Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

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ENGINEERING DESIGN STANDARD

EDS 06-0001

EARTHING STANDARD

Network(s):

EPN, LPN, SPN

Summary:

This standard outlines the earthing design and construction requirements for the
distribution network at all voltage levels and the associated substations.

Author:

Stephen Tucker

Date:

27/09/2016

Approved By:

Paul Williams

Approved Date:

10/10/2016

This document forms part of the Company’s Integrated Business System and its requirements are mandatory throughout UK
Power Networks. Departure from these requirements may only be taken with the written approval of the Director of Asset
Management. If you have any queries about this document please contact the author or owner of the current issue.

Applicable To

UK Power Networks

External

All UK Power Networks

G81 Website

Asset Management

Contractors

Capital Programme

ICPs/IDNOs

Connections

Meter Operators

HSS&TT

Network Operations

UK Power Networks Services

Other

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

2 of 11

Revision Record

Version

4.0

Review Date

27/09/2021

Date

27/09/2016

Author

Stephen Tucker

Why has the document been updated: Periodic review and minor revision to ensure consistency
with other earthing standards

What has changed:

•

Statutory requirements added (Section 4).

•

Construction and testing requirements added (Section 6).

•

Reference to EDS 06-0019 added (Section 7).

•

Earthing inspection, assessment and maintenance added (Section 9).

• Responsibilities section added (Section 14)

Version

3.1

Review Date

27/10/2016

Date

22/08/2012

Author

Stephen Tucker

COLD and HOT site definitions corrected. Reviewed for publishing on G81 website

Version

3.0

Review Date

30/09/2016

Date

30/09/2011

Author

Stephen Tucker

Revised to reflect the reclassification of Earthing Manual into design and construction standards

Version

2.0

Review Date

31/03/2016

Date

31/03/2011

Author

Stephen Tucker

Reviewed and updated to reflect the new Earthing Design Manual and Earthing Construction Manual
structure

Version

1.0

Review Date

31/03/2013

Date

31/03/2008

Author

Stephen Tucker

Original

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

3 of 11

Contents

1

Introduction ................................................................................................................ 4

2

Scope .......................................................................................................................... 4

3

Glossary and Abbreviations ..................................................................................... 4

4

Statutory Requirements ............................................................................................ 4

5

Background ................................................................................................................ 5

6

Application .................................................................................................................. 5

6.1

New Substations ......................................................................................................... 5

6.2

Existing Substations .................................................................................................... 5

7

Earthing Design .......................................................................................................... 6

8

Earthing Construction ............................................................................................... 7

9

Earthing Assessment and Maintenance .................................................................. 7

10

HOT Sites .................................................................................................................... 7

11

Substation Earthing Database .................................................................................. 7

12

Records ....................................................................................................................... 7

13

Further Advice ............................................................................................................ 7

14

Responsibilities .......................................................................................................... 8

14.1

Asset Management ..................................................................................................... 8

14.2

Infrastructure Planning ................................................................................................ 8

14.3

Capital Programme ..................................................................................................... 8

14.4

Distribution Planning ................................................................................................... 8

14.5

Network Operations .................................................................................................... 9

14.6

Connections Design .................................................................................................... 9

14.7

Competition-in-Connections ........................................................................................ 9

14.8

Engineering Audit ........................................................................................................ 9

14.9

ICPs and IDNOs ........................................................................................................ 10

15

References ................................................................................................................ 11

15.1

UK Power Networks Standards ................................................................................. 11

15.2

National Standards .................................................................................................... 11

Tables

Table 7-1 – Earthing Design Standards ................................................................................... 6

Table 8-1 – Earthing Construction Standards .......................................................................... 7

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

4 of 11

1

Introduction

This standard outlines the earthing design and construction requirements for the UK Power
Networks’ distribution networks and the associated substations.

2

Scope

This standard applies to:

• New electrical installations, connections and substations at all voltage levels from 230V

to 132kV.

• Existing substations where there is a material alteration or a substantial increase in earth

fault current.

3

Glossary and Abbreviations

Term

Definition

APP

Asset Portfolio Plan

EPR

Earth potential rise

COLD Site

A substation where the EPR is less than 430V or 650V (high reliability
protection)

HOT Site

A substation where the EPR is greater than 430V or 650V (high
reliability protection)

ICP

Independent Connection Provider

IDNO

Independent Distribution Network Operator

NAMP

UK Power Networks Network Asset Management Plan

ROEP

Rise of earth potential

4

Statutory Requirements

Earthing design and construction shall be carried out with due regard to the statutory
regulations detailed below:

• Health & Safety at Work Act 1974.

• Construction (Design and Management) Regulations 2015.

• Electricity Safety, Quality and Continuity Regulations 2002.

• Electricity Act 1989.

The following documents form the basis for earthing design and construction:

• ENA TS 41-24.

• ENA EREC S34.

• ENA EREC S36.

• BS EN 50522.

• BS 7430.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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5

Background

When a fault occurs on an electricity transmission or distribution network, it is possible for a
large current to flow in the general mass of earth. This current can cause a considerable
rise in potential on earthed metalwork, which may be accessible to the public and staff,
particularly those who are carrying out fault switching. In addition, without adequate
safeguards it is possible for this excessive rise in potential to be transferred onto adjacent
power cables and communication cables creating potential danger to anyone who might be
in contact which may be some distance from the actual fault. It is therefore essential that the
earthing and bonding arrangements for equipment associated with public electricity supply is
properly designed, correctly installed, and regularly tested and maintained.

The function of earthing and bonding is to:

• Provide a low impedance path to enable earth fault current at any point on the network to

be returned to the transformer neutral, without thermal or mechanical damage to the
connected equipment and to enable protection equipment to operate correctly.

• Limit the voltage rise on all metalwork and the surface of the ground to which persons

have normal access, to a safe value under all reasonably perceived conditions for faults
at each voltage level associated with the substation. The earthing system should be
constructed so as to prevent the establishment of dangerous potential differences
between parts of the substation, which a person may be contacting simultaneously.

6

Application

6.1

New Substations

The following shall be carried out at all new substations:

• Design a suitable earthing system.

• Determine the earth potential rise at the substation and update the substation earthing

database accordingly (refer to EDS 06-0002).

• Construct and test the earthing system.

• Carry out a post-construction earth resistance measurement and verify the design

values.

6.2

Existing Substations

The following shall be carried out prior to all major asset refurbishment, replacement or
extension works at a grid or primary substations:

• Carry out an earthing survey and assessment to confirm the suitability and integrity of

the existing earthing system

• Determine the earth potential rise at the substation and update the substation earthing

database accordingly (refer to EDS 06-0002).

• Design a suitable earthing system.

• Rectify any deficiencies highlighted by the survey.

• Construct and test the earthing system in accordance with this standard.

• Carry out a post-construction earth resistance measurement and verify the design

values.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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Note: These requirements may be excluded where robust records can demonstrate a survey
and assessment was completed in the last five years, the existing earthing system is
appropriate, the substation earthing database is up-to-date and the remaining service life will
match that of the new plant and equipment.

A provision shall be included in a project to cover the costs associated with the design of the
earthing system including the survey, assessment and any measurements. However any
remedial works associated with an existing earthing system shall be covered by the
appropriate maintenance APP line.

7

Earthing Design

The earthing design standards and their application are based on ENA TS 41-24 and
ENA EREC S34 but include the requirements of other standards where this is considered
appropriate and experience gained from previous earthing assessments and measurements.
Also, to ensure a consistent approach at sites shared with National Grid, the appropriate
practices have been included from NGTS 3.1.2. The criteria for designing earthing systems
are outlined in EDS 06-0012.

When designing earthing systems it is important to recognise that they perform differently at
high frequencies than at the lower frequency used for power distribution (50Hz). The
standards are mainly concerned with power frequency performance but some specific
designs have been included, where appropriate, to cater for high frequency aspects.

Earthing design shall be carried out in accordance with the standards detailed in Table 7-1.

Note: For any area of earthing not covered by the UK Power Networks’ earthing standards
refer to the guidelines detailed in ENA TS 41-24.

Table 7-1 – Earthing Design Standards

Description

New
Earthing
Design
Standard

Old
Earthing
Design
Manual

Old
Earthing
Manual

Earthing Design Criteria

EDS 06-0012 Section 2

Section 2

Grid and Primary Substation Design

EDS 06-0013 Section 3

Section 3

Secondary Distribution Substation Earthing Design

EDS 06-0014 Section 4

Section 5

Pole-Mounted Equipment Earthing Design

EDS 06-0015 Section 5

Section 6

LV Network Earthing Design

EDS 06-0016 Section 6

Section 7

Customer EHV and HV Connections (including
Generation) Earthing Design and Construction
Guidelines

EDS 06-0019 n/a

n/a

Customer LV Installation Earthing Design

EDS 06-0017 Section 7

Section 7

NetMap

1

Earthing Information System

EDS 06-0018 Section 8

n/a

1

UK Power Networks GIS system.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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8

Earthing Construction

Earthing construction, testing and measurements shall be carried out in accordance with the
standards detailed in Table 8-1.

Table 8-1 – Earthing Construction Standards

Standard

New Earthing
Construction
Standard

Old Earthing
Construction
Manual

Old
Earthing
Manual

Grid and Primary Substation Earthing Construction

ECS 06-0022

Section 2

Section 4

Secondary Distribution Network Earthing
Construction

ECS 06-0023

Section 3

Section 5

Earthing Testing and Measurements

ECS 06-0024

Section 4

Section 8

9

Earthing Assessment and Maintenance

Earthing inspection, assessment and maintenance shall be carried in accordance with
EMS 10-0601.

10

HOT Sites

The earthing design and construction standards cover the requirements for HOT sites and
include the obligations to third parties.

The HOT site register (EDS 06-0003) provides details of how third parties can obtain HOT
site information for substations owned by UK Power Networks.

UK Power Networks internal process for managing and recording HOT sites is detailed in
EDS 06-0002.

11

Substation Earthing Database

The substation earthing database contains the earthing related data for all grid and primary
substations together with the substation classification. Refer to EDS 06-0002 for further
information.

12

Records

All earthing drawings and reports (survey, design, measurement, post-construction etc.)
shall be sent to

[e-mail]

for inclusion in the earthing

database and document management system.

13

Further Advice

Specialist advice on all aspects of earthing is available from the author of this document.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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14

Responsibilities

14.1

Asset Management

Asset Management is responsible for providing advice on all aspects of earthing.

14.2

Infrastructure Planning

Infrastructure Planning Engineer is responsible for ensuring that all infrastructure projects
include an allocation for earthing design, construction and testing.

14.3

Capital Programme

The Design Engineer is responsible for:

• Ensuring that all new substations or changes to existing substations have an earthing

design in accordance the relevant earthing standards.

• Where required, providing the relevant data to customers to allow them to carry out the

earthing design.

• Ensuring any customer earthing design is in accordance with the relevant earthing

standards.

• Ensuring that all substations are safe and COLD wherever practical and any remedial

actions are incorporated into the substation design.

• Ensuring that all earthing related data is sent

to

[e-mail]

for inclusion in the substation earthing

database.

The Project Manager is responsible for:

• Ensuring that all secondary substations are constructed and tested in accordance with

the relevant earthing construction standards.

• Ensuring that all earthing related data is sent

to

[e-mail]

for inclusion in the substation earthing

database.

14.4

Distribution Planning

The Distribution Planning Engineer is responsible for:

• Ensuring that all new secondary substations or changes to existing secondary

substations have an earthing design in accordance the relevant earthing standards.

• Advising telecommunications operators when designing a new substation in the vicinity

of a telecommunications exchange.

• Sending the earthing design and construction forms to Network Operations.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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14.5

Network Operations

Network Operations are responsible for:

• Ensuring that all secondary substations are constructed and tested in accordance with

the relevant earthing construction standards.

• Ensuring that all earthing design and construction data is sent

to

[e-mail]

for inclusion in the substation earthing

database.

14.6

Connections Design

The Connections Designer or Project Manager is responsible for:

• Ensuring that all new substations or changes to existing substations have an earthing

design in accordance the relevant earthing standards.

• Where required, providing the relevant data to customers to allow them to carry out the

earthing design.

• Ensuring any customer earthing design is in accordance with the relevant earthing

standards.

• Advising telecommunications operators when designing a new substation in the vicinity

of a telecommunications exchange.

• Sending the earthing design and construction forms to Network Operations.

14.7

Competition-in-Connections

The Competition-in-Connections team are responsible for:

• Providing the relevant data to ICPs to allow them to carry out the earthing design.

• Assessing submitted ICP earthing designs and ensuing compliance with the relevant

earthing standards.

• Ensuring that all earthing related data is sent

to

[e-mail]

for inclusion in the substation earthing

database.

14.8

Engineering Audit

The Audit Engineer is responsible for:

• Ensuring that all substations are constructed and tested in accordance with the relevant

earthing construction standards.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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14.9

ICPs and IDNOs

Independent Connection Providers (ICP) and Independent Distribution Network Operators
(IDNO) are responsible for:

• Ensuring that all UK Power Networks’ substations are designed, constructed and tested

in accordance with the relevant earthing standards.

• Providing sufficient data to allow UK Power Networks to review and assess substation

earthing designs.

• Advising telecommunications operators when a new substation is situated in the vicinity

of a telecommunications exchange.

• Ensuring that all earthing related data is sent to UK Power Networks’ Competition-in-

Connections Delivery Project Manager for inclusion in the substation earthing database.

Earthing Standard

Document Number: EDS 06-0001

Version: 4.0

Date: 27/09/2016

© UK Power Networks 2016 All rights reserved

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15

References

15.1

UK Power Networks Standards

EDS 06-0002

HOT Site Requirements (internal document only)

EDS 06-0003

HOT Site Register

EDS 06-0004

Earth Fault Loop Impedance Requirements (internal document only)

EAS 06-0011

Earthing Materials

EDS 06-0012

Earthing Design Criteria

EDS 06-0013

Grid and Primary Substation Earthing Design

EDS 06-0014

Secondary Distribution Substation Earthing Design

EDS 06-0015

Pole-Mounted Equipment Earthing Design

EDS 06-0016

LV Network Earthing Design

EDS 06-0017

Customer Installation Earthing Design

EDS 06-0018

NetMap Earthing Information System (internal document only)

EDS 06-0019

Customer EHV and HV Connections (including Generation) Earthing Design
and Construction Guidelines

ECS 06-0022

Grid and Primary Substation Earthing Construction

ECS 06-0023

Secondary Distribution Network Earthing Construction

ECS 06-0024

Earthing Testing and Measurements

EMS 10-0601

Earthing Inspection, Assessment and Maintenance (internal document only)

15.2

National Standards

ENA TS 41-24

2

Guidelines for the Design, Installation, Testing and Maintenance of Main
Earthing Systems in Substations

ENA EREC S34

2

A Guide for Assessing the Rise of Earth Potential at Substation Sites

ENA EREC S36

2

Procedure to Identify and Record HOT Substations

NG TS 3.1.2

Earthing

BS EN 50522

Earthing of Power Installations Exceeding 1kV AC

BS 7430

Code of Practice for Protective Earthing of Electrical Installations

2

Available from www.energynetworks.org.