Energy

Networks

Association

Link Boxes and Cable

Pits Working GroupPaul JewellLink Boxes & Cable Pits Working Group Chairman

The Voice of the Networks

2 The Voice of the Networks

• Aim

• The aim of this working group is to provide a forum for ENA Members to review and harmonise current standards of asset management for underground LV link boxes and cable pits ensuring that they are designed and built to an appropriate standard and are adequately maintained throughout their life span. It also aims to ensure the health and safety of employees and the public by developing agreed high level principles for companies to consider when carrying out their risk assessments.

Terms of Reference

3 The Voice of the Networks

• A search engine search of “exploding pavement”

Background - Media Interest

4 The Voice of the Networks

• Failures appeared to focus on UKPN areas, as the news reports show

• Events were actually reported across the whole of the UK

• Events broadly followed LDB populations and LV network length

• Taking 2012 as an example:

Background

DNO 2012 Disruptive Failures

Electricity North West 7

Northern Powergrid 0

SP Energy Networks 4

SSE Power Distribution 0

UK Power Networks 27

Western Power Distribution 8

5 The Voice of the Networks

• The 2012 figures showed an increase in failures across the UK

• Failure rates as a percentage of population were relatively low but heading in the wrong direction

• The HSE were looking for an industry wide position

Background

20

12

0

0.1

0.2

0.3

0.4

0.5

0.6

2010 2011 2012 2013 2014 2015 2016 2017

Combined No of Falures (all) / Population (%)

6 The Voice of the Networks

• The UK treatment of link boxes at that time was mixed

• DNOs were adopting varying approaches to inspection and maintenance

• DNOs had not identified the assets as creating a significant issue

• Some initial debate about whether this was an ENA Safety Issue or and ENA Networks Issue – which high level group should own the task?

Background

7 The Voice of the Networks

• The Task Group was formed to respond to the situation that was developing and to address the HSE concerns

• Actions undertaken by the group included:

– Risk Assessment of LDBs with regard to public safety

– Management of assets within DNOs, taking best practice of DNOs

– First UK wide database of assets and failures to help advise on management

– Revision of the ENA specification for LDBs

Task Group

8 The Voice of the Networks

• One of the key requirements was the mitigation of risk to the public for a DNO asset which is generally placed in pavements

• Following a competitive tender process, EDIF ERA selected to complete a risk assessment

• The risk assessment included a review of mitigation measures in use by DNOs (blankets, locational risk, link tightening)

• The risk assessment balanced these mitigations against an assessment of reasonable investment using HSE guidelines to reduce risk to public

• The risk assessment fed into the ENA SHE position paper

Risk Assessment

9 The Voice of the Networks

• SHE position paper is being used to set an industry wide approach

• Management techniques include a mix of:

• Locational Risk Rating

• Increased maintenance frequencies

• Mitigation products such as protection blankets

• Link tightening checks

• SHE Position Paper 08 “Management of

Link Boxes and Cable Pits on LV

Distribution Networks”

Management of Assets

10 The Voice of the Networks

• All DNOs contributing to a single database which includes details for the period from the beginning of DPCR5 (2010)

• Details are taken from Ofgem RRP tables and ESQCR Regulation 31 reporting, so most of the data is already publicly available

• The database was used as a starting point for the Risk Assessment

• The database has helped DNOs work out how their individual performance fits within the UK

• The DNOs add new data every Six Months (Mar/Sep)

Database of assets and failures

11 The Voice of the Networks

• Current ENA Technical Specification (TS 09-23) is limited and relates mainly to electrical characteristics

• Failure mitigation is not covered

• Installation procedures are not covered, we have a tight technical specification but do not give requirements for lifting & handling and reinstatement

• Review is underway through the ENA Standard Leaders Group

Revision of ENA Specification

12 The Voice of the Networks

• All DNOs have added their own requirements to the specification

• All UK link box manufacturers have jointly helped create a practical specification which addresses the requirements

• Items learnt from the risk assessment have been added to the specification

• There is a new cantilever load test to help with resilience to installation problems

• ENA Specification is due in Summer of 2017

Revision of ENA Specification

13 The Voice of the Networks

• A lot of the background work is now done, the group is moving towards a monitoring phase

• Collaboration across the DNOs has strengthened our decisions

• We have assessed the risk and introduced suitable mitigations at all levels, from design through installation to management

• The UK is in a better position with regard to the management of Link Boxes

Summary