asset category – electricity, safety, quality and...

Asset Category – Electricity, Safety, Quality and Continuity RegulationsCompliance LPN

Asset Stewardship Report 2013

Jeremy Wright

Asset Stewardship Report 2013 Working draft v0.1 ESQCR Compliance Version 2.6

UK Power Networks (Operations) Limited. Registered in England and Wales. Registered No. 3870728. Registered Office: Newington House, 237 Southwark Bridge Road, London, SE1 6NP 2

Approved by Richard Wakelen

Approved date 06.06.2013

Document Management and Governance by Victoria Patrick

Document History

Version Date Details Prepared by

1.0 10/01/2013 Template issued to Asset Management PA / Strategy &

Regulation

1.1 22/02/2013 UKPN branded, cover sheet added and

document history page moved

Lee Strachan

1.2 22/03/2013 B&V updated draft Paul Harmer

1.3 27/03/2013 Updated for silver status submission Jeremy Wright

1.4 03/04/2013 Updates for Gold Status Jeremy Wright

1.5 03/04/2013 Approved at Gold Status Richard Wakelen

1.6 09/05/2013 Approved at Gold no queries submitted Richard Wakelen

1.7 16/05/2013 Updates following meeting with HSE Jeremy Wright

1.8 16/05/2013 Approved at Gold Richard Wakelen

1.9 05/06/2013 Update of document following discussion

with IW (PA consulting)

Jeremy Wright

2.0 06.06.2013 Approval at Platinum Jeremy Wright

2.1 06.06.2013 Approved at Platinum Richard Wakelen

2.2 10/06/2013 Platinum Updates Jeremy Wright

2.3 14.06.2013 Barry’s comments addressed and sent for

review

Victoria Patrick

2.4 23.06.2013 Additional comments from Barry now

complted and re issued for review

Victoria Patrick

2.5

2.6



Contents 1.0 Executive Summary LPN ESQCR Compliance ........................................................... 5

1.1 Scope ..................................................................................................................... 5

1.2 Investment Strategy ................................................................................................ 5

1.3 ED1 Proposals ........................................................................................................ 5

1.4 Innovation ............................................................................................................... 6

1.5 Risks and Opportunities .......................................................................................... 6

2.0 Description of LPN ESQCR Compliance focus areas ................................................. 7

3.0 Investment Drivers ..................................................................................................... 8

3.1 ESQC Regulations .................................................................................................. 8

3.2 Identifying Interventions required ............................................................................ 9

3.3 Intervention thresholds .......................................................................................... 10

3.4 Examples of non compliance ................................................................................ 11

3.5 Incidents and events ............................................................................................. 12

4.0 Asset Assessment .................................................................................................... 15

4.1 Asset Health ......................................................................................................... 15

4.2 Asset Criticality ..................................................................................................... 16

4.3 Network Risk ......................................................................................................... 17

4.4 Data Validation ..................................................................................................... 17

4.5 Data Verification ................................................................................................... 17

4.6 Data Completeness .............................................................................................. 18

5.0 Intervention policies .................................................................................................. 18

5.3 Interventions: Description of intervention options evaluated .................................. 18

5.4 Policies: selecting preferred interventions ............................................................. 19

6.0 Innovation ................................................................................................................. 20

7.0 ED1 Expenditure requirements for ESQCR Compliance .......................................... 30

7.1 Method .................................................................................................................. 30

7.2 Constructing the plan ............................................................................................ 30

7.3 Additional considerations ...................................................................................... 31

7.4 Asset volumes & expenditure ................................................................................ 31

7.5 Commentary ......................................................................................................... 36



1.0 Executive Summary LPN ESQCR Compliance

1.1 Scope

The Electricity Safety, Quality and Continuity Regulations 2002 (ESQCR) regulates quality

and supply continuity requirements as well as specifying safety standards. Compliance to

ESQCR is a statutory requirement for distribution network operators (DNO’s). UK Power

Networks (UKPN) has defined its company policies in accordance with ESQCR in order to

minimise risks to the public, staff and its contractors.

Increasing focus from a health and safety perspective has resulted in network

operatorshaving to ensure compliance with Government legislation. This document details

our proposed asset policy, practice and funding strategy during the ED1 period in order to

ensure ESQCR compliance in the following areas:

Signage for substations.

Cable pits – Inspection and risk management.

1.2 Investment Strategy

Safety compliance issues within LPN are identified through a defined periodic inspection of

assets. These compliance issues are prioritised through a risk framework based prioritisation

model and are resolved appropriately within pre-determined time schedules based on

severity and potential risk.

UK Power Networks’ investment strategy for ED1 has been set to comply with ESQCR in

order to minimise the risk to members of the public and employees.

1.3 ED1 Proposals

This document summarises the expenditure on ESQCR compliance related issues

concerning signage and cable pits during ED1. The average annual expenditure for cable

pits is increasing significantly in ED1 due to a review of the inspection and risk management

for cable pits following a recent incident where members of the public suffered burn

afflictions. Each of these will be explained in detail in later sections.



Expenditure Category

ED1 Total expenditure

DPCR5 Total expenditure

ED1 Annual average expenditure

DPCR5 Annual average expenditure

Signs £206,088 £53,856 £25,761 £10,771

Cable Pits £17,828,843

£6,259,949

£2,228,606

£1,564,987

Grand Total £18,034,931

£6,313,805

£2,254,367

£1,575,758

Table 1: LPN ESQCR expenditure summary for ED1

1.4 Innovation

UKPN has introduced a risk based approach to compliance management, which we believe

is an industry leading initiative in the way risk is minimised and compliance issues are

identified, prioritised and resolved efficiently. UKPN have developed a centralised risk

based prioritisation model to identify the priority of an asset defect on a scale of P1 to P5,

with P5 issues being the most urgent. This has been introduced for all asset types and was

developed in collaboration with Network Operations and external parties by developing asset

management strategies.

Standardised inspections and prioritised risk management strategies for cable pits are being

introduced as an industry leading initiative. UKPN are undertaking a complete evidence

based evaluation of cable pit risk management. Failure modes that can result in a disruptive

failure of a cable pit are being evaluated and corresponding risk mitigation strategies are

being developed. UKPN are designing several cable pit covers that can vent a gas build up

and help to prevent a cover from being expelled from the frame in the event of a disruptive

failure. Consequently, limiting the damage caused to property and also reducing the risk of

injury to members of the public.

1.5 Risks and Opportunities

Opportunity

Description of Risks / Opportunities Uncertainties

Opt-Emax Cover

A carriageway cover that could reduce

the severity of an injury where an arcing

disruptive fault would result in the cover

being ejected.

£1,355 expenditure per installation, whilst covers have been highlighted as potentially suitable mitigitations, they have



not being tested under arcing fault forces. Further analysis/testing is required before this cover can be a certain mitigation.

Clark Drain Cover A footway cover that could reduce the severity of an injury where an arcing disruptive fault would result in the cover being ejected.

£3,302 expenditure per installation. The cover has been specifically designed to vent, via spring hinges, under arcing fault pressures. However, the cover is yet to be tested under arcing fault forces and will require further analysis/testing before it is a certain mitigation.

Structural Science Composites Cover

A vented composite fibreglass cover with 12mm diameter vents over its surface (providing a vent area of ~10%). It has been developed with ConEdison and is the only product considered that has undertaken load tests on the underside and arc event simulation tests.

£1,145 expenditure per installation.

Risk Methodology The risk assessment will be used to prioritise the inspection programme and to identify Very High and High risk cable pits. Mitigations can then be applied to those pits in order to reduce the likelihood of a disruptive event and reduce the severity of injury to the public if a disruptive failure does occur.

The risk assessment is a desk based exercise. Some mitigation implementation is based on the results of a pilot study, which may not give an accurate representative of all cable pits in LPN.

Table 2: Risks and opportunities

2.0 Description of LPN ESQCR Compliance focus areas

ESQC regulations have implications throughout UKPN operations. The work required for

ESQCR compliance is covered in asset specific documents (e.g. substation trespass is

covered under the Civil justification document, increased safety patrols on high risk sites are

covered under the Inspections and Maintenance document). This section details our

proposed asset policy, practice and funding strategy in the ED1 period on ensuring ESQCR

compliance on signage and cable pits.

LPN has a network of 17,563 substations. Additionally, 47,748 cable pits are to be inspected

and monitored as part of ESQCR compliance. See Table 3.



Asset Class Asset Category Total

Site

Grid Substation Site 60

Primary Substation Site 147

Secondary Substation Site 17,356

Cable Pit Cable Pit 47,748

Grand Total 65,311

Table 3: LPN ESQCR focus areas

3.0 Investment Drivers

3.1 ESQC Regulations

The primary investment driver for compliance management is to minimise risk to the public

and staff at the lowest cost to customers. Additionally, there is the obligation to ensure

regulatory compliance with the safety aspects of the ESQC Regulations 2002.

London’s electricity network is primarily comprised of underground assets connected to

substations. Therefore, safety challenges faced by London are primarily related to risk

management of cable pits and substations.

Public safety risks are increased in the LPN region due to the close proximity of these assets

to densely populated areas and underground gas mains. This is illustrated by the occurance

of disruptive cable pit failures. These need to be managed with appropriate levels of

inspection and risk management with interventions made to ensure that risks to public safety

are managed, whilst ensuring that the interventions are reasonably practicable.

Additionally, incidents of substation trespassing and thefts are increasing, subsequently

highlighting the risks of potential injury to members of public in substations. These will have

to be mitigated by appropriate signage on all substations to notify the public about the risks

of potential electrical contact.

The ESQCR Compliance aspects covered in this document are:

1. Regulatory signage warning the public of the electrical hazards on site

(substation signs).

2. To ensure that the cable pits are inspected routinely and cable pit risks are

managed appropriately.



LPN inspectors are trained to identify and record ESQCR non compliance issues as part of

the inspection routine which will then be recorded into the Asset Register application.

Any non compliance identified through inspections will require resolution. Please refer to

Section 5 for specific details on different interventions carried by out UKPN to ensure

ESQCR compliance.

3.2 Identifying Interventions required

ESQCR compliance issues are identified during routine inspection of our assets. Inspection

frequencies are outlined in Engineering Maintenance Standard EMS 10-0002.

ESQCR compliance issues identified are recorded as a defect in the asset management

register ‘Ellipse’. UKPN use a risk framework based on a defect prioritisation model to

robustly manage and prioritise the defects. The prioritisation model considers the risk to

public safety, quality of supply, environmental risk and the ESQCR risk rating. This

prioritisation model and the defect management programme are detailed further in section 6.

Urgent ESQCR compliance issues are also reported to AIRLine. AIRLine is UKPN Accident

and Incident Reporting line. Any compliance issues that are considered as an immediate risk

to public safety must be reported to AIRLine. Through AIRLine an action is assigned to a

member of staff to investigate and risk assess the issue and arrange for resolution within an

appropriate risk based time scale.

Signage

The Substation Inspectors’ Handbook details the requirements for safety signage ensuring

full compliance with ESQCR.

Signage issues are identified, and where possible, rectified as part of the routine inspection

of our assets. Signage issues not rectified at the time of inspection are prioritised and

managed as part of the defect management programme.

Cable Pits

UKPN has developed a cable pit strategy, further described in section 6, which will identify

the interventions required on cable pits. All cable pits will be inspected, ESQCR risk

assessed and where required, suitable cost effective risk mitigations will be carried out. This

project has been launched following an internal investigation and review of a disruptive

failure of a cable pit in London in 2012 where three members of the public received burns.



This incident is detailed further in section 3.5.

3.3 Intervention thresholds

Signage (Substations) Signs will require replacement if they are vandalised, or found to be non compliant with

ESQCR and UKPN policy. Also, depending on the position of the sign, the expected life can

be reduced significantly due to ultra violet exposure, where ultimately, the signage is faded

by sunlight and will require replacement. Figure 1 in section 3.4 is a typical example of a

yellow danger of death sign which has faded due to prolonged exposure to direct sunlight.

Where possible, UKPN have reviewed the signage design with the supplier, in particular the

ownership sign on substations, to use a black pigment instead of colours as the black

pigment has a longer expected life span. Figure 4 shows the previous ownership signage

which has faded.

As mentioned previously, signage issues are rectified where possible at the time of

inspection to ensure maximum cost efficiency.

Cable Pits

As previously mentioned, UKPN has developed a cable pit strategy, detailed in section 6,

which will identify and detail interventions required on cable pits.

As part of the development of the strategy, 373 trial inspections were completed during

December 2012 in the London area. Information gathered from the inspections has been

analysed to develop the strategy moving forward. This includes collecting condition and

defect information, an ESQCR risk assessment, as well as possible risk mitigations where a

high risk or key risk is identified. Although the strategy is initially focussing on London where

the highest risks have been identified, the strategy is being implemented across all of

UKPN’s operational networks.

A project to identify cable pits and record them in the asset register (Ellipse) in LPN is

complete.



UKPN records ESQCR non compliance as defects in the asset register. Defect categories

exist to record any issues against cable pits. Currently, the defects and conditions measures

are being developed to record and monitor cable pit conditions.

The defects and mitigations are fed into the defect criticality model, this asigns the priorities

score and the target resolution time schedule for each defect.

3.4 Examples of non compliance

Signage Issues

The photos below outline a few examples of signage compliance.

Figure 1: Faded signage due to UV exposure Figure 2: Vandalised Sign with graffiti

Figure 3: Substation signage missing

Figure 4: Faded ownership details



Cable Pits:

The photos below outline a few examples of cable pit compliance issues. Figure 5 and 6

show the impact of a disruptive failure of a cable pit. This will be described in more detail

under section 3.5.

Figure 5: Footway disruption following a cable

failure

Figure 6: Status of the cable following failure

Figure 7: Poor condition ladder

Figure 8: Poor condition pavement cover

presenting a potential trip hazard

3.5 Incidents and events

As previously mentioned, AIRLine is the UKPN Accident and Incident Reporting line.

Compliance issues that are considered as an immediate risk to public safety must be

reported to AIRLine. All staff and contractors as well as members of the public can report

incidents to AIRLine through the customer call centre.

This section outlines the trends of incidents reported to AIRLine between 2010 and 2012 on

signage, overhead line issues and cable pits.



Signage:

Table 4 shows an increasing trend of signage issues reported to AIRLine. This is

predominantly as a result of increased awareness by all UKPN staff and contractors

following an audit on substation signage carried out in SPN in January 2012.

Table 4: Incorrect signage incidents reported to AIRLine

The audit focussed on the ESQCR requirement to display sufficient safety signs as well as

identification of ownership and location details. Compliance issues identified included faded,

vandalised and missing signage, as illustrated in Figures 1 - 4 of section 3.4.

Signs have been redesigned to avoid the use of colours, where possible, so as to reduce

fading. Internal signage audits continue to be carried out and dedicated briefing sessions

have been held with inspectors across all of UKPN. ESQCR signage requirements are also

included in team briefing sessions for all staff to ensure a wide audience can identify and

report ESQCR signage compliance issues. The simple message conveyed to staff is to ask

yourself - if you were the emergency services and arrived on site, could you contact the

owner of the site and readily provide location or an identification number for the site. This is

critical information required by the emergency services if an incident were to occur on the

site. Figure 9 displays the team brief communication.



SUBSTATION SIGNAGE Compliance Random inspections by the Health & Safety Executive at 6 Grid and Primary substation sites raised a concern as signs were either missing, inadequate, defaced or faded. This is not compliant with statutory regulations and UKPN EI 09-0019.

Graffiti should

be removed.

Danger of Death should

be bright yellow.

UKPN ownership

label faded.

Look out for incorrect signage and report to AIRline. Ask yourself, if you were the emergency services and arrived on site, could you contact the owner of the site (UKPN) and readily provide the location or an identification number for the site? This is critical information required by the emergency services if an incident were to occur on the site.

Every secondary gate

accessible by vehicles

has signage in this

format fitted.

Every main gate (the first one that

the emergency services arrive at)

has this sign fitted.

‘Danger of Death’ sign should be clean and bright yellow.

UKPN ownership & site location labels should be clear & clean.

Figure 9 : Team Brief communication following audit

Cable Pits:

Table 5 shows an increasing trend of cable pit disruptive failures in London area reported to

AIRLine.

Table 5: Cable pit disruptive failures



The investigation of a disruptive cable pit failure in May 2012 in LPN identified the root cause

for the disruptive failure as leaking gas which had filled the cable pit over a period of time so

that the atmosphere was at an explosive level. The recommendations from the investigation

included a full review of the cable pit strategy as inspection records were not readily

available. This initiated the launch of the development of the cable pit strategy project and

the capturing of all cable pits in Ellipse.

Another disruptive failure of a cable pit in November 2012 in LPN resulted in a member of

the public falling in to the pit and receiving injuries. It was not a deep pit but it has focussed

UK Power Networks to address this risk and research options to mitigate the risk. One option

is to fit a fall arrest grill under the cover.

4.0 Asset Assessment

4.1 Asset Health

Current outstanding non compliance issues in LPN are outlined below. UKPN has an

established defect rectification programme with the aim of reducing the outstanding defect

count to normal operating level by 2015. The defect management scope has been expanded

to include cable pit defects identified during inspection.The trial to capture data from cable pit

inspections and the resulting defects was completed in the final months of 2012.

The sample inspection of 373 cable pits was undertaken in LPN to assess and record asset

condition. The condition data collected indicates that 29.5% of cable pits had a defect which

would require some level of mitigation. See Table 6.

A new and improved defined inspection and maintenance regime has been developed to

minimise risk to members of the public.

Findings from the sample survey:

Pit condition and size varies significantly

Of the 373 pits inspected, 110 had at least one defect and 4 cable pits had more than

one

Six pits were found with gas present and were identified as having a key risk

Some defects, such as poor condition ladders, can be rectified at the time of

inspection, i.e. removal of the ladder

Breakdown of Defects Number of Defects % of Total Survey

Defect Lid 62 16.6%

Defect Cable Joint 2 0.5%



Imploded Joint 12 3.2%

Structural Defect 3 0.8%

Defect ladder (unsafe) 35 9.4%

Total Defects 114 30.6%

Number of Cable Pits with Defects 110 29.5%

Table 6: LPN Trial Inspection – Breakdown of Defects

4.2 Asset Criticality

UKPN developed a comprehensive defect prioritisation model to prioritise the defects

identified on the network and ensure they are dealt with the appropriate level of urgency.

Each of the defect categories were reviewed and assigned a risk score based on

o Regulatory Risk

o Safety Risk

o Environmental Risk

o Quality of Supply Risk

o Financial Risk

Regulatory, safety and environmental risk are assigned a higher weighting to ensure that

they are resolved as a priority.

The priority on a defect is not decided by the inspector but will be applied centrally though

the defect prioritisation model thereby ensuring strict control and governance on the process.

The model will rely on additional factors such as location risk, equipment risk of the asset

(safety, environmental, QoS and financial risk already assigned on the defect category) to

arrive at the overall priority. Once the priority is assigned, it will not be subject to change and

will have to be resolved as per the agreed resolution time standard.

Based on risk score, each defect category is assigned a priority from P5 to P1 which has a

designated resolution time schedule as shown in the table 7.



Defect Criticality Definition Resolution Time Schedule

P5 Critical < 3 months

P4 Urgent 3 – 12 months

P3 Required 12 – 24 months

P2 Medium 24 – 48 months

P1 Low During next maintenance, next visit

P0 - For information only

Table 7: Defect Criticality Definition and Resolution Time Schedule

4.3 Network Risk

The risk of an asset failing is a combination of the probability of failure (such as age and

duty) and the consequence of failure (such as network performance). Asset criticality

provides a measure of the consequence of failure and is evaluated in terms of the following

four primary criticality categories:

• Network Performance (PD monitoring, function, spares/obsolescence, licence area

and customer number)

• Safety (internal arc rated, arc extinction and ESQC risk level)

• Financial; opex (licence area, spares/obsolescence) and capex (voltage and licence

area)

• Environmental (site sensitivity, arc extinction, gas capacity and volume of oil).

In order to compare and combine category consequences, each consequence value is

equated to a monetary assessment. Once the average consequence of failure for a group

has been valued, it is necessary to define the criticality of an individual asset (for each

consequence category). The score for each consequence category is then added together

and converted to an Ofgem criticality index (C1-4) A detailed methodology for calculating the

criticality index can be found in ‘Commentary Document 15: Model Overview’.

4.4 Data Validation

The collection of the ESQCR risk asessement information and the cable condition data is still

being collated so minimal assessment is possible on the complete population of cable pits in

LPN.

4.5 Data Verification





LPN.

4.6 Data Completeness



LPN.

5.0 Intervention policies

5.3 Interventions: Description of intervention options evaluated

The following table outlines the issues and the remediation adopted for resolution.

Signage:

ESQCR compliance

issue

Compliance description Description of intervention options

Signs:

Provision of warning

signs for overhead line

structures and

substations

Replacement of defective and non-compliant signs

Cleaning of signs with graffiti / dirt where possible

Table 8: LPN – Interventions on signage

Cable Pits:

Interventions required on cable pits are still in the development phase. Below is a list of the

interventions which are being progressed and researched further.

ESQCR compliance issue

Compliance description

Description of intervention options



Cable Pits Risk mitigation on

cable pits

Report

Repair

Replace

Remove

Refer to section 6 for further details on intervention and mitigation strategies

Table 9: LPN – Interventions on cable pits

5.4 Policies: selecting preferred interventions

Each site will be risk assessed and the most cost effective intervention, if required, will be

applied. Intervention for specific compliance issues depend on a variety of factors, such as,

location and type of asset.



Figure 10 summarises the research to date on selecting preferred interventions for cable pit

risk management.

Figure 10: Decision tree on cable pit interventions

6.0 Innovation

Defect Management Program



UKPN launched the Defect Management Programme in September 2011 to review, prioritise

and resolve the defects identified during inspections.

A risk framework based defect prioritisation model has been implemented to prioritise and

ensure that the most critical issues are addressed as appropriate.

The programme has established defect task forces in each region, led by the Heads of

Network Operations, who are supported by Asset management and Health and Safety

teams that review the defects and responses identified on a monthly basis. The inclusion of

Asset Management teams in the programme also ensures that uniform defect resolution

approach are adopted across the regions.

Table 10: Task force structure

Through a focussed approach to network defects, the programme has successfully reduced

the outstanding volume of defects by 33% by the end of December 2012. The current

defects in the asset register are being regularly analysed to see redundancies and

duplicates while also resolving any incorrectly categorised defects that need attention.



Table 11: Defect Management – UKPN Performance

LPN has contributed significantly to the overall progress. This has resulted in 47% reduction

in outstanding defects for LPN.

Table 12: Defect Management – LPN Performance

Defect reporting tool

An online defect reporting tool has been developed to improve visibility of the defects and

aid planning for resolution of defects. The reporting tool is accessible by both UKPN staff

and its contractors. The report enables effective access and viewing of the defects as well as

development of progress graphs for efficient monitoring and tracking of key performance

indicators.

Defect inspectors handbook

A handbook on defects for inspectors is being developed to improve clarity on what

constitutes a defect. This will cover all defect categories, not just the categories detailed

throughout this document. The handbook will aid improved reporting and understanding of

each defect and is planned for completion by the end of 2013.

Cable pits

Inspection and risk management of cable pits is being enhanced as an Industry leading

initiative. UKPN is undertaking a complete evidence based evaluation strategy of cable pit

risk. An Innovation Funding Incentive project (IFI) has been launched to support the

research.



Key aspects of the strategy include:

1. Identification of the key aspects associated with the risks posed by cable pits

2. Identification of the mitigation actions that may be taken to reduce the risks posed

by cable pits

3. Design of a risk assessment methodology that can be applied in a desk-based

study and be applied in the field by the inspectors

4. Run the desk-based analysis to assess the likely risk posed by individual cable

pits and develop the associated Criticality Index

5. Design the cable pit survey methodology and forms to reflect the risk assessment

regime

The strategy has been developed and provides recommendations for a future inspection

regime. The following supporting documents have been produced during the development of

the strategy:

o Literature review

o Cover mitigations

o Arc suppression blankets

o Risk assessment methodology for cable pits

It is widely acknowledged that the presence of gas can exacerbate the effects of a disruptive

failure. Within the literature it can be observed that the most common strategy of mitigating

the effects of these disruptive faults is to form an assumptive stance; whereby a disruptive

fault is assumed to be inevitable. Consequently, relatively cheap mitigating safety devices,

such as tethered covers etc, can be deployed in order to mediate and mitigate the effects of

a fault and not to stop the fault occurring.

ESQC cable pit risk assessment

A risk assessment was developed to determine, through desk-based analysis, which assets

pose a risk and are more likely to require some form of mitigation.

The risk assessment will also be used to prioritise the ongoing inspection programme.

The equipment risk (likelihood factors) used within the desk-based approach are as follows:

o The number of joints in the pit



Likelihood

Parameter Rationale Number of Joints Equipment Risk

Number of joints

within the pit

Failure most often

occurs at joints

0

1

2

>=3

(where unknown

assume 1 joint)

Low

Low

Med

High

Table 13: Equipment risk ratings for cable pits

The location risk (consequence factors) used within the desk based approach principally

relate to:-

o The footfall of people

o The location of a pit within the enhanced zone where there is dual use of the

high and low voltage networks as this may mean more opportunity for cable

faults

Table 14: Location risk ratings for cable pits

As few of the pits have been inspected it was necessary to use available datasets to model

this risk assessment. This categorisation can also be applied in the field allowing inspectors

to individually calculate each cable pits risk category.

The overall risk score for a cable pit (Table 15) will be determined using a matrix based on

combining the Equipment Risk (likelihood) and the Location Risk (consequence).

Code Title DescrLocation

Risk

UA Enhanced Zone Within the enhanced zone High

UB Very High Pedestrian Area

Any medium or low risk area which is subject to consistent high pedestrian traffic

or gatherings e.g.

- Major rail, tube or bus stations

- Close to road junctions

High

UC RecreationalWithin or adjacent areas of people congregation e.g. play areas, sports and

activity areas or public attractionMedium

UD TransportWithin 10m of public access to rail, underground or DLR station, bus or tram stop

or busy car parkMedium

UE School Outside a school, in an area where children and parents are likely to gather Medium

UF Urban Footpaths or verges in a residential or built-up areas Low

UG Non-Residential Non-residential footpaths or verges Low

UH Secure Site Within a secure location Low

UI Rural Rural location Low

UJ Roads Surfaced roads Low

UK Private Private land Low



Development of this risk assessment methodology has included sensitivity testing of the

likelihood and consequence scores against the cable pits surveyed during the pilot study.

Each cable pit is assigned a risk designation of Very High, High, Medium and Low.

Table 15: Overall risk rating for cable pits

From a total number of 47,748 chamber pits in the LPN area, the assessment resulted in

2,038 pits being classed as Very High risk and 3,105 pits classed as High risk.

Strategy risk hierarchy

The strategy is based on a consideration of three key areas of public safety, equipment

faults and risk reduction, and utilises a hierarchy of risk elimination and risk reduction. Since

it is not considered reasonably practicable to either make every chamber fault proof or to

replace every cover, due to the high costs that would be incurred, the following risk hierarchy

is being implemented:

1. Eliminate tripping hazards, poor condition covers and unable to lift covers, by

replacement with a standard cover. This will also include removing all ladders

within pits, as all ladders are considered to be unsafe. Implementing a systematic

cable pit inspection and cover replacement regime will enable the condition of

existing covers to be assessed

2. Eliminate the gas build up potential within chamber pits, by filling pits with inert

material such as sand. This will be applied to pits:

a) with a Very High risk rating where practically feasible

b) typically within High and Medium risk pits with a small chamber volume (< 1m3)

This may include removal of the frame and cover, and subsequent reinstatement

if the existing cover is in poor condition. The interval between inspections for

these dormant pits will also be increased

Equipment

RiskLow Medium High

High Medium High Very High

Medium Medium Medium High

Low Low Medium Medium

Location Risk



3. Eliminate the risk of cover collapse by filling dormant pits with inert material such

as sand. This can be applied to pits that do not contain any cables or joints, and

may typically be a larger void chamber or in a high footfall area. This may include

removal of the frame and cover, and subsequent reinstatement, if the existing

cover is in poor condition. The interval between inspections for these dormant

pits will also be increased

4. Reduce the severity of an injury where an arcing disruptive fault would result in

the cover being ejected and potentially cause a fatality, on those Very High risk

pits, not already mitigated by infilling. The mitigation shall ensure that the

chamber is able to vent through a vented, hinged or spring-type cover. The cover

would have an appropriate vent area (grill openings) within the surface, or open

quickly to vent and then close back into its frame, and have an appropriate clear

opening.

5. Reduce the severity of an injury where an arcing disruptive fault would result in

the cover being ejected with the potential for falling into an open chamber, by

providing a fall arrest system. This can be applied to those pits located in a high

footfall area, and typically with a high fault risk. The mitigation is for the pit to be

fitted with a fall arrest system such as an open grid floor located just below the

cover

6. Reduce the risk of arcing disruptive fault by rectifying joint defects, by

implementing a systematic inspection regime. Mitigations will include replacing

LV mains joints or LV service joints, or filling modern joints with resin

7. Reduce the risk of structural failure by implementing a systematic inspection

regime to identify and rectify structural defects. Defects may occur within the

chamber shaft, walls or roof, and may consist of poor brickwork (cracking, loss of

mortar etc), poor concrete (cracking, spalling etc), metalwork (corrosion, bending

etc) or other material defects

Innovation

The current UKPN methodology for cover replacement is to use concrete infill covers.

However, where there is a very high risk of a fault, infilling or a vented cover will be required.

Innovative cable pit covers are being researched and designed to ensure that an arcing

disruptive fault can quickly vent and dissipate, thereby reducing the risk of structural damage

and flying debris. In particular there is also the need to ensure that the pit cover remains

attached. This will reduce the consequences of disruptive failures, thus limiting property

damage and potential injuries and risk to members of the public.



This mitigation will be deployed to those chamber pits that have an ESQC rating of very

high. The mitigation proposals for cover replacement assessed three covers as potentially

appropriate: Clark Drain bespoke fault protection covers (Figure 11) within pedestrian areas,

the St Gobain Opt-Emax cover (Figure 12) within trafficked areas and the Structural Science

Composites (SSC) S Panel (Figure 13):

o The Clark Drain fault protection cover is a fabricated steel infill cover. It can

be fabricated in a number of sizes. The cover vents as the pressure

underneath lifts the cover which is constrained by means of bolts on each of

the four corners. These bolts have springs which allow the soft closure of the

cover.

Figure 11: Clark Drain bespoke fault protection cover

o The Saint Gobain Opt-Emax cover is a hinged ductile iron cover, which has a

range of ‘off the shelf’ sizes ranging from 600 x 450mm clear opening to 1800

x 750mm clear opening sizes. The hinges are integral to the cover and lock

into the frame.

Figure 12: St Gobain Opt-Emax cover

o The SSC ‘S Panel’ cover is a vented composite fibreglass cover. It measures

605 x 1365 mm and has 750 12mm diameter vents over its surface (providing

a vent area of ~10%). It has been developed with Consolidated Edison and is



the only product considered that has undertaken load tests on the underside

and arc event simulation tests. The testing is based on their use within a

chamber exposed to igniting gas and supports the use of vents and a locking

restraint system to reduce the possibility of ejection of the cover. UKPN are

developing a smaller ‘standard size’ 800x800 cover that will be fitted to the

majority of cable pits where a cover requires changing either due to damage

or mitigation.

Figure 13: Structural Science Composites (SSC) ‘S’ Panel

It should be noted that the first two covers have not been designed or tested for any specific

disruptive forces applied on the underneath of the covers. Further investigative testing and

design would be necessary.

UKPN therefore favour the SSC ‘S Panel’ cover and have proposed to adopt this cover as

the mitigation recommendation to reduce the severity of an injury associated with a cover

being ejected.

UKPN are also researching the use of a fall arrest system for deep pits to ensure that if the

covers are dislodged no person accidently falls in to the pit. The mitigation will consist of an

open grid floor just below the cover and applied to pits with ESQC rating of high or very high,

and to those pits with a depth >=3m.

Other innovative mitigations such as the use of arc suppression blankets have been

considered and rejected on the grounds of effectiveness, practicality and cost.

UKPN are engaged with subject experts from America to ensure previous lessons learnt on

similar cable pit projects overseas are captured to maximise cost efficiency.

As part of the development of the strategy, 373 trial inspections were completed by the end

2012 in the London area. Information gathered from the inspections is currently being

analysed to aid development of the strategy which will include condition and defect



information, an ESQCR risk assessment, as well as possible risk mitigations where a high

risk or key risk is identified. The strategy is to ensure that public safety risks are minimised at

optimal costs. Details of the trial inspection findings are included in Appendix 8.

Although the strategy is initially focusing on London where the highest risks have been

identified, it will be implemented across all of UKPN’s operational networks.

The inspection frequency strategy is in the development stage and is likely to vary

depending on the ESQCR risk assessment to ensure the most cost effective solution is

applied. It is proposed to inspect every chamber pit once, over a period of 8 years. Once

complete, the differing inspection regimes/timescales for each chamber category will then

commence. For example, it is proposed that CAT 1 dormant pits will be inspected every 18

years, compared to CAT 2 pits within the enhanced zone which will be inspected every 6

years. The inspection regime are currently proposed is as follows:

1. Cable Pits Cat 1 – a dormant pit or one which is used exclusively for

telecommunications apparatus [dormant pit will include any pit that has been

backfilled]

o Major inspection every 18 years

o Maintenance as required

2. Cable Pits Cat 2 – a pit present along HV cable routes and containing HV cables,

joints and associated equipment within the primary distribution system or a

combination of primary and secondary distribution apparatus

o Major inspection every 8 years or for those pits within the enhanced zone

every 6 years


3. Cable Pits Cat 3 – any pit that has had an arcing fault reported via AIRline

o Major inspection every 1 year, for a period of 3 consecutive years without

further fault


4. Cat 4 – any pit with a Very High or High risk rating

o Major inspection every year




7.0 ED1 Expenditure requirements for ESQCR Compliance

7.1 Method

Process to forecast the investment plan

Investment plan for ESQCR safety compliance in LPN is divided into two sub categories:

o Signage on substations

o Cable pits inspection and maintenance

The other areas of expenditure in ESQCR compliance are covered in specific asset group

documents.

ESQCR planning is built based on historical trends to establish a ‘business as usual’ volume

of issues found every year and applies data quality correction to ensure more realistic

volumes are forecast.

Wherever there is a skewed annual volume, which may be due to a system up

gradation/migration issues, the volumes are discounted in the forecasting, so as to not skew

the volume due to either very high or very low volumes in any given year.

As described in earlier sections, the Defect Management programme, currently being

executed by UKPN is expected to bring down the volume of outstanding defects to a

business as usual level by 2015.

Methodology for volume forecasting:

Figure 14: ED1 forecasting process

7.2 Constructing the plan The investment strategy for ED1 has been set to comply with ESQCR in order to minimise

the risk to members of the public and employees. This strategy has been applied to signage

and cable pits, and any additional defects identified will also be resolved during the ED1

period. The function of the defect management programme currently being executed is to

address the outstanding defects by the end of DPCR5 where reasonably practicable but in

Historical

Defect

Volumes

Data skew

correction

Data quality

improvement

factor

Annual

Volumes



some cases, such as the expansion of the cable defect rectification programme, it is

anticipated that some will roll over to the first year of ED1.

Due to cable pits presenting an unacceptable risk in recent years to members of the public,

the cable pit strategy has used:

o proposed inspection regime

o an extrapolation of findings from trial inspections

o risk reduction mitigations applied on the basis of the ESQC chamber pit risk

rating

Table 16 shows the itemised cost estimates associated with the strategy risk hierarchy

described earlier. Items 1, 2, 6 and 7 are based on percentages ascertained from the pilot

inspections. Items 3, 4 and 5 are based on percentages ascertained from the risk

assessment. The inspection (and re-inspection of very high & high risk pits) together with

any associated mitigations will be completed during ED1.

Table 16: Itemised Cost Estimates

The total cost of the cable pit strategy is outlined in Table 16 and the programme of

inspection, maintenance and mitigation has already commenced. To deliver the complete

strategy during ED1 will require the funding outlined in Table 17.

7.3 Additional considerations If an activity is required in a cable pit as a result of planned work, that would be considerd at

the time of completion without the need for a revisit. Other considerations may be following

the defect identification and inspector intervention.

7.4 Asset volumes & expenditure The table summarises the ESQCR Safety related expenditure for the ED1 period.

Costing

Risk Hierarchy Item Description Unit PriceEstimated % of

CPs

Cable Pit Count

V High Risk

Cable Pit Count

High Risk

Cable Pit Count

TotalTotal Cost

1. Inspection All CPs £71.50 100% 47748 £3,413,982

1. UTL / damaged cover replacement Estimated % from survey results, applied to H/M/L risk pits - footpath B125 cover £872.00 6.9% 3259 £2,841,560

1. UTL / damaged cover replacement Estimated % from survey results, applied to H/M/L risk pits - carriageway D400 cover £2,060.00 1.7% 780 £1,606,141

1. Ladder removal Estimated % from survey results, applied to all CPs £10.00 9.5% 4536 £45,361

2. Pit infill Chamber vol <1m3 - H/M risk pits £251.00 48.3% 22078 £5,541,517

2. Pit reinstatement Cover removal and full reinstatement for pit infill - H/M risk pits £1,145.00 8.0% 1770 £2,026,822

2. Pit infill Chamber vol <1m3 - VH risk pits £251.00 0.37% 175 £44,000

2. Pit infill Chamber vol >1m3 and <3m3 - VH risk pits £460.00 1.47% 701 £322,550

2. Pit infill Chamber vol >3m3 and <8m3 - VH risk pits £837.00 1.21% 578 £484,194

2. Pit infill Chamber vol >8m3 and <15m3 - VH risk pits £1,381.00 0.62% 298 £411,550

2. Pit reinstatement Cover removal and full reinstatement for pit infill - VH risk pits £1,145.00 8.0% 163 £187,129

3. Dormant (larger) pit infill Estimated as no. of CPs with 0 or 1 joint in residential areas £837.00 1.1% 512 £428,580

3. Dormant (larger) Pit Reinstatement Cover removal and full reinstatement for large pit infill £1,145.00 0.2% 87 £99,830

4. Vented cover - SSC lid All CPs with Overall Risk Score of 'Very High' - footpath B125 S panel £1,145.00 0.48% 2038 228 £261,400

4. Vented cover - SSC lid All CPs with Overall Risk Score of 'Very High'- carriageway D400 S panel £2,696.00 0.12% 2038 57 £153,872

5. Fall restraint - plate protection CPs 3m-4m depth, estimated % from survey results, applied to VH/H risk pits £1,381.00 0.24% 47 68 115 £158,815

5. Fall restraint - plate protection CPs 4m-5m depth, estimated % from survey results, applied to VH/H risk pits £1,381.00 0.0% 0 0 0 £0

5. Fall restraint - plate protection CPs 5m+ depth, estimated % from survey results, applied to all CPs £1,381.00 0.04% 8 11 19 £26,239

6. Defect joint Joint resin fill £500.00 0.5% 239 £119,370

6. Defect joint imploded Replacement joints £2,500.00 3.2% 1528 £3,819,840

7. Defect structural Remedy structural defects identifed from pilot inspections £3,000.00 0.8% 382 £1,145,952

Total Cost Based on 47748 cable pits in LPN area £23,138,704



Assets NAMP Description ED1 Total Expenditure

ED1 Total Volume

ED1 Yearly Expenditure

ED1 Yearly

Volume

Signs 1.13.05 ESQC Provision of warning signs

£206,088 18,368 £25,761 2,296

Cable Pit 2.05.08 Cable pit maintain £10,037,446 25,627 £1,254,681 3,203

2.30.15 Cable pit inspection £7,791,397 49,262 £973,925 6,158

Grand Total £18,034,931

93,257

£2,254,367

11,657

Table 17: LPN ESQCR Expenditure As shown in Figures 19 and 20, LPN has increased expenditure during the DPCR5 period to

address the challenge posed by disruptive failure of cable pits (Table 5). This expenditure is

required to mitigate and minimise any risk to public safety. All cable pits will be inspected

over a period of 8 years and these inspections will provide vital information on condition and

required mitigations and this in turn will enhance public safety. UKPN is leading the industry

with respect to cable pit risk management and has work closely with the Health & Safety

Executive (HSE) in developing the strategy to this level of asset management.

Signage

As previously mentioned in section 3.4, warning signs require replacement if they are

vandalised, faded, or found non compliant with ESQCR and UKPN Policy. An average

annual volume of 2,296 sign replacements is forecast for ED1. This is out of a total

population of 72,000 signs. Since 2010, LPN have procured an average annual volume of

1,382 signs.

NAMP Description ED1 Total Expenditure

ED1 Total Volume

ED1 Yearly Expenditure

ED1 Yearly Volume

1.13.05 ESQC Provision of

warning signs £206,088 18,368 £25,761 2,296

Table 18: LPN – ED1 expenditure on signage



Table 19: LPN expenditure trend on signs

There is a lack of information contained within the asset register for spend on signage in the

early years of DPCR5. The volumes of signs are known and the cost of these have been

calculated for ED1 forecasting.

Table 20: LPN usage trend on signs

ED1 Expenditure on cable pits

The itemised cost estimates provided in Table 16 have been programmed across the ED1

period and beyond. This includes:

o the cost associated with the ongoing inspection regime taking into account the

ongoing repetitive inspections and differing time spans between inspections for

categories of cable pit

o the ongoing repetitive equipment defect maintenance associated with pit covers,

joints and structural condition

o the one off cost associated with risk reduction mitigations



The total expenditure of £17.8m is broken down as follows:

NAMP Description ED1 Total Expenditure

ED1 Total Volume

ED1 Ave Yearly

Expenditure

ED1 Ave Yearly

Volume

2.05.08 Cable pit maintain £10,037,446 25,627 £1,254,681 3,203

2.30.15 Cable pit inspection £7,791,397 49,262 £973,925 6,158

Table 21: LPN cable pit expenditure

Table 22: LPN cable pit OPEX expenditure trend

Table 22 commentary: OPEX expenditure consists of ongoing annual inspections, ongoing

replacement of unable to lift or damaged standard covers, and ongoing repair of structural

defects. As previously noted, it is proposed to inspect every chamber pit once, over a period

of 8 years, but noting all Very High and High risk pits will be inspected in 2013. Once

complete, the number of annual re-inspections reduces accordingly. On a similar basis, it is

assumed that the rate of cover replacement and structural defect repair will also reduce after

the initial 8 year period. All Very High risk pits will be inspected annually, however, once the

mitigations have been carried out it is suggested that the risk category of each pit will also

reduce accordingly.



Table 23: LPN cable pit CAPEX expenditure trend

Table 23 commentary: CAPEX expenditure consists of implementing the proposed mitigation

measures over an 8 year period. The proposed mitigations measures are: ladder removal,

pit infill and reinstatement, dormant (larger) pit infill and reinstatement, provision of vented

covers on very high risk pits (SSC lid), provision of fall arrest grates, and replacement of

defective imploded joints. All Very High cable pits will be mitigated following inspection in

2013, hence why there is a significant difference between 2013 and other ED1 years.

Table 24: LPN cable pit OPEX volume trend



Table 25: LPN cable pit CAPEX volume trend

7.5 Commentary

The proposed investment level in ED1 for the proposed annual inspection programme and

mitigation implementation is £17.8m.

The DPCR5 investment period, prior to 2013, was not influenced by an over-arching cable

pit strategy. Therefore, the proposed investment through the ED1 period and beyond

represents a significant increase in both CAPEX and OPEX.

The OPEX and CAPEX costs result from the development of a comprehensive inspection

regime and risk based mitigation proposals, and will enable compliance with ESQCR in

order to minimise risks to the public, UKPN staff and its contractors.

An initial inspection programme of 373 pits has already been completed, and a further 5,143

inspections started in May 2013, with the intention of inspecting all the ‘very high’ and ‘high’

risk pits within the first year. The remainder of the LPN cable pit inspections will continue in

the remaining period of DPCR5 and through the ED1 period. A preliminary programme has

been established which prioritises the inspection programme, in terms of those postcodes

that contain the highest number of ’very high’ risk pits.

The cable pit strategy has also been driven by recent disruptive failures, of which there were

12 in 2012, one resulting in severe injury to members of the public. The strategy has

considered the three key areas of public safety, equipment faults and risk reduction, and

utilised a hierarchy of risk elimination and risk reduction. It is not considered reasonably

practicable to either make every chamber fault proof or to replace every cover, due to the

high costs that would be incurred. Therefore the proposed CAPEX mitigation measures have

been developed for implementation over an 8 year period.

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