appointed Wiring Observer to suspend all work in order that the DAR can be restored on the Live circuit for the duration of the storm or until such time as it is agreed work can resume. The Appointed Wiring Observer shall inform the Working Party and the Senior Authorised Person and confirm to the Control Person that all personnel are clear. Personnel shall remain well clear of the overhead line and the stringing equipment whilst a lightning storm is in the area;

(iv) Work shall be discontinued if fog or poor visibility prevents the Appointed Wiring Observer, or other observers positioned at every tower, from fulfilling their role.

3.7 Communications and Control

(i) An effective communication system shall be used by the Contractor during the stringing operations;

(ii) The Appointed Wiring Observer shall ensure that effective communication is established and maintained between the site and the Control Person;

(iii) Immediately before the stringing operation is commenced or re-commenced following a suspension the communication system shall be checked and the test recorded on the Checklist of Key Earthwire Pulling Activities Form (Appendix A), by the Appointed Wiring Observer. If work spans more than one day, the communication system shall be checked each day immediately before the start of work and recorded again by the Appointed Wiring Observer. Tension stringing shall be stopped immediately if the communication system becomes defective.





3.8 General Precautions

(i) During the tension stringing process personnel shall not be positioned underneath the earthwire being restrung;

(ii) During the tension stringing process, personnel positioned on the tower shall retreat to a safe position before the wire starts moving. The safe position shall be agreed with the Senior Authorised Person;

(iii) Access into the work area by people, vehicles, farm machinery, animals etc. shall be effectively controlled. Any unprotected access tracks shall be closely observed.

3.9 Emergency Procedures

(i) In the event of an unplanned action whereby the earthwire or any other equipment or material infringes or may infringe Safety Distance the Appointed Wiring Observer shall immediately arrange for the Live circuit to be switched out by the Control Person. When it has been confirmed that the Live circuit has been switched out, the Appointed Wiring Observer shall contact the Senior Authorised Person in order to recover the situation;

(ii) The senior location manager or his delegate shall have an Emergency Plan which caters for liaison with all other Utilities, Emergency Services, and the Control Person;

(iii) The Contractor shall have a written on-site Emergency Plan and shall instruct all his staff in the actions to be taken should the earthwire or any other equipment or material come within Safety Distance of the Live circuit. The plan shall include the following:

How Persons shall be withdrawn safely to a safe position;

How the immediate area shall be secured and controlled to prevent unauthorised access;

Details for the senior location manager or his delegate to liaise with all other Utilities, Emergency Services, and the Control Person;

The stipulations in 3.9 (i) above.

(iv) The Senior Authorised Person shall assess the situation and, if necessary, issue a Permit for Work for the activities associated with the recovery work. The recovery work shall only commence once this Permit for Work (if necessary) has been issued.





APPENDIX A: CHECKLIST OF KEY EARTHWIRE PULLING ACTIVITIES FORM

Route: ………………………… Tower Numbers: ........................................ Isolated and Earthed Circuit: ………………………….............................................................................................. Circuit Colours: ………………………….......................

Print Sign Time Date

Senior Authorised Person

Appointed Wiring Observer

Permit for Work recipient

CONTROL MEASURE TIME SIGNATURE

1 Suitable local and long term weather forecast

Suitable wind speed and direction measured at Location

Suitable visibility for activities

2 Earthing applied in accordance with Permit for Work

3 All towers being monitored by trained & Authorised Persons

All Authorised Persons fully understand their roles

Arrangements in place to control all traffic at unprotected

crossings

4 Only work associated with pulling activities to take place

All Permit for Work recipients have signed below

acknowledging the Permit for Work recipient in charge of the

earthwire pull

5 Equipotential Zones checked by SAP or SAP delegate

Local communications system suitable and operational

Puller and tensioner settings checked

6

Control Person contacted for:

Establishment of communications with Appointed Wiring

Observer

DAR on adjacent circuit switched out of service

Lightning risk level and weather warnings

7 Senior location manager or delegate informed of pull by SAP

8 All staff aware of emergency plan and procedures

9 Operation start time – tension released

Operation end time – conductor secured

10 Control Person informed of completion for restoration of DAR

All Authorised Persons in receipt of a Permit for Work for the section being worked on confirm that they and

all members of their Working Parties:

1. Have been informed of the appointment of the Permit for Work recipient in control of the earthwire pull.

2. Agree that only work under the Permit for Work for the earthwire pull shall be undertaken.

Name PFW No. Signature Date/Time