IMP/001/013 Document TypeDocument reference Version:- …IMP/001/013 1.0 Code of Practice for Guidance on the Selection of Underground Cable Ratings 2 Scope The ratings stated in this

Document reference Document reference IMP/001/013 Document Type: Code of Practice Version:- 1.1 Date of Issue:- October 2015 Page 1 of 34

CAUTION! - This document may be out of date if printed

IMP/001/013 Code of Practice for Guidance on the Selection of Underground Cable Ratings

1 Purpose

The purpose of this document is to state Northern Powergrid’s policy for the selection of ratings to be applied to underground cables at all voltage levels. The document applies to the distribution systems of both Northern Powergrid Northeast and Northern Powergrid Yorkshire, the licensed distributors of Northern Powergrid.

This Code of Practice also helps to ensure the company achieves its requirements with respect to the Electricity Act 1989 (as amended by the Utilities Act 2000 and the Energy Act 2004), The Electricity Safety, Quality and Continuity (ESQC) Regulations 2002 (as Amended)

1, the Health and Safety at Work Act 1974, the Electricity Distribution

Licences, The Distribution Code and The Grid Code.

This document supersedes the following documents, all copies of which should be removed from circulation.

Ref Version Title

IMP/001/013 1.0 Code of Practice for Guidance on the Selection of Underground Cable Ratings

2 Scope

The ratings stated in this document apply to:

existing underground distribution cables at all voltage levels.

new underground distribution cables at all voltages installed as part of distribution system developments including new connections, system reinforcement and asset replacement.

1 This includes The ESQC (Amendment) Regulations 2006 (No. 1521, 1st October 2006) and The ESQC (Amendment) Regulations 2009 (No. 639, 6th April 2009).



2.1 Table of contents

1 Purpose .................................................................................................................................................................. 1

2 Scope ...................................................................................................................................................................... 1

2.1 Table of contents .......................................................................................................................................................... 2

3 Code of practice ..................................................................................................................................................... 4

3.1 Assessment of relevant drivers ..................................................................................................................................... 4 3.1.1 Requirements of the Electricity Act 1989 (as amended) .............................................................................................. 4 3.1.2 The Health and Safety at Work Act 1974 ...................................................................................................................... 4 3.1.3 Requirements of The Electricity Safety, Quality and Continuity (ESQC) Regulations ................................................... 4

3.2 Key policy requirements ............................................................................................................................................... 5

3.3 Underground cable ratings ........................................................................................................................................... 5 3.3.1 General ......................................................................................................................................................................... 5 3.3.2 Existing cable ratings .................................................................................................................................................... 6 3.3.2.1 Existing low-voltage cable ratings ................................................................................................................................. 6 3.3.2.2 Existing high-voltage cable ratings................................................................................................................................ 7 3.3.2.3 Existing 33kV and 66kV cable ratings............................................................................................................................ 7 3.3.2.4 Existing 132kV cable ratings ......................................................................................................................................... 8 3.3.3 New cable installations ................................................................................................................................................. 8 3.3.3.1 General ......................................................................................................................................................................... 8 3.3.3.2 Rating selection ............................................................................................................................................................ 8 3.3.3.3 New low-voltage cable ratings ...................................................................................................................................... 9 3.3.3.4 New high-voltage cable ratings .................................................................................................................................... 9 3.3.3.5 New 33 and 66kV cable ratings................................................................................................................................... 10 3.3.3.6 New 132kV cable ratings ............................................................................................................................................ 10 3.3.4 De-rating factors ......................................................................................................................................................... 10 3.3.4.1 Depth of laying ............................................................................................................................................................ 10 3.3.4.2 Thermal resistivity of soil ............................................................................................................................................ 10 3.3.4.3 Ambient temperature ................................................................................................................................................. 11 3.3.4.4 Proximity ..................................................................................................................................................................... 11 3.3.5 Ducts ........................................................................................................................................................................... 11

4 References ........................................................................................................................................................... 12

4.1 External documentation ............................................................................................................................................. 12

4.2 Internal documentation .............................................................................................................................................. 14

4.3 Amendments from previous version .......................................................................................................................... 15

5 Definitions ............................................................................................................................................................ 16

6 Authority for Issue ....................................................................................................... Error! Bookmark not defined.

6.1 CDS assurance ................................................................................................................. Error! Bookmark not defined.



6.2 Author ............................................................................................................................. Error! Bookmark not defined.

6.3 Technical assurance ........................................................................................................ Error! Bookmark not defined.

6.4 Authorisation .................................................................................................................. Error! Bookmark not defined.

Appendix 1a – Existing LV underground cable ratings .......................................................................................................... 17

Appendix 1b – Existing HV underground cable ratings ......................................................................................................... 19

Appendix 1c – Existing 33kV and 66kV underground cable ratings ...................................................................................... 20

Appendix 1d – Existing 132kV underground cable ratings .................................................................................................... 24

Appendix 2a – New LV cable ratings .................................................................................................................................... 25

Appendix 2b – New HV cable ratings ................................................................................................................................... 26

Appendix 2c – New 33kV cable ratings ................................................................................................................................ 27

Appendix 3a – De-rating factors for depth ........................................................................................................................... 28

Appendix 3b – De-rating factors for thermal resistivity of soil ............................................................................................. 29

Appendix 3c – De-rating factors for ambient temperature .................................................................................................. 30

Appendix 3d – De-rating factors for proximity, single cores laid direct ................................................................................ 31

Appendix 3e – De-rating factors for proximity, single cores laid in ducts ............................................................................. 32

Appendix 3f – De-rating factors for proximity, multi-core cables laid direct ........................................................................ 33

Appendix 3g – De-rating factors for proximity, multi-core cables laid in ducts .................................................................... 34



3 Code of practice

3.1 Assessment of relevant drivers

The key internal business drivers relating to the selection and application of underground cable ratings are:

Employee commitment - achieved by providing our employees with the information necessary to develop a distribution system that is fit for purpose;

Financial strength - achieved by developing a distribution that has a minimum overall lifetime cost;

Customer service - achieved by providing information on equipment ratings to third parties who are interested in a connection the Northern Powergrid’s distribution system;

Regulatory integrity - achieved by designing a robust system that meets mandatory and recommended standards;

Environmental respect - achieved through due consideration being given to the environmental impact of new developments including the impact on system losses and carbon footprint; and

Operational excellence - achieved through improving the quality, availability and reliability of supply.

The external business drivers relating to the selection and application of underground cable ratings are detailed in the following sections.

3.1.1 Requirements of the Electricity Act 1989 (as amended)2

Section 9 (1) of the Electricity Act 1989 (as amended) places an obligation on Distribution Network Operators (DNOs) to develop and maintain an efficient, co-ordinated and economical system of electricity distribution and to facilitate competition in the supply and generation of electricity.

Discharge of this obligation is supported by this document in providing guidance on the application of appropriate cable ratings.

3.1.2 The Health and Safety at Work Act 1974

Section 2(1) of The Health and Safety at work Act 1974, states that ‘It shall be the duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all his employees.’ Section 3(1) also states that ‘It shall be the duty of every employer to conduct his undertaking in such a way as to ensure, so far as is reasonably practicable, that persons not in his employment who may be affected thereby are not thereby exposed to risks to their health or safety.’

This is addressed in this Code of Practice by:

Stating the continuous, cyclic and, where applicable, emergency rating appropriate to underground cables forming the distribution system.

3.1.3 Requirements of The Electricity Safety, Quality and Continuity (ESQC) Regulations

The ESQC Regulations 2002 (No.2665, 31st January 2003) and its amendments3 impose a number of obligations on

the business, mainly relating to safety and quality of supply. All the requirements of the ESQC Regulations that are applicable to the design and development of the distribution system shall be complied with.

2 The Utilities Act 2000 and The Energy Act 2004 and The Energy Act 2004 (Amendment) Regulations 2012 (No. 2723, 2012)



Reg. No Text Application to this Code of Practice

3(1)(a) …distributors…shall ensure that their equipment is sufficient for the purposes for and the circumstances in which it is used.

This Code of Practice will contribute to compliance with the ESQC Regulations by requiring that analysis is carried out to ensure that the continuous and cyclic duties to which equipment is exposed is within its capability.

23 A distributor shall ensure that his network shall be- (a) so arranged… as to restrict, so far as is reasonably practicable, the number of consumers affected by any fault in his network.

Guidance is given on the application of appropriate underground cable ratings such that an appropriate level of demand can be secured during outage conditions.

3.2 Key policy requirements

The general objective in operating and developing the distribution system is to obtain a simple and robust system having minimum overall cost, taking into account the initial capital investment, system losses and the maintainability and operability over the life of the asset.

This Code of Practice is written to help ensure that the distribution system is operated and developed in such a way as to:

prevent danger to members of the public and Northern Powergrid staff and our sub-contractors;

discharge the obligation under section 9 of the Act, and specifically to have due regard to future requirements and network performance;

ensure the underground cable network has an appropriate capacity to supply our Customers under normal and outage conditions; and

satisfy all other relevant obligations.

3.3 Underground cable ratings

This Code of Practice is split into three main parts; section 3.3.2 covering ratings applicable to existing cables, section 3.3.3 covering ratings applicable to new installations and section 3.3.4 covering de-rating factors for cables installed in conditions other than those normally applied for either existing or new cable installations.

3.3.1 General

The ratings quoted in this document are typical generic values for different cable types installed under the conditions quoted. It is worth noting that a significant number of the existing cables used on the distribution system were designed, manufactured and installed many years ago; the specifications, material uses and design tolerances have changed during this period and it can be difficult to state a definitive rating for every cable deployed in the distribution system, hence the use of generic ratings. If the rating of a particular cable is critical then a more accurate assessment of on-site conditions combined with manufacturer specific ratings may be required. This will involve detailed engineering calculations that may require the use of analytical software

3 This includes The ESQC (Amendment) Regulations 2006 (No. 1521, 1st October 2006) and The ESQC (Amendment) Regulations 2009 (No. 639, 6th April 2009).



(Northern Powergrid presently approve the use of the EA Technology software called CRATER for this purpose as it has been developed in conjunction with DNOs via our innovation programme) . The engineering analysis will allow on-site conditions

4 and specific cable characteristics to be modelled in order to produce a bespoke cable rating. It

is worth noting that the choice of a cable backfill with a lower thermal resistivity can release additional capacity in new installations

5. Appendix 3b details typical gains that can be possible with different backfill thermal resistivity.

When selecting the appropriate maximum conductor operating temperature of the cable, care should be taken to ensure that the operating temperature of the new cable matches that of any existing cable that is to be connected to it. New cables may have to be de-rated to a lower operating temperature to ensure maximum operating temperatures are not exceeded on existing cables and in such cases assessment of the reduced rating is required to ensure the capacity of the new cable is sufficient for the circumstances in which it is to be used

6.

The de-rating factors in section 3.3.4 shall be used for cables installed in conditions other than those stated.

3.3.2 Existing cable ratings

The ratings stated in Appendix 1 are derived from a variety of sources including:

Ratings for imperial three and four core cables manufactured to BS 480 are given in BEBS-C2 (copper conductors), BEBS-C6 (aluminium conductors) and ERA report F/T 183.

Ratings for imperial split-concentric cables are given in BEBS specification C7 schedule D.

Ratings for cables manufactured to BS 6480 are given in ERA report 69-30 Part 1.

Ratings for cables manufactured to BS 6346 are given in ERA report 69-30 Part 3.

Ratings for concentric service cables are given in EATS 09-7 Table 1.

Ratings for split-concentric service cables manufactured to BS 4553 are given in the schedules of Engineering Recommendation C67.

Ratings for three phase polymeric insulated CNE service and distribution cables shall be the same as the equivalent size 4 core armoured LV cable manufactured to BS 6480.

Emergency cable ratings are provided for operational purposes only.

3.3.2.1 Existing low-voltage cable ratings

Ratings for existing low-voltage (LV) cables can be found in Appendix 1a. All the current ratings provided relate to LV underground cables laid direct in the ground. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices.

The ratings for LV cables are based on the following installation conditions:

4 E.g. the presence of other cable, cables installed in ducts or at non-standard depths.

5 The use of special stabilised backfill is only typically viable for EHV and 132kV cables where the costs of installing a larger

size cable may be prohibitive and where the installation conditions are such that the backfill is likely to be undisturbed during the life of the cable installation.

6 This is particularly relevant where an XLPE cable with an operating temperature of 90°C is connected to a paper insulated

cable with an operating temperature of 65°C.



Ambient temperature Air 25°C

Soil 15°C

Thermal resistivity of soil 1.2oC.m/W

Depth of laying (to centre of cable) 0.5m

Maximum conductor temperature LV cable (belted) 80°C

LV cable, PILC, XLPE 80°C

LV cable, consac 90°C

Concentric and Split-concentric service cable 70°C

As these cables are typically laid as a single circuit they are assumed to be thermally independent of other cables.

3.3.2.2 Existing high-voltage cable ratings

Ratings for existing high-voltage (HV) cables can be found in Appendix 1b. All current ratings provided apply to underground cables laid direct in the ground. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices. If further guidance is required on cable ratings, reference should be made to Asset Management Underground Cables Engineer.

The ratings for high-voltage cables are based on the following installation conditions:


Soil 15°C


Depth of laying (to centre of cable or trefoil group) 0.8m

Maximum conductor temperature HV cable, PILC, belted, solid 65°C

Cross-linked polyethylene (XLPE) 90°C

As these cables are typically laid as a single circuit they are assumed to be thermally independent of other cables.

3.3.2.3 Existing 33kV and 66kV cable ratings

Ratings for existing 33kV and 66kV cables can be found in Appendix 1c. All current ratings provided apply to underground cables laid direct in the ground. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices. If further guidance is required on cable ratings, reference should be made to Asset Management Underground Cables Engineer.

The ratings for 33kV and 66kV cables are based on the following conditions:




Soil 15°C


Depth of laying (to centre of cable or trefoil group) 0.8m

Maximum conductor temperature XLPE cables 90°C

PPL 90°C

Pressure cables, PILC 85°C

Paper cables 65°C

Cables laid as single circuit and are thermally independent of other cables.

3.3.2.4 Existing 132kV cable ratings

Ratings for existing 132kV cables can be found in Appendix 1d. All current ratings provided apply to underground cables laid direct in the ground. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices. If further guidance is required on cable ratings, reference should be made to Asset Management Underground Cables Engineer.

The ratings for 132kV cables are based on the following conditions:


Soil 15°C


Depth of laying (to centre of cable or trefoil group)

0.8m

Maximum conductor temperature XLPE cables 90°C

Pressure cables 85°C

Paper cables 65°C


3.3.3 New cable installations

3.3.3.1 General

All cables shall be installed in accordance with the requirements of the Policy for the Installation of Distribution Power Cables, NSP/002.

3.3.3.2 Rating selection

Three ratings have been provided in appendix 2 for continuous, cyclic and emergency conditions, both for laid direct and ducted installations. As a general rule, the continuous as laid rating should be used when assessing the suitability of a particular cable and this should accommodate the expected initial and future loading on the cable under all expected running arrangements. The cyclic rating of a cable may be used in line with guidance provided



in the following Codes of Practice which also provide further information on the appropriate choice of cable and additional considerations:

Economic Development of Low Voltage Networks, IMP/001/911

Economic Development of the HV System, IMP/001/912

Economic Development of the EHV System, IMP/001/913

Economic Development of the 132kV System, IMP/001/914

Emergency cable ratings are provided for operational purposes only.

An assessment of the change in electrical losses arising from the different cable options being considered shall also be made in accordance with the Code of Practice for the Assessment of Asset Specific Losses, IMP/001/103.

3.3.3.3 New low-voltage cable ratings

Laid direct and ducted ratings for new LV cables can be found in Appendix 2a. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices.

The ratings for LV cables are based on the following conditions:


Soil 15°C


Depth of laying (to centre of cable) 0.5m for LV

Maximum conductor temperature Concentric and Split-concentric service cable 70°C

Waveform 80°C

Cross-linked polyethylene (XLPE) 90°C


3.3.3.4 New high-voltage cable ratings

Laid direct and ducted ratings for new HV cables can be found in Appendix 2b. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices. Ratings for 6kV cables have not been provided as this is a non-preferred voltage for which cable ratings shall be provided upon request. Any cable connections made to existing 6kV infrastructure shall be capable of being operated at 11kV.

The ratings for HV cables are based on the following conditions:


Soil 15°C




Depth of laying (to centre of cable) 0.8m for 11kV and 20kV

Maximum conductor temperature Cross-linked polyethylene (XLPE) 90°C


3.3.3.5 New 33 and 66kV cable ratings

Laid direct and ducted ratings for new 33kV cables can be found in Appendix 2c. Ratings for cables installed under other conditions should be obtained by applying the de rating factors provided in section 3.3.4 and the associated appendices.

The ratings for 33kV cables are based on the following conditions:


Soil 15°C


Depth of laying (to centre of cable) 0.8m

Maximum conductor temperature Cross-linked polyethylene (XLPE) 90°C


Ratings for new 66kV cables shall be determined on a bespoke basis using manufacturer’s data for the specific cable to be purchased with any adjustments for rating made for on-site conditions. Cable rating software (e.g. CRATER) should be used in order to determine a bespoke rating for new 66kV circuits.

3.3.3.6 New 132kV cable ratings

Ratings for new 132kV cables shall be determined on a bespoke basis using manufacturer’s data for the specific cable to be purchased with any adjustments for rating made for on-site conditions. Cable rating software (e.g. CRATER) should be used in order to determine a bespoke rating for new 132kV circuits.

3.3.4 De-rating factors

3.3.4.1 Depth of laying

The de-rating factors stated in appendix 3a shall be applied to all cables up to and including 33kV whose depth differs from the aforementioned standard installation depth. Refer to the Policy for the Installation of Distribution Power Cables, NSP/002 for information on appropriate depths of cables in different ground.

3.3.4.2 Thermal resistivity of soil

Work undertaken as part of the Customer Led Network Revolution (CLNR) project7 suggests that the standard

installation values of soil resistivity used to determine cable ratings in Engineering Recommendation P17, parts 1-3

7 A Review of Engineering Recommendations P15, P17 and P27 (Transformers, Cables and Overhead Lines), document

number CLNR-L263, section 4.1.1, Review of Standard Environmental Conditions.



are considerably lower at 0.9oC.m/W than measured values taken at Northern Powergrid substation sites. From

the sites measured, soil resistivity values varied between 1.5oC.m/W and 2.0

oC.m/W. The historical standard for

soil resistivity in Northern Powergrid is 1.2oC.m/W and this value shall be used until further consideration and

analysis is given to the outputs of the CLNR project.

The de-rating factors stated in appendix 3b shall be applied to all cables up to and including 33kV laid in soil where the average thermal resistivity is at values other than 1.2

oC.m/W.

3.3.4.3 Ambient temperature

The de-rating factors stated in appendix 3c shall be applied to cables up to and including 33kV laid in soil where the ambient ground temperature is at temperatures other than 15

oC.

3.3.4.4 Proximity

All de-rating factors quoted are based on the centre to centre spacing of each cable in the case of multi-core cables or the centre to centre spacing of each group of cables in the case of single core cables laid in either flat or trefoil formation. As per section 2.1(b) of Engineering Recommendation P17, Current Rating Guide for Distribution Power Cables, for cables laid in close proximity to other loaded circuits where runs are short (say less than 15m) and the congestion is not excessive, the effects of proximity de-rating can be ignored.

Single core cables laid direct

The de-rating factors in appendix 3d shall be applied to single core cables up to and including 33kV that are in close proximity to other underground cables and laid direct.

Single core cables laid in ducts

The de-rating factors in appendix 3e shall be applied to single core cables up to and including 33kV that are in close proximity to other underground cables and laid in ducts.

Multi-core cables laid direct

The de-rating factors in appendix 3f shall be applied to multi-core cables up to and including 33kV that are in close proximity to other underground cables and laid direct.

Multi-core cables laid in ducts

The de-rating factors in appendix 3g shall be applied to multi-core cables up to and including 33kV that are in close proximity to other underground cables and laid in ducts.

3.3.5 Ducts

As per section 2.1(a) of Engineering Recommendation P17, Current Rating Guide for Distribution Power Cables, for cables laid direct that contain a continuous ducted section of less than 15m in length, the effects of duct de-rating can be ignored. Cables laid in ducts that are filled with an appropriate bentonite filling that is appropriately sealed into the duct shall be rated as if it was laid direct.



4 References

4.1 External documentation

Reference Title Version and date

Engineering Recommendation P17, Part 1

Current Rating Guide for Distribution Cables 1976


Solid Type Cables for 33kV 1976


Ratings for 11kV and 33kV Cables having extruded insulation Issue 1, 2004

Engineering Recommendation C55/4

Insulated Sheath Power System Cables 1989

HSAWA The Health and Safety at Work Act 1974

SI 2002 No. 2665 The Electricity Safety, Quality and Continuity Regulations 31 January 2003

SI 2006 No. 1521 The ESQC (Amendment) Regulations 2006 1 October 2006

SI 2009 No. 639 The ESQC (Amendment) Regulations 2009 6 April 2009

The Act The Electricity Act 1989 (as amended by The Utilities Act 2000 and The Energy Act 2004 and The Energy Act 2004 (Amendment) Regulations 2012 (No. 2723, 2012)

2012

The Distribution Code

The Distribution Code covers all material technical aspects relating to connections to the operation and use of the Distribution Network Operators (DNO’s).

Issue 24 July 2014

The Grid Code The Grid Code sets out the operating procedures and principles governing the relationship between NGET and all Users of the National Electricity Transmission System be they Generators, DC Converter owners, Suppliers or Non-Embedded Customers.

Issue 5 Revision 13 January 2015

The Electricity Distribution License

Standard conditions of the Electricity Distribution Licence. April 2015

BS 480 Impregnated paper insulated cables for electricity supply for working voltages up to and including 33kV (imperial units)

BEBS-C2 Specification for impregnated paper insulated solid type lead or lead alloy sheath power cables for voltages up to and including 22kV (incorporating amendments 1 to 6 inclusive)

BEBS-C6 Specification for impregnated paper insulated solid type lead or lead alloy sheath power cables having aluminium conductors for voltages up to and including 22kV (incorporating amendments 1 to 3 inclusive)

ERA Report F/T183 Current ratings for paper insulated cables to BS 480 (1954) and varnished – cambric – insulated cables to BS 608 (1955)

BEBS-C7 Specification for polyvinylchloride insulated power cables for voltages up to and including 3,300 volts (incorporating amendments 1 to 9 inclusive)

BS 6480 Impregnated paper insulated cables for electricity supply – lead or




lead alloy sheathed cables for working voltage up to and including 33kV (metric units)

ERA Report 69-30 (Part 1)

Sustained ratings for paper insulated lead covered cables to BS 6480 1969

EATS 09-7 PVC insulated concentric service cables with stranded copper or solid aluminium phase conductors and copper concentric conductors

BS 4553 PVC insulated split concentric cables with copper conductors

Engineering Recommendation C67

Specification for impregnated paper insulated solid type cables for voltages up to and including 33,000 volts and PVC insulated cables for voltages up to and including 3,300 volts

ERA Report 69-30 (Part 3)

Sustained ratings for PVC insulated cables to BS 6346 1969



4.2 Internal documentation


NPS/002/019 Technical Specification for LV Distribution and Service Cables 5.1 June 2015

NPS/002/020 Technical Specification for 11 & 20kV Power Cables 4.1 June 2015

NPS/002/021 Technical Specification for 33kV Power Cables 4.0 June 2015



NSP/002 Policy for the Installation of Distribution Power Cables 2.0 Sept 2015

IMP/001/103 Code of Practice for the Assessment of Asset-Specific Losses 3.1 Sept 2011

IMP/001/911 Code of Practice for the Economic Development of Low-Voltage Networks

3.0 March 2014

IMP/001/912 Code of Practice for the Economic Development of the HV System

2.0 March 2014

IMP/001/913 Code of Practice for the Economic Development of the EHV System

2.0 March 2014

IMP/001/914 Code of Practice for the Economic Development of the 132kV System

2.0 March 2014

~O.257 Low Voltage Underground Mains and Services Sept 1996

~O.259 (DRAFT) High Voltage Underground Cable Systems Sept 1996

* DSS/005/040 Standard Current Ratings for 11kV and LV Cables 1.0, 19/03/01

* DSS/005/039 Standard Current Ratings for 33kV and 66kV Cables 1.0, 19/03/01

~ Legacy Northern Electric document

* Legacy Yorkshire Electricity document



4.3 Amendments from previous version

The following table lists the main material changes that have been made between version 1.0 and version 1.1 of this document. It does not include reference to minor changes of negligible impact.

Section Amendments

Appendix 2c. All 33kV ratings from Engineering Recommendation P17 replaced with those published by manufacturers.



5 Definitions

Term Definition

DNO Distribution Network Operator. The person or legal entity named in Part 1 of the Distribution Licence and any permitted legal assigns or successors in title of the named party.

EHV EHV refers to voltages equal to or greater than 33kV and less than 132kV.

HV HV refers to voltages greater than 1000V and less than 33kV.

LV LV refers to voltages less than 1000V.

Northern Powergrid

Northern Powergrid (Northeast) Ltd and Northern Powergrid (Yorkshire) plc.

Continuous rating

The maximum continuous current that can be carried without the maximum conductor temperature being exceeded.

Cyclic rating Rating for a load cycle equivalent to 8 hours at enhanced rating, preceded by 16 hours at half continuous rating and followed by 16 hours at half continuous rating (1.14 x continuous rating)

Emergency rating

Rating for a load cycle equivalent to 3 hours enhanced rating preceded by 12 hours at half of continuous rating followed by 12 hours at half of continuous rating (1.21 x continuous rating)

Cu Copper

Al Aluminium

PVC Polyvinyl chloride

XLPE Cross-linked polyethylene

STA Steel tape armour

SWA Steel wire armoured

AWA Aluminium wire armoured

MDPE Medium density polyethylene

CAS Corrugated aluminium sheath

PE Polyethylene

LSF Low smoke and fume

PPL Paper polythene layer



6 Authority for Issue

6.1 CDS assurance

I sign to confirm that I have completed and checked this document and I am satisfied with its content and submit it for approval and authorisation.

Sign Date

Sarah Phillips CDS Administrator Sarah Phillips 07/10/15

6.2 Author

I sign to confirm that I have completed and checked this document and I am satisfied with its content and submit it for approval and authorisation. Review Period - This document should be reviewed within the following time period.

Standard CDS review of 3 years Non Standard Review Period & Reason

No Period: 1 year

Reason: The move to cable ratings based on a soil thermal resistivity value of 1.5

oC.m/W is under consideration

based on the learning from CLNR.

Sign Date

Ian Fletcher System Planning Engineer Ian Fletcher 30/09/15

6.3 Technical assurance

I sign to confirm that I am satisfied with all aspects of the content and preparation of this document and submit it for approval and authorisation.

Sign Date

Zweli Ndlovu Design Engineer Zweli Ndlovu 30/09/15

Rimnesh Shah Design Engineer Rimnesh Shah 30/09/15

David Gazda Senior Policy and Standards Engineer

David Gazda 30/09/15

.

6.4 Authorisation

Authorisation is granted for publication of this document.

Sign Date

Mark Nicholson Head of System Strategy Mark Nicholson 30/09/15



7 Appendix 1a – Existing LV underground cable ratings All apparent power values quoted using historic values of 240V for single phase cables and 415V for 3 phase cables.

Conductor Construction Current carrying capacity

Continuous Cyclic Emergency

Size (mm2 / in2)

Material Phase conductors

Insulation Sheath Protection A kVA A kVA A kVA

240V Service Cables

4 Cu 1 PVC Concentric PVC 53 12.7 60 14.5 64 15.4

4 Cu 1 PVC Split Conc PVC 53 12.7 60 14.5 64 15.4

0.007 Cu 1 Paper Split Conc 56 13.4 64 15.3 68 16.3

0.007 Cu 2 Paper Lead STA 62 14.9 71 17.0 75 18.0


0.0225 Cu 1 Paper Lead STA 120 28.8 137 32.8 145 34.8

16 Al 1 PVC Split Conc PVC 115 27.6 131 31.5 139 33.4

25 Al 1 PVC Concentric PVC 115 27.6 131 31.5 139 33.4

25 Al 1 PVC Split Conc PVC 150 36.0 171 41.0 182 43.6


0.04 Cu 2 Paper Lead STA 165 39.6 188 45.1 200 47.9

35 Al 1 PVC Concentric PVC 140 33.6 160 38.3 169 40.7

415V Mains Cables

0.0225 Cu 4 Paper Lead STA 100 71.8 114 81.8 121 86.9

25 Cu 4 Paper Lead STA 135 96.9 154 110.5 163 117.3

0.04 Cu 4 Paper Lead STA 140 100.5 160 114.6 169 121.6

35 Al 4 XLPE Waveform PVC 125 89.7 143 102.3 151 108.6

0.1 Al 4 Paper Lead STA 185 132.8 211 151.4 224 160.7

0.1 Cu 4 Paper Lead STA 240 172.3 274 196.4 290 208.5


95 Al 4 Paper Lead STA 225 161.5 257 184.2 272 195.5

0.15 Al 4 Paper Lead STA 225 161.5 257 184.2 272 195.5

0.15 Cu 4 Paper Lead STA 290 208.2 331 237.4 351 251.9


0.02 Cu 4 Paper Lead STA 345 247.7 393 282.4 417 299.7


185 Al 4 Paper Lead STA 330 236.9 376 270.1 399 286.7

0.3 Al 4 Paper Lead STA 350 251.3 399 286.5 424 304.1

0.3 Cu 4 Paper Lead STA 445 319.5 507 364.2 538 386.6


400 Cu 1 Paper Lead PVC 820 588.7 935 671.1 992 712.3

480 Al 1 PVC PVC 590 423.6 673 482.9 714 512.5

600 Al 1 PVC PVC 680 488.2 775 556.6 823 590.7



Appendix 1b – Existing HV underground cable ratings



Size (mm2 / in2)

Material

Phase conductors

Insulation Sheath Protection A MVA A MVA A MVA

11kV

0.1 Al 3 Paper SWA 160 3.04 182 3.47 194 3.68

70 Al 1 XLPE AWA 210 4.0 239 4.6 254 4.8

70 Al 3 XLPE SWA 195 3.7 222 4.2 236 4.5

70 Cu 1 XLPE AWA 270 5.1 308 5.9 327 6.2

70 Cu 3 XLPE SWA 255 4.9 291 5.5 309 5.9

0.125 Cu 6 Paper Lead 250 4.8 285 5.4 303 5.8

95 Al 3 Paper CAS PVC 185 3.52 211 4.01 224 4.26

0.15 Al 3 Paper SWA 195 3.71 222 4.23 236 4.49

120 Al 1 XLPE AWA 280 5.3 319 6.1 339 6.4

120 Al 3 XLPE SWA 265 5.0 302 5.7 321 6.1

120 Cu 1 XLPE AWA 360 6.9 410 7.8 436 8.3

120 Cu 3 XLPE SWA 340 6.5 388 7.4 411 7.8

185 Al 1 XLPE AWA 355 6.8 405 7.7 430 8.2

185 Al 3 Paper CAS PVC 270 5.14 308 5.86 327 6.22

185 Al 3 Paper Lead PVC 280 5.33 319 6.07 339 6.45

185 Al 3 XLPE SWA 335 6.4 382 7.3 405 7.7

185 Al 1 XLPE Triplex MDPE 353 6.7 402 7.7 427 8.1

185 Cu 1 XLPE AWA 455 8.7 519 9.9 551 10.5

185 Cu 3 Paper Lead PVC 346 6.58 394 7.51 419 7.97

185 Cu 3 XLPE SWA 430 8.2 490 9.3 520 9.9

0.3 Al 3 Paper Lead SWA 290 5.52 331 6.29 351 6.68

0.3 Cu 3 Paper Lead SWA 370 7.04 422 8.03 448 8.52

240 Al 3 Paper CAS PVC 315 5.99 359 6.83 381 7.25

240 Al 3 Paper Lead PVC 324 6.17 369 7.03 392 7.46

240 Cu 3 Paper Lead PVC 298 5.67 340 361 6.86

300 Al 1 XLPE AWA 455 8.7 519 9.9 551 10.5

300 Al 3 Paper CAS PVC 355 6.76 405 7.70 430 8.17

300 Al 3 XLPE SWA 435 8.3 496 9.4 526 10.0

300 Cu 1 Paper Lead PVC 530 10.1 604 11.5 641 12.2

300 Cu 1 XLPE AWA 580 11.0 661 12.6 702 13.4

300 Cu 3 Paper CAS PVC 446 8.49 508 9.68 540 10.27

300 Cu 3 XLPE SWA 540 10.3 616 11.7 653 12.4


300 Cu 1 XLPE Triplex MDPE 616 11.7 702 13.4 745 14.2

0.5 Al 3 Paper SWA 375 7.14 428 8.14 454 8.63

0.5 Cu 1 Paper Lead 525 9.99 599 11.4 635 12.1


400 Cu 1 Paper Lead PVC 600 11.4 684 13.0 726 13.8

20kV

95 Al 1 - triplex XLPE MDPE MDPE 245 8.48 279 9.66 296 10.26


400 Cu 1 - triplex XLPE MDPE MDPE 690 23.87 787 27.22 835 28.89

400 Cu 1 XLPE MDPE MDPE 670 23.18 764 26.43 811 28.05



Appendix 1c – Existing 33kV and 66kV underground cable ratings Conductor Construction Current carrying capacity


Size (mm2 / in2)



33kV

0.1 Cu 1 Paper Lead 210 12.0 239 13.7 254 14.5

0.15 Cu 1 Paper Lead 265 15.1 302 17.2 321 18.3

0.15 Cu 3 Paper Lead 276 15.8 315 18.0 334 19.1

0.2 Cu 1 Paper Lead 300 17.1 342 19.5 363 20.7

0.2 Cu 3 Gas CAS 340 19.4 388 22.1 411 23.5

0.2 Cu 3 Oil CAS 340 19.4 388 22.1 411 23.5

0.2 Cu 3 Oil Lead 340 19.4 388 22.1 411 23.5

0.2 Cu 3 Paper Copper 290 16.6 331 18.9 351 20.0

0.2 Cu 3 Paper Lead 290 16.6 331 18.9 351 20.0

0.25 Cu 1 Oil Lead 390 22.3 445 25.4 472 26.9

0.25 Cu 1 Paper Copper 345 19.7 393 22.5 417 23.8

0.25 Cu 3 Oil Lead 390 22.3 445 25.4 472 26.9

0.25 Cu 3 Paper Lead 335 19.1 382 21.8 405 23.1

185 Al 1 Paper Lead 300 17.1 342 19.5 363 20.7

185 Al 1 XLPE Screened PVC 360 20.6 410 23.4 436 24.9

185 Cu 1 Paper Lead 385 22.0 439 25.1 466 26.6

185 Cu 1 XLPE Screened PVC 460 26.3 524 29.9 557 31.8

185 Cu 1 XLPE SWA 450 25.7 513 29.3 545 31.1

185 Cu 3 Paper Lead 404 23.1 461 26.3 489 27.9

185 Cu 3 XLPE SWA 420 24.0 479 27.3 508 29.0

0.3 Al 1 Paper Copper 300 17.1 342 19.5 363 20.7

0.3 Al 1 Paper Lead 300 17.1 342 19.5 363 20.7

0.3 Al 3 Gas Aluminium 330 18.8 376 21.5 399 22.8

0.3 Al 3 Oil Aluminium 340 19.4 388 22.1 411 23.5

0.3 Al 3 Paper Lead 290 16.6 331 18.9 351 20.0

0.3 Cu 1 Paper Copper 380 21.7 433 24.7 460 26.2

0.3 Cu 1 Paper Lead 380 21.7 433 24.7 460 26.2

0.3 Cu 3 Gas Aluminium 365 20.8 416 23.8 442 25.2

0.3 Cu 3 Gas CAS 420 24.0 479 27.3 508 29.0

0.3 Cu 3 Gas Lead 365 20.8 416 23.8 442 25.2

0.3 Cu 3 Oil CAS 430 24.5 490 28.0 520 29.7

0.3 Cu 3 Oil Lead 435 24.8 496 28.3 526 30.0

0.3 Cu 3 Paper CAS 360 20.6 410 23.4 436 24.9

0.3 Cu 3 Paper Lead 365 20.8 416 23.8 442 25.2


240 Al 3 Oil Aluminium 370 21.1 422 24.1 448 25.6

240 Al 3 Paper Lead 445 25.4 507 29.0 538 30.7

240 Cu 1 Paper Aluminium 445 25.4 507 29.0 538 30.7

240 Cu 1 Paper Lead 415 23.7 473 27.0 502 28.7

240 Cu 1 PVC 445 25.4 507 29.0 538 30.7


240 Cu 1 XLPE SWA 510 29.1 581 33.2 617 35.2

240 Cu 3 Gas Aluminium 470 26.8 536 30.6 569 32.5

240 Cu 3 Oil Aluminium 475 27.1 542 30.9 575 32.8

240 Cu 3 Oil CAS 475 27.1 542 30.9 575 32.8


240 Cu 3 Paper Lead 463 26.4 528 30.1 560 32.0

240 Cu 3 XLPE SWA 480 27.4 547 31.2 581 33.2

0.4 Al 1 Paper Lead 345 19.7 393 22.5 417 23.8

0.4 Al 3 Gas Aluminium 385 22.0 439 25.1 466 26.6

0.4 Al 3 Gas Lead 385 22.0 439 25.1 466 26.6





Size (mm2 / in2)



33kV

0.4 Al 3 Oil Aluminium 390 22.3 445 25.4 472 26.9

0.4 Al 3 Oil Lead 405 23.1 462 26.4 490 28.0

0.4 Al 3 Paper Lead 330 18.8 376 21.5 399 22.8

0.4 Cu 1 Paper Lead 440 25.1 502 28.6 532 30.4

0.4 Cu 3 Gas Aluminium 415 23.7 473 27.0 502 28.7

0.4 Cu 3 Gas CAS 485 27.7 553 31.6 587 33.5

0.4 Cu 3 Gas Lead 415 23.7 473 27.0 502 28.7

0.4 Cu 3 Oil Aluminium 495 28.3 564 32.2 599 34.2

0.4 Cu 3 Oil CAS 495 28.3 564 32.2 599 34.2

0.4 Cu 3 Oil Lead 505 28.8 576 32.9 611 34.9

0.4 Cu 3 Paper Aluminium 420 24.0 479 27.3 508 29.0

0.4 Cu 3 Paper Lead 420 24.0 479 27.3 508 29.0

0.45 Cu 3 Paper Lead 435 24.8 496 28.3 526 30.0

300 Al 1 Paper Aluminium 395 22.6 450 25.7 478 27.3




300 Cu 1 Paper CAS 490 28.0 559 31.9 593 33.8

300 Cu 1 Paper Copper 500 28.5 570 32.5 605 34.5

300 Cu 1 Paper Lead 500 28.5 570 32.5 605 34.5

300 Cu 1 Paper PVC 500 28.5 570 32.5 605 34.5


300 Cu 1 XLPE SWA 570 32.5 650 37.1 690 39.4

300 Cu 3 Oil Aluminium 475 27.1 542 30.9 575 32.8

300 Cu 3 Oil Lead 515 29.4 587 33.5 623 35.6


300 Cu 3 Paper Lead 465 26.5 530 30.3 563 32.1

300 Cu 3 XLPE SWA 530 30.3 604 34.5 641 36.6

0.5 Al 1 Oil Aluminium 440 25.1 502 28.6 532 30.4

0.5 Al 1 Oil Lead 457 26.1 521 29.7 553 31.6

0.5 Al 1 Paper Aluminium 390 22.3 445 25.4 472 26.9

0.5 Al 1 Paper Lead 390 22.3 445 25.4 472 26.9

0.5 Al 3 Gas Aluminium 425 24.3 485 27.7 514 29.4

0.5 Al 3 Oil Aluminium 457 26.1 521 29.7 553 31.6

0.5 Al 3 Paper Lead 365 20.8 416 23.8 442 25.2

0.5 Cu 1 Gas CAS 535 30.5 610 34.8 647 37.0

0.5 Cu 1 Gas Lead 535 30.5 610 34.8 647 37.0

0.5 Cu 1 Oil CAS 540 30.8 616 35.1 653 37.3

0.5 Cu 1 Paper Aluminium 490 28.0 559 31.9 593 33.8

0.5 Cu 1 Paper Copper 490 28.0 559 31.9 593 33.8

0.5 Cu 1 Paper Lead 490 28.0 559 31.9 593 33.8

0.5 Cu 3 Gas Aluminium 470 26.8 536 30.6 569 32.5

0.5 Cu 3 Gas Lead 470 26.8 536 30.6 569 32.5

0.5 Cu 3 Oil Aluminium 550 31.4 627 35.8 666 38.0

0.5 Cu 3 Oil CAS 550 31.4 627 35.8 666 38.0

0.5 Cu 3 Oil Lead 560 32.0 638 36.4 678 38.7

0.5 Cu 3 Paper Lead 460 26.3 524 29.9 557 31.8

350 Cu 3 Oil Aluminium 575 32.8 656 37.4 696 39.7

0.6 Al 1 Paper Lead 430 24.5 490 28.0 520 29.7

0.6 Al 3 Gas Aluminium 460 26.3 524 29.9 557 31.8

0.6 Al 3 Gas Lead 460 26.3 524 29.9 557 31.8

0.6 Al 3 Oil Aluminium 475 27.1 542 30.9 575 32.8

0.6 Al 3 Oil CAS 475 27.1 542 30.9 575 32.8





Size (mm2 / in2)



33kV

0.6 Al 3 Oil Lead 500 28.5 570 32.5 605 34.5

0.6 Al 3 Paper Lead 410 23.4 467 26.7 496 28.3

0.6 Cu 1 Paper Lead 565 32.3 644 36.8 684 39.0

0.6 Cu 3 Gas Aluminium 570 32.5 650 37.1 690 39.4

0.6 Cu 3 Gas Lead 570 32.5 650 37.1 690 39.4

0.6 Cu 3 Oil Aluminium 600 34.3 684 39.0 726 41.4

0.6 Cu 3 Oil CAS 600 34.3 684 39.0 726 41.4

0.6 Cu 3 Oil Lead 615 35.1 701 40.0 744 42.5

0.6 Cu 3 Paper Lead 515 29.4 587 33.5 623 35.6



400 Al 3 Gas Aluminium 475 27.1 542 30.9 575 32.8

400 Al 3 Oil Aluminium 480 27.4 547 31.2 581 33.2

400 Cu 1 Oil Aluminium 600 34.3 684 39.0 726 41.4


400 Cu 3 Gas Aluminium 585 33.4 667 38.1 708 40.4

400 Cu 3 Oil CAS 595 34.0 678 38.7 720 41.1

400 Cu 3 Paper Lead 570 32.5 650 37.1 690 39.4

0.75 Al 1 Paper Lead 505 28.8 576 32.9 611 34.9

0.75 Cu 1 Paper Lead 620 35.4 707 40.4 750 42.8

500 Al 1 Paper Lead 510 29.1 581 33.2 617 35.2



630 Al 1 Paper Lead 580 33.1 661 37.7 702 40.1


630 Al 3 Gas Aluminium 590 33.7 673 38.4 714 40.8

630 Al 3 Oil Aluminium 595 34.0 678 38.7 720 41.1


1 Al 3 Oil Aluminium 615 35.1 701 40.0 744 42.5

1 Cu 1 Paper Lead 710 40.5 809 46.2 859 49.0



1.5 Cu 1 Paper Lead 990 56.5 1129 64.4 1198 68.4





Size (mm2 / in2)



66kV

0.15 Cu 3 Oil Lead 295 33.7 336 38.4 357 40.8

0.2 Cu 1 Oil Lead 350 40.0 399 45.6 424 48.4

0.2 Cu 3 Oil Lead 335 38.3 382 43.6 405 46.3

150 Al 1 XLPE CAS PVC 360 41.1 410 46.9 436 49.7

185 Cu 1 XLPE CAS PVC 405 46.2 462 52.7 490 56.0

185 Cu 1 XLPE Lead PVC 460 52.5 524 59.9 557 63.6

0.3 Cu 1 Oil Lead 440 50.2 502 57.3 532 60.8

0.3 Cu 3 Oil Lead 425 48.5 485 55.3 514 58.7

240 Cu 1 Oil Aluminium 470 53.7 536 61.2 569 64.9

240 Cu 1 Oil Lead 495 56.5 564 64.4 599 68.4

240 Cu 1 XLPE CAS PVC 465 53.1 530 60.5 563 64.2

240 Cu 1 XLPE Lead PVC 525 59.9 599 68.3 635 72.5





Size (mm2 / in2)



66kV

0.4 Cu 1 Oil Lead 505 57.7 576 65.7 611 69.8

0.4 Cu 3 Oil Lead 490 55.9 559 63.8 593 67.7

0.45 Cu 1 Oil Aluminium 510 58.2 581 66.4 617 70.5

300 Cu 1 XLPE CAS 515 58.8 587 67.0 623 71.2

300 Cu 1 XLPE Lead PVC 585 66.8 667 76.1 708 80.8

300 Cu 1 Oil CAS 520 59.4 593 67.7 629 71.8

300 Cu 3 Oil Lead 540 61.7 616 70.3 653 74.6

0.5 Cu 1 Oil Lead 565 64.5 644 73.5 684 78.1

0.6 Cu 1 Oil Aluminium 555 63.4 633 72.2 672 76.7

0.6 Cu 1 Oil Lead 620 70.8 707 80.7 750 85.7

400 Cu 1 XLPE CAS PVC 575 65.7 656 74.8 696 79.4

400 Cu 1 XLPE Lead PVC 660 75.4 752 85.9 799 91.2

500 Cu 1 XLPE Lead PVC 740 84.5 844 96.3 895 102.2



Appendix 1d – Existing 132kV underground cable ratings Conductor Construction Current carrying capacity


Size (mm2 / in2)



132kV

0.2 Cu 3 Oil Lead 335 76.5 382 87.2 405 92.6

185 Cu 1 XLPE CAS PVC 305 69.6 348 79.4 369 84.3

0.3 Cu 1 Oil Lead 430 98.2 490 112 520 119

0.35 Cu 1 Oil Lead 460 105 524 120 557 127

240 Cu 1 Oil Aluminium 453 103 516 118 548 125

0.4 Cu 1 Oil Lead 495 113 564 129 599 137

0.4 Cu 3 Oil Lead 495 113 564 129 599 137

260 Cu 1 Oil Aluminium 465 106 530 121 563 128

0.45 Cu 1 Oil Aluminium 490 112 559 128 593 135

300 Cu 1 Oil CAS 496 113 565 129 600 137

300 Cu 1 XLPE CAS PVC 495 113 564 129 599 137

300 Cu 1 XLPE Lead PVC 575 131 656 150 696 159

0.5 Cu 1 Oil Lead 545 124 621 142 659 151

0.5 Cu 3 Oil Lead 550 126 627 143 666 152

0.55 Cu 1 Oil Lead 575 131 656 150 696 159

0.6 Cu 1 Oil Aluminium 550 126 627 143 666 152

0.6 Cu 1 Oil Lead 595 136 678 155 720 164

0.6 Cu 3 Oil Lead 605 138 690 157 732 167

400 Cu 1 Oil Aluminium 561 128 640 146 679 155

400 Cu 1 XLPE CAS PVC 555 127 633 144 672 153

400 Cu 1 XLPE Lead PVC 650 148 741 169 787 180

0.75 Cu 1 Oil Aluminium 595 136 678 155 720 164

0.75 Cu 1 Oil Lead 655 150 747 171 793 181

500 Al 1 XLPE CAS PVC 510 116 581 133 617 141

500 Cu 1 Oil Aluminium 603 138 687 157 730 167

500 Cu 1 XLPE CAS PVC 615 140 701 160 744 170

500 Cu 1 XLPE Lead PVC 725 166 827 189 877 200

0.85 Cu 1 Oil Lead 690 158 787 180 835 191

630 Cu 1 XLPE CAS PVC 675 154 770 176 817 187

630 Cu 1 XLPE Lead PVC 815 186 929 212 986 225

1 Cu 1 Oil Aluminium 660 151 752 172 799 182

1 Cu 1 Oil Lead 745 170 849 194 901 206

800 Cu 1 XLPE CAS PVC 750 171 855 195 908 207

800 Cu 1 XLPE Lead PVC 890 203 1015 232 1077 246

1.25 Cu 1 Oil Aluminium 925 211 1055 241 1119 256

1.5 Cu 1 Oil Lead 975 223 1112 254 1180 269

1000 Cu 1 XLPE CAS PVC 800 183 912 208 968 221

1000 Cu 1 XLPE Lead PVC 960 219 1094 250 1162 265

1.75 Cu 1 Oil Lead 1120 256 1277 292 1355 309

0.65 Cu 3 Gas Compression Lead 544 124

0.65 Cu 3 Gas Compression PE 562 128



Appendix 2a – New LV cable ratings Equivalent apparent power based on single phase equivalent for all single conductor cables except 630Cu and 800Cu XLPE which has three phase apparent power quoted. All three core cables have three phase apparent power quoted. All apparent power values quoted are based on 230V for single phase use and 400V for three phase use.

All ratings taken from manufacturer’s cable data.



Size (mm2)


Insulation Sheath Protection A kVA A kVA A kVA

Laid direct

35 Al 1 XLPE Conc PVC 150 34.5 171 39.3 182 41.7

35 Al 3 XLPE Conc PVC 130 90.0 148 102.6 157 108.9

95 Al 3 XLPE Conc PVC 245 169.5 279 193.3 296 205.1

185 Al 3 XLPE Conc PVC 355 245.7 405 280.1 430 297.2

300 Al 3 XLPE Conc PVC 465 321.8 530 366.8 563 389.4

630 Cu 1 XLPE Conc PVC 841 582.0 959 663.4 1018 704.2

800 Cu 1 XLPE Conc PVC 888 614.5 1012 700.5 1074 743.5

Ducted

35 Al 1 XLPE Conc PVC 125 28.8 143 32.8 151 34.8

35 Al 3 XLPE Conc PVC 105 72.7 120 82.8 127 87.9

95 Al 3 XLPE Conc PVC 205 141.9 234 161.7 248 171.7

185 Al 3 XLPE Conc PVC 300 207.6 342 236.7 363 251.2

300 Al 3 XLPE Conc PVC 395 273.3 450 311.6 478 330.7

630 Cu 1 XLPE Conc PVC 664 459.5 757 523.8 803 556.0

800 Cu 1 XLPE Conc PVC 692 478.9 789 545.9 837 579.4



Appendix 2b – New HV cable ratings

HV cable ratings

All values quoted for flat spaced installation, individual ducts where ducted. Triplex cable consists of three twisted single cores, one single-way duct where quoted. One cable diameter spacing between cables assumed for laid direct and one duct diameter spacing between ducts assumed for ducted single cores. Ducted ratings for 400Cu 20kV triplex cables available on request from the Asset Management Underground Cables Engineer.



Size (mm2) Material Phase conductors


Laid direct

11kV8

185 Al 1 XLPE MDPE MDPE 368 7.0 419 8.0 445 8.5

300 Cu 1 XLPE MDPE MDPE 583 11.1 665 12.6 705 13.4

400 Cu 1 XLPE MDPE MDPE 652 12.4 743 14.1 789 15.0

500 Cu 1 XLPE MDPE MDPE 725 13.8 826 15.7 877 16.7

630 Cu 1 XLPE MDPE MDPE 802 15.3 914 17.4 970 18.5





20kV9




400 Cu 1 XLPE MDPE MDPE 670 23.2 764 26.4 811 28.1

Ducted

11kV

185 Al 1 XLPE MDPE MDPE 351 6.7 400 7.6 456 8.7

300 Cu 1 XLPE MDPE MDPE 540 10.3 616 11.7 702 13.4

400 Cu 1 XLPE MDPE MDPE 595 11.3 679 12.9 774 14.7

500 Cu 1 XLPE MDPE MDPE 659 12.5 751 14.3 856 16.3

630 Cu 1 XLPE MDPE MDPE 730 13.9 832 15.8 949 18.1





20kV



400 Cu 1 - triplex XLPE MDPE MDPE - - - - - -

400 Cu 1 XLPE MDPE MDPE 590 20.4 673 23.3 714 24.7

8 All 11kV cable ratings are taken from tables 6-7 and 6-8 on pages 70 and 71 of Engineering Recommendation P17 part 3:

Ratings for 11kV and 33kV cables having extruded insulation, issue 1, 2004 and have been de-rated for a soil thermal resistivity of 1.2

oC.m/W and ground temperature of 15

oC using the de-rating factors contained in tables 6-17, 6-19 and 7-1

respectively.

9 All ratings taken from manufacturer’s cable data.



Appendix 2c – New 33kV cable ratings

All ratings quoted for trefoil formation and based on manufacturers continuous ratings.





Nexans cable data

Laid direct

240 Cu 1 XLPE MDPE MDPE 530.0 30.3 604 34.5 641 36.6

300 Cu 1 XLPE MDPE MDPE 600.0 34.3 684 39.0 726 41.4

400 Cu 1 XLPE MDPE MDPE 690.0 39.4 787 44.9 835 47.7

500 Cu 1 XLPE MDPE MDPE 760.0 43.4 866 49.5 920 52.5

630 Cu 1 XLPE MDPE MDPE 850.0 48.5 969 55.3 1029 58.7

Ducted

240 Cu 1 XLPE MDPE MDPE 520.0 29.7 593 33.8 629 35.9

300 Cu 1 XLPE MDPE MDPE 570.0 32.5 650 37.1 690 39.4

400 Cu 1 XLPE MDPE MDPE 630.0 36.0 718 41.0 762 43.5

500 Cu 1 XLPE MDPE MDPE 700.0 40.0 798 45.6 847 48.4

630 Cu 1 XLPE MDPE MDPE 780.0 44.5 889 50.8 944 53.9





Prysmian cable data

Laid direct

240 Cu 1 XLPE MDPE MDPE 525 30.0 599 34.2 635 36.3

300 Cu 1 XLPE MDPE MDPE 590 33.7 673 38.4 714 40.8

400 Cu 1 XLPE MDPE MDPE 760 43.4 866 49.5 920 52.5

500 Cu 1 XLPE MDPE MDPE 850 48.5 969 55.3 1029 58.7

630 Cu 1 XLPE MDPE MDPE 940 53.7 1072 61.2 1137 64.9

Ducted

240 Cu 1 XLPE MDPE MDPE 480 27.4 547 31.2 581 33.2

300 Cu 1 XLPE MDPE MDPE 535 30.5 610 34.8 647 37.0

400 Cu 1 XLPE MDPE MDPE 600 34.3 684 39.0 726 41.4

500 Cu 1 XLPE MDPE MDPE 670 38.3 764 43.6 811 46.3

630 Cu 1 XLPE MDPE MDPE 750 42.8 855 48.8 908 51.8



Appendix 3a – De-rating factors for depth

Depth of laying LV cables 11kV and 33kV cables

(m) Up to 50mm2

70mm2 to 300mm

2 Above 300mm

2 Up to 300mm

2 Above

300mm2

0.50 1.00 1.00 1.00 - -

0.60 0.99 0.98 0.97 - -

0.80 0.97 0.96 0.94 1.00 1.00

1.00 0.95 0.94 0.92 0.98 0.97

1.25 0.94 0.92 0.90 0.96 0.95

1.50 0.93 0.91 0.89 0.95 0.94

1.75 0.92 0.89 0.87 0.94 0.92

2.00 0.91 0.88 0.86 0.92 0.90

2.50 0.90 0.87 0.85 0.91 0.89

Greater than 3.00

0.89 0.86 0.83 0.90 0.88



Appendix 3b – De-rating factors for thermal resistivity of soil

Cable type and laying conditions

Soil thermal resistivity, average value in oC.m/W

0.8 0.9 1.0 1.5 2.0 2.5 3.0

Three core

Up to 16mm2

1.09 1.06 1.04 0.95 0.86 0.79 0.74

25mm2 to

150mm2

1.14 1.10 1.07 0.93 0.84 0.76 0.70

185mm2 to

400mm2

1.16 1.11 1.07 0.92 0.82 0.74 0.68

Single core

Up to 150mm2

1.16 1.11 1.07 0.91 0.81 0.73 0.67

185mm2 to

400mm2

1.17 1.12 1.07 0.90 0.80 0.72 0.66

500mm2 to

1200mm2

1.18 1.13 1.08 0.9 0.79 0.71 0.65



Appendix 3c – De-rating factors for ambient temperature

Cable insulation

Max conductor operating temperature

oC

Ground temperature oC

10 15 20 25 30 35 40 45

Paper 65 1.05 1.00 0.95 0.89 0.84 0.77 0.71 0.63

Paper 70 1.04 1.00 0.95 0.90 0.85 0.80 0.74 0.67

Paper 75 1.04 1.00 0.96 0.92 0.88 0.83 0.78 0.73

PVC 70 1.04 1.00 0.95 0.90 0.85 0.80 0.74 0.67



Appendix 3d – De-rating factors for proximity, single cores laid direct

Voltage

No of ccts

Spacing (between cable centres)

Touching

Trefoil Laid flat 0.15m 0.3m 0.45m 0.6m 0.76m 0.91m

230 / 400V

2 0.77 0.80 0.82 0.88 0.90 0.93

3 0.65 0.68 0.72 0.79 0.83 0.87

4 0.59 0.63 0.67 0.75 0.81 0.85

5 0.55 0.58 0.63 0.72 0.78 0.83

6 0.52 0.56 0.60 0.70 0.77 0.82

11kV

2 0.78 0.80 0.81 0.85 0.88 0.90

3 0.66 0.69 0.71 0.76 0.80 0.83

4 0.60 0.63 0.65 0.72 0.76 0.80

5 0.55 0.58 0.61 0.68 0.73 0.77

6 0.52 0.55 0.58 0.66 0.72 0.76

33kV

2 0.79 0.81 0.81 0.85 0.88 0.90 0.93 0.95

3 0.67 0.70 0.71 0.76 0.80 0.83 0.87 0.90

4 0.62 0.65 0.65 0.72 0.76 0.80 0.83 0.88

5 0.57 0.60 0.60 0.68 0.73 0.77

6 0.54 0.57 0.57 0.66 0.72 0.76



Appendix 3e – De-rating factors for proximity, single cores laid in ducts

Voltage

No of ccts

Spacing (between duct centres)

Touching 0.3m 0.45m 0.6m 0.76m 0.91m

230 / 400V

2 0.86 0.90 0.93

3 0.77 0.83 0.87

4 0.73 0.81 0.85

5 0.70 0.78 0.83

6 0.68 0.77 0.82

11kV

2 0.85 0.88 0.90

3 0.75 0.80 0.83

4 0.70 0.76 0.80

5 0.67 0.73 0.77

6 0.64 0.71 0.76

33kV

2 0.85 0.88 0.90 0.94 0.96

3 0.76 0.80 0.83 0.88 0.91

4 0.71 0.76 0.80 0.85 0.88

5 0.67 0.73 0.77

6 0.65 0.71 0.76



Appendix 3f – De-rating factors for proximity, multi-core cables laid direct

Voltage

No of ccts

Spacing (between cable centres)

Touching 0.15m 0.3m 0.45m 0.6m 0.76m 0.91m

230 / 400V

2 0.81 0.87 0.91 0.93 0.94

3 0.70 0.78 0.84 0.87 0.90

4 0.63 0.74 0.81 0.86 0.89

5 0.59 0.70 0.78 0.83 0.87

6 0.55 0.67 0.76 0.82 0.86

11kV

2 0.80 0.85 0.89 0.90 0.92

3 0.69 0.75 0.80 0.84 0.86

4 0.63 0.70 0.77 0.80 0.84

5 0.57 0.66 0.73 0.78 0.81

6 0.55 0.63 0.71 0.76 0.80

33kV

2 0.80 0.83 0.87 0.89 0.91 0.94 0.95

3 0.70 0.73 0.78 0.82 0.85 0.88 0.90

4 0.64 0.68 0.74 0.78 0.82 0.85 0.88

5 0.59 0.63 0.70 0.75 0.79

6 0.56 0.60 0.68 0.74 0.78



Appendix 3g – De-rating factors for proximity, multi-core cables laid in ducts

Voltage

No of ccts

Spacing (between duct centres)

Touching 0.3m 0.45m 0.6m 0.76m 0.91m

230 / 400V

2 0.90 0.93 0.95 0.96

3 0.82 0.87 0.90 0.93

4 0.78 0.85 0.89 0.91

5 0.75 0.82 0.87 0.90

6 0.72 0.81 0.86 0.90

11kV

2 0.88 0.91 0.93 0.94

3 0.80 0.84 0.87 0.89

4 0.75 0.81 0.84 0.87

5 0.71 0.77 0.82 0.85

6 0.69 0.75 0.80 0.84

33kV

2 0.87 0.89 0.92 0.93 0.95 0.96

3 0.78 0.82 0.85 0.87 0.92 0.94

4 0.73 0.78 0.82 0.85 0.90 0.92

5 0.69 0.75 0.79 0.83

6 0.67 0.73 0.73 0.82

Documents

IMP/001/013 Document TypeDocument reference Version:- …IMP/001/013 1.0 Code of Practice for Guidance on the Selection of Underground Cable Ratings 2 Scope The ratings stated in this