/ UK Power Networks / DSR 01 010
v6.0

Work in Live Substations – Safe Zones of Work

Owner
Name / Peter Vujanic
Title / Head of Health and Safety
Signature
Date / 01 May 2016
Authoriser
Name / Dudley Sparks
Title / Operational Safety Manager
Signature
Date / 01 May 2016

This document forms part of the UK Power Networks Integrated Management System and compliance with its requirements is mandatory. Departure from these requirements may only be taken with the written approval of the above authoriser.

Revision Record
Version number / 6.0 / What has changed?
Document reviewed minor word changes to s8 for clarity.
Why has it changed?
Re issue of DSRs
Date published / 01/05/2016
Next review date / 01/05/2019
Prepared by / C Shackell
Version number / 5.0 / What has changed?
Owner and Authoriser updated. Stores codes added in Appendix 1 where applicable.
Why has it changed?
Date published / 07/08/2014
Next review date / 06/08/2017
Prepared by / N. Saunders
Version number / 4.1 / What has changed?
Minor word changes
Why has it changed?
Document reviewed
Date published / 16/05/2012
Next review date / 15/08/2014
Prepared by / N. Saunders
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Contents

1.0Introduction and Purpose

2.0Scope

3.0Objective

4.0References

5.0Definitions

6.0Responsibilities

7.0Records

8.0Process Detail

1.0Introduction and Purpose

This procedure gives further guidance to the setting out of work zones in High Voltage (HV) substations with exposed Live Conductors.

The Distribution Safety Rule (DSR) 4.5.1 specifies how a zone of work shall be identified and delineated. The rule calls for the use of approved barriers or chains to be used.

Each of the distribution companies and National Grid (NG) had evolved a different method of doing this and the Health and Safety Executive (HSE) identified some risk of confusion where work is being done on shared sites. The Energy Networks Association (ENA) produced a recommended barrier and roping system and UK Power Networks has implemented a system that is consistent with the ENA recommendations. It is supplemented by further requirements, where these have not been catered for in the ENA recommendations (e.g. for Limitation of Access).

UK Power Networks (UKPN) has shared sites with NG. The NG standard (NSI6) is extremely comprehensive and complex and designed to cover the very complex situations that NG will encounter.

Some network operators may not have adopted the ENA recommendations. Therefore all UKPN staff must be aware that they may encounter different barrier and roping systems on shared sites.

2.0Scope

This document applies to all UKPN Licence areas and private networks that are owned or managed by UKPN.

3.0Objective

To define the approved barrier and roping system used in UKPN, that delineates the temporary zone of work required by DSR Rule 4.5.1.

To ensure that people working in UKPN substations with exposed HV live conductors can clearly understand where they are to work.

4.0References

DSR / Distribution Safety Rules
ENA / Energy Networks Association, position paper 01
NRSWA / New roads and street works act.

5.0Definitions

DSR Section 2 / Words in bold type are defined in the DSRs

6.0Responsibilities

It is the responsibility of all UKPN employees and Managers and contractors working for UKPN, to comply with the requirements of this procedure.

7.0Records

An on-site record, in the form of a list as detailed in appendix A, will be kept of the barrier and chain equipment.

8.0Process Detail

8.1Compared to other areas in the electricity supply industry, substation compounds with live exposed HV conductors have been shown to have some of the highest risks of major injury or death.

8.2Open compound type substations contain many pieces of apparatus that are identical in make and version. When work is done under a permit to work, often most of the apparatus remains live and a small part of the substation is made dead and earthed in accordance with DSR 4.1.

8.3DSR 4.5 defines how work shall be managed by the Senior Authorised Person(SAP), to ensure that all persons working in the substation understand what apparatus they are to work on and also under which safety document they are to work.

The three safety documents are:

  • Permit to Work (PTW)
    All apparatus and conductors detailed on the document are dead and earthed and shall remain so for the duration of the work.
  • Sanction for Test (SFT)
    Apparatus and conductors have been made dead and have been earthed initially but may become live at any time with dangerous test voltages.
  • Limitation of Access (LOA)
    Apparatus and conductors have not been made dead and have not been earthed. Safety is ensured by maintaining safe working clearances to the live conductors.

8.4It is a requirement that a suitably authorised person shall issue the safety document for work in a substation compound containing live exposed HV conductors.

8.5This Document provides a different demarcation system for each case. The purpose of this is to give sufficient visual markers, to avoid confusion.

8.6The different demarcation systems are not a substitute for the Senior Authorised safetydocument issuer and the recipient of the safety document, ensuring that members of the working party understand the nature of the work and the risks and dangers that are involved. The demarcation systems are an important additional safety feature whose purpose is to aid the safe management of the work site.

8.7Marking the Work Zone and Access Route

8.7.1Barrier and chain systems are not designed to be a physical barrier to stop intruders gaining access to the apparatus or to keep members of the working party in the work zone. The systems are designed to be a marker or indicator of where the work zone is. However, at no time should any person climb over the barrier chain or any part of the substation permanent enclosure to access the work zone. Authorised entry must always be through the designated entrance.

8.7.2To ensure that members of the working party can clearly know whether they are inside the work zone, markers shall be placed inside the work zone (PTW and SFT only).

8.7.3All apparatus adjacent to the outside of the work zone shall be clearly marked with Danger Notices. The notices shall be placed to be visible to anyone approaching the zone and anyone inside the zone.

8.7.4If the work zone can sensibly be extended to within one metre of the gates of the substation compound without compromising safety, then this should be done to limit movement of people in the compound. The remaining gap between the gates and the start of the work zone will allow others access to the other parts of the compound that are outside of the demarcated work zone.

8.7.5If the work zone cannot be sensibly extended to within one metre of the gates of the compound, then an access route may be marked out, if it is necessary to prevent Danger.It is important that all people working on the site understand that this marked access route may pass close to, or under live conductors and that the safety rules 4.5.4 and 4.5.5 regarding movements of long objects etc. must be complied with.

8.7.6The entrance to the work zone will be formed by two purple coloured cones. The rest of the access route shall be indicated by two rows of yellow cones fitted with a white sleeve with black lettering saying ‘ACCESS ROUTE’. The width of the entrance and access route shall not be more than 1m wide for pedestrians. If vehicular or plant access is required, the entrance may be widened but should not normally exceed 1.5m. A notice shall be placed at the entrance showing who the safety document holder is and how to contact them.

In the case of a Permit to Work, the notice will state that no person shall enter the work zone whilst work is taking place, until they have made contact with the safety document holder and been fully inducted into the work.

In the case of a Sanction for Test, the notice will state ‘no entry without the permission of the safety document holder as identified below’.

8.7.7If the access route passes under live exposed conductors, then the warning notice for overhead live equipment notice shall be displayed at the beginning of the route for access and end of the route for egress, so that it can clearly be seen when travelling along the route in either direction. In addition, danger noticesshall be attached to apparatus containing live conductors and conductor supports along and adjacent to the access route.

8.8General Specification (PTW and SFT only)

8.8.1The barrier will be a yellow and black plastic chain with closed links.

8.8.2As the ground will probably contain cables and earth conductors, any supports for the barrier will be self-supporting and not penetrate the ground

8.8.3The supports will be yellow plastic cones. They will be weighted at the base with facility to add weight where required. The supports will have a slot moulded into the top to attach the chain.

8.8.4When erected, the cones shall be sufficiently close so that the chain is at least 500mm. above ground level.

8.9Permit to Work Zone

Perimeter boundary: / Yellow cones.
Yellow and black chain.
Entrance: / Zone will have an open entrance, denoted by two purple cones leading to the entrance.
Access notice to be positioned next to the entrance. Blue text on white background.
Inside the zone: / Yellow cones with green sleeves.
Live conductors over work area notice (if required). Black text on yellow background (additional signs made of a magnetic material for ease of fixing, may also be used).

Fig.1 Ideal layout showing cones and chain for a PTWzone.

8.9.1Figure 1 shows an idealised layout of the cones and chain for a PTW zone. It is the duty of the Senior Authorised Person to arrange the chain and cones to make it as clear as possible where the work zone is.

8.9.2The DSR expressly forbids attaching the chain to any structure supporting electrical apparatus or conductors. It should be obvious that if the chain was attached to a structure, then it is not clear if the structure is included or excluded from the work zone.

Where possible the zone shall be arranged so that no structure carrying Live exposed conductors is within the zone. This includes any conductors that over sail the work zone. If this is not possible, then the structure will be clearly marked with DangerNotices and Danger Do Not Climb bands (additional signs for example, made of a magnetic material for ease of fixing may also be used).

In addition, yellow signs warning of live conductors over work area shall be placed at the entrance to the zone.

It is permitted to attach the chain to the earthed fence surrounding the substation compound.

8.9.3The area shall also be adequately lit.

8.10Sanction for Test zone

Perimeter boundary: / Yellow cones.
Yellow and black chain.
Entrance: / Zone entrance will be closed by yellow and black chain. The entrance will be denoted by two purple cones leading to the entrance. Qualified ‘No entry’ sign. White text on red background.
Inside the zone: / Yellow cones with red sleeve having white text denoting ‘Test Area’. Live conductors over work area notice (if required). Black text on yellow background.

Fig.2 Ideal layout showing cones and chain for a SFT zone.

8.11Working and Access Clearances

8.11.1The work zone barrier shall be sited to comply with the requirements of section 4.5 of the Distribution Safety Rules and establish the necessary Working and Access Clearances.

8.11.2The movement of materials and tools etc., through the access route, shall be controlled to comply with the requirements of section 4 of the DSR.

8.12Management of Work under a PTW or SFT

8.12.1Where physical demarcation is to be used this must be:-

  • Erected after completion of all safety precautions and before any safety document is issued
  • Removed after the clearance of the safety document(s).

8.12.2The safety document shall be issued as defined in section 4 of the DSR by theSenior Authorised Person.

Once the safety document has been issued, the issuer shall satisfy himself that the work is being done safely. The work shall be visited at regular intervals by the issuer, or a person with equivalent authorisation and knowledge of the job. For extended periods of work, the time between visits shall not exceed three days, whenever actual work is in progress.

8.12.3For compounds or enclosures where there is only one item of equipment, it will not be necessary to deploy the yellow cones and chain to mark out the work zone. All other requirements must be implemented e.g. signs at work zone entrance, cones with appropriate sleeves inside the zone to indicate what type of zone has been established, etc.

As there must only be one entrance to a demarcated zone, if there is more than one gate or door to this compound or enclosure, then an appropriate Do Not Enter, This is a PTW/SFT Zone warning sign must be place at these other gates or doors.

8.13Limitation of Access Work Zone

8.13.1General

A limitation of access is a safety document that is defined in the DSR. It is used to explain how a person can work safely in the vicinity of live exposed conductors and other places in substations.

The equipment that presents danger will not have been made safe in accordance with section 4.1 of the DSR. Instead, safety is achieved by staying a safe distance away from the conductors.

This safe distance should normally be much greater than the working and access clearances defined in the DSR.

Within a substation (s/s) that has exposed live HV conductors the LOA is often issued to allow work at ground level. The work may or may not include excavations.

It is permissible to write a LOA that simply explains where the work is to be done and where the dangers are.

For some work, it might be desirable to limit the access of the person, by erecting a barrier. It is possible that a person, who was previously working in a PTW zone one day, might just mistakenly believe that the apparatus inside the LOA zone that he is currently working in is dead!

Many of the people who will work under a LOA will be contractors, whose main work is non electrical. However well these people are trained, they will not have the same level of practical experience as people whose work is predominantly electrical. The awareness that an experienced person develops will not be there.

For this reason, it is imperative that any work under a LOA must be carefully managed. In fact work under a LOA should attract a higher level of management and supervision than work under a PTW. Traditionally this has not been the case and work under a LOA is looked on as being less of a management problem than most.

8.13.2If the LOA zone is all the Substation

Where the LOA is written to allow access to the whole s/s, no specific barrier systems need be erected. The recipient of the LOA will be issued with the document on site. Furthermore, the recipient is required to show the issuer that he understands the document and how the work is to be done. The recipient will demonstrate that he understands the dangers within the s/s and that any safety precautions to prevent contact with live exposed conductors are fully understood.

The issuer will also satisfy himself that any other members of the working party have sufficient understanding of the work and the dangers. The issuer will check that all members of the working party can demonstrate competence in the work activity.

If there is equipment in the s/s that has a known danger due to catastrophic failure, then a LOA will not be issued covering the whole s/s.

The issuer will satisfy himself that the recipient understands the work and that it is practical to do the work without infringing sensible safety clearances. The exact clearances must be determined by the issuer, taking into account:

  • The nature of the work
  • The arrangement of the conductors
  • The experience and competence of the recipient and the other members of the working party

The issuer, or a person with at least the same level of authorisation and knowledge of the work, will visit the site during the work, to ensure that the safety precautions are being complied with. Where the work takes place over an extended period, the period of time between visits shall not exceed three days, whenever actual work is in progress.