IMP/001/011 Code of Practice for Guidance on the … - August 1987 NEEB Engineering Instruction ER...

Document reference IMP/001/011 Document Type Code of Practice

Version:- 3.0 Date of Issue:- September 2015 of 28

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 - This document may be out of date if printed

IMP/001/011 – Code of Practice for Guidance on the Selection of Overhead Line Ratings

1. Purpose

The purpose of this document is to provide guidance on the selection of ratings to be applied to overhead lines on the Northern Powergrid distribution system.

This document describes key assumptions made in the preparation of this document and also provides clarity across the organisation with respect to alignment of overhead line rating policies across legacy companies.

This code of practice primarily helps to ensure that Northern Powergrid achieves its requirements with respect to the Electricity Safety, Quality, and Continuity (ESQC) Regulations 2002, Distribution Licences and The Distribution Code, by laying out the way in which overhead line ratings shall be applied to the distribution system. Correctly applying ratings to overhead line circuits allows the facilitation and optimisation of planning, design and connection requirements for the distribution system.

This document supersedes the following documents, all copies of which should be destroyed.

Ref Version Date Title

IMP/001/011 2.1 July 2007 Code of Practice for Guidance on the Selection of Overhead Line Ratings

IMP/001/011 1.0 December 2005 Code of Practice for Guidance on the Selection of Overhead Line Ratings

DSS/004/039 1.0 March 2000 Guidance Note for Overhead Line ratings

Overhead Line Manual

- January 1993 Part 1, Section 7 “Overhead Line Ratings”.

132kV Overhead Line Manual

- - Part 7, Section 6.6 “Ratings”.

E722 - August 1987 NEEB Engineering Instruction ER P27 Current Rating Guide for High Voltage Overhead Lines

2. Scope

The document applies to Northern Powergrid (Northeast) Limited and Northern Powergrid (Yorkshire) plc the licensed distributors of Northern Powergrid (these terms will be used interchangeably through this document).

This document applies to all overhead line conductors utilised at the following operating voltages:

415V, Low Voltage (LV)

5.25kV to 20kV, High Voltage (HV),

33kV and 66kV, Extra High Voltage (EHV); and

132kV.




This document applies to the overhead line portion of a circuit only, and must not be assumed to apply to associated equipment (e.g. transformers or underground cables) or in general to be a rating specification to be met by the associated equipment.

The document details harmonised Northern Powergrid rating information for new and existing overhead lines. Where these thermal circuit ratings are influenced by a respective overhead line specification, guidance is given in this document as to what rating to adopt under those conditions.

It provides information relating to the capability of overhead line conductors, specifying the maximum thermal rating capabilities for specific overhead line design configurations. The ratings are given for conductor maximum design temperatures of 50

OC, 65

OC and 75

OC depending on the type of overhead line construction under

consideration. Ratings are given for winter, spring/autumn and summer conditions in both amps and MVA (at nominal design voltage).

This document does not specify:

Guidance relating to the relevant overhead line design specifications that shall be utilised for new build or refurbishment of overhead lines.

Guidance relating to the size and type of conductor that should be utilised for a specific application.

Guidance relating to the methods available to up-rate existing overhead lines.

Guidance relating to the required statutory overhead line clearances. New build overhead line clearances shall be to NSP/004/011 “Code of Practise for Overhead Line Clearances” .

Guidance relating to sag and tension calculations.




2.1. Table of Contents 1. Purpose ................................................................................................................................................................. 1 2. Scope .................................................................................................................................................................... 1

2.1. Table of Contents ........................................................................................................................................................... 3 3. Code of Practise .................................................................................................................................................... 4

3.1. Assessment of Relevant Drivers .................................................................................................................................... 4 3.1.1. Internal Drivers ........................................................................................................................................................ 4 3.1.2. External Drivers ....................................................................................................................................................... 4 3.1.2.1. Electricity Safety, Quality, and Continuity Regulations 2002 ................................................................................. 4 3.1.2.2. Distribution Licence................................................................................................................................................. 5 3.1.2.3. Distribution Code ..................................................................................................................................................... 5 3.2. Key Requirements.......................................................................................................................................................... 5 3.3. Overhead Line Ratings .................................................................................................................................................. 5 3.3.1. Guidance on the Selection of Overhead Line Conductor Rating ............................................................................. 5 3.3.1.1. Percentage Excursion Time ..................................................................................................................................... 5 3.3.1.2. Weather Conditions ................................................................................................................................................. 6 3.3.1.3. Modes of Operation ................................................................................................................................................. 6 3.3.1.4. Single Circuit Radial and Secondary Distribution (Ring) Systems.......................................................................... 6 3.3.1.5. Multi-Circuit Primary Supply Systems .................................................................................................................... 6 3.3.1.6. 132kV Systems ........................................................................................................................................................ 7 3.3.2. Limiting Factors for the Applied Rating .................................................................................................................. 7 3.3.2.1. Thermal Limitations and Overhead Line Design Specifications ............................................................................. 7 3.3.2.2. Historical Overhead Line Design Specifications ..................................................................................................... 7 3.3.2.3. New Build Overhead Line Design Specifications.................................................................................................... 9 3.3.2.4. Conductor Type ..................................................................................................................................................... 10 3.3.2.5. Conductor Fittings Type ........................................................................................................................................ 10 3.3.3. Overhead Line Ratings .......................................................................................................................................... 11 3.3.3.1. 132kV Ratings (Amps) .......................................................................................................................................... 11 3.3.3.2. 132kV Ratings (MVA) .......................................................................................................................................... 12 3.3.3.3. 66kV Ratings (Amps) ............................................................................................................................................ 13 3.3.3.4. 66kV Ratings (MVA) ............................................................................................................................................ 14 3.3.3.5. 33kV Ratings (Amps) ............................................................................................................................................ 15 3.3.3.6. 33kV Ratings (MVA) ............................................................................................................................................ 16 3.3.3.7. HV (5.25kv to 20kV) Ratings (Amps) ................................................................................................................... 18 3.3.3.8. 11kV Ratings (MVA) ............................................................................................................................................ 20 3.3.3.9. 20kV Ratings (MVA) ............................................................................................................................................ 22 3.3.3.10. LV Ratings (Amps) ........................................................................................................................................... 24

4. References .......................................................................................................................................................... 25 4.1. External Documentation .............................................................................................................................................. 25 4.2. Internal Documentation ............................................................................................................................................... 25 4.3. Summary of Amendments ........................................................................................................................................... 26

5.0 Definitions ............................................................................................................................................................ 26 6. Authority for issue .............................................................................................................................................. 28

6.1. CDS Assurance ............................................................................................................................................................ 28 6.2. Author .......................................................................................................................................................................... 28 6.3. Technical Assurance .................................................................................................................................................... 28 6.4. Authorisation ............................................................................................................................................................... 28




3. Code of Practise

3.1. Assessment of Relevant Drivers

3.1.1. Internal Drivers The key internal business drivers relating to the correct selection and application of overhead line ratings are:

Safety,

Financial; and

Quality of supply.

These internal drivers are of paramount importance and the appropriate selection of ratings helps satisfy these drivers. It does this by facilitating the provision of a safe, cost effective and secure supply of electricity to customers in line with the requirements of legislation.

3.1.2. External Drivers

3.1.2.1. Electricity Safety, Quality, and Continuity Regulations 2002 The principal external driver relating to applying the correct rating to overhead lines is the Electricity, Safety, Quality and Continuity (ESQC) Regulations 2002 (Statutory Instrument no. 2665). All overhead lines shall meet the requirements of these regulations.

The ESQC Regulations impose a number of obligations on the business, mainly relating to safety and quality of supply. Unlike overhead line regulations previously in force (detailed in section 3.3.2.2), the ESQC Regulations do not set specific mechanical design requirements for overhead lines. Instead, Regulation Numbers 3(1) (a) and 3(1) (b) details the general adequacy of electrical equipment. These regulations state that;

“…distributors…shall ensure that their equipment is sufficient for the purposes for and the circumstances in which it is used; and so constructed, installed…used as to prevent danger…or interruption of supply, so far as is reasonably practicable.”

All overhead lines shall be assigned a rating in line with this guidance document which will contribute to compliance with the ESQC Regulations. The code of practice achieves this by:

Defining the ratings that should be adopted for specific overhead lines to ensure they are sufficient for the circumstances in which they are used,

Defining the ratings that should be adopted for specific overhead line conductors to ensure they are installed and used as to prevent danger (due to overloading); and

Ensuring conductors are adequately operated for their application, avoiding the risk of overloading by defining permissible overhead line circuit ratings so as to prevent any interruption of supply.

In addition, ESQC Regulation Number (17) requires that;

“…the height above ground of any overhead line, at the maximum likely temperature of that line, shall not be less than that specified…”

The key issue for this code of practice is ensure lines are appropriately rated to secure that statutory clearances are not ‘likely’ to be infringed.




3.1.2.2. Distribution Licence Additional external business drivers relating to applying the correct rating to overhead lines are the Distribution Licences applicable to Northern Powergrid .

The Distribution Licences held by Northern Powergrid require that the distribution system is planned and developed to a standard of security not less than that laid down in the latest revision of Engineering Recommendation (ER) P2/6 “Security of Supply”. The normal standard of security applied in the design of distribution systems shall generally, therefore, be in accordance with the latest revision of ER P2/6. This code of practice contributes to the facilitation of design assessments made under ER P2/6 criteria by defining the ratings to be assigned to overhead line circuits (or parts of).

3.1.2.3. Distribution Code Each Distribution Licence holder is required to hold, maintain and comply with a Distribution Code. Northern Powergrid does this by adopting the GB Distribution Code. The code covers all material technical aspects relating to connections to, and the operation and use of, the Distribution Systems of the Distribution Network Operators (DNOs).

The Distribution Code gives force to specific Engineering Recommendations. The one particularly relevant to this code of practice, in terms of defining our obligations is ER P2/6. As with the obligations under the Distribution Licences, this code of practice contributes to the facilitation of design assessments made under ER P2/6 criteria by defining the ratings to be assigned to overhead line circuits (or parts of).

3.2. Key Requirements The key requirements of this code of practice are to:

Harmonise Northern Powergrid overhead line rating legacy policies; and

Provide guidance on the overhead line ratings to be adopted (in Amps and MVA) for all new and existing overhead lines to ensure they are correctly applied to the distribution system.

3.3. Overhead Line Ratings The overhead line current ratings in this code of practice are based on guidance given in the following documents:

Engineering Recommendation P27, “Current Rating Guide for High Voltage Overhead Lines Operating in the UK Distribution System”; and

British Electricity Board’s ACE Report No. 104 (1986), “Report on the Derivation of Overhead Line Ratings Applicable to High Voltage Distribution Systems”.

The ratings given in ACE Report No. 104 are based on the recommendations given in the Central Electricity Generating Board’s (CEGB’s) Central Electricity Research Laboratory (CERL) Report RD/L/N 129/79, "A Statistical Approach to the Thermal Rating of Zebra Conductor Based on Real Weather Observations".

CERL report RD/L/N 129/79 details measurements taken on overhead line conductor operating in varying environments, taking into account the temperature effects on a continuously loaded conductor by the interaction of sun, wind and ambient temperature.

3.3.1. Guidance on the Selection of Overhead Line Conductor Rating

3.3.1.1. Percentage Excursion Time The CERL report RD/L/N 129/79 describes an approach that can be applied to a range of conductors, providing statistically based ratings related to predicted ‘percentage excursion times’ in conductor design temperature.

A ‘percentage excursion time’ is defined as:




“The percentage of time in any particular season (with an assumed mix of ambient conditions) that a continuously loaded conductor may exceed the line design maximum temperature”.

The concept of ‘percentage excursion time’ is a significant factor in the application of rating. Excursions can occur on occasions throughout the year when wind speed is low and air temperature or solar radiation is high. Excursion has been applied to distribution ratings, taking into account additional probabilities associated with load cycle and circuit fault rate, when the conductor is operating as a component in a distribution system to a prescribed network design.

The recommended ratings in this code of practice relate to the distribution system and various types of load cycle, and have as a basis a statistically low level of risk and extent of temperature excursion above conductor design temperature.

3.3.1.2. Weather Conditions The ratings in this document are based upon ambient conditions found typically in the United Kingdom. The weather conditions used as a basis for deriving excursion ratings assumed in this document are as follows:

Wind Speed: 0.5 m/s

Ambient Temperature (for each season):

Winter (Dec, Jan, Feb) 2 degrees Centigrade

Spring / Autumn (March, April / Sept, Oct, Nov) 9 degrees Centigrade

Summer (May, June, July, Aug) 20 degrees Centigrade

Solar Radiation: nil

3.3.1.3. Modes of Operation The circuit ratings applicable to the Northern Powergrid (Northeast) Limited and Northern Powergrid (Yorkshire) plc distribution system in various modes of operation are categorised as one of the following:

Single circuit radial systems,

Secondary distribution (ring) systems,

Multi-circuit primary supply systems; and

132kV systems.

3.3.1.4. Single Circuit Radial and Secondary Distribution (Ring) Systems Single circuit radial systems and secondary distribution (ring) systems have been assumed to be required to be capable of supplying maximum load (continuous or cyclic) with negligible temperature excursion, due to the likelihood of an outage occurring at any time in the year and persisting for some time without realistic potential for reducing load. An excursion of 0% shall therefore been adopted for these ratings. When consideration is given to single circuit radial systems, this type of system includes 11kV ‘rings’ operated with an open point, i.e. configured as a radial feeder.

3.3.1.5. Multi-Circuit Primary Supply Systems The shape of the load duration curve is a significant factor in the rating assessment for multi-circuit primary supply systems. These systems have been assumed to supply maximum load only in the event of a circuit outage. This arrangement is most commonly used for primary distribution, such as duplicate transformer feeders at 132kV and 33kV, but may also apply to an untapped secondary system voltage, e.g. 11kV circuits providing a firm supply to an end load. Multi-circuit systems include 33kV and 66kV rings that are normally operated closed.




A low risk of circuit outage at a time of peak load and the unlikely occurrence of excess temperature has been assumed for this type of system. An excursion of 3% shall therefore been adopted for these ratings.

For intensive industrial or commercial / city centre networks a 0.96 de-rating shall be applied to the 3% excursion rating (effectively returning to a zero risk of excursion). This de-rating factor is to be applied due to the higher risk of fault at peak load.

3.3.1.6. 132kV Systems The percentage excursion time in this code of practice applicable to 132kV systems is taken from ER P27. This standard adopts an excursion of 3% which shall generally be applied to 132kV overhead line circuits.

Selection of an alternative, albeit appropriate, percentage excursion time and the corresponding ratings shall ultimately depend upon the planning and design considerations of the network to which it is applied. Percentage excursion times above 3% shall only be considered on an individual circuit basis. In this case, a risk assessment shall be carried out, that includes a line survey to confirm design clearances, to demonstrate that it is ‘likely’ design temperature will not be exceeded and hence the risk of a statutory clearance infringement is nil.

Historically, an excursion of 10% has been adopted for specific circuits in line with legacy CEGB standard 993102, TPS 1/96 (Overhead Lines). This value assumes that following a fault, normal circuit loading can be restored within a relatively short period, well within twenty four hours, so that it remains ‘likely’ the design temperature will not be exceeded. For 132kV overhead lines in the distribution mode of operation, consideration shall be given to the duration of post fault circuit loading conditions when selecting an appropriate excursion value. The preparation of load management plans shall be required to off load circuits to a 0% excursion rating as far as is reasonably practicable within 24 hours of a fault occurring.

3.3.2. Limiting Factors for the Applied Rating A number of limiting factors exist that influence the choice of overhead line conductor rating to be applied. The assignment of ratings to any particular overhead line circuit (or part of) is ultimately based on the thermal limitations imposed by the overhead line conductor and the overhead line design specification. However, there are other practical restrictions that will limit the rating that can be applied.

Therefore the selection of line rating shall ultimately be in accordance with the maximum permissible conductor operating temperature (thermal rating), taking into account the principal limitations discussed in this section.

3.3.2.1. Thermal Limitations and Overhead Line Design Specifications The rating of an overhead line circuit is influenced by the thermal limitations (maximum design temperature) of the conductor. The maximum conductor design temperature is dependent on the type of conductor and line design specification. The effect on conductor sag shall also be considered to ensure statutory clearances are maintained.

Overhead lines are typically designed to give minimum statutory ground clearances at a maximum conductor design temperature of 50

OC, 65

OC or 75

OC.

3.3.2.2. Historical Overhead Line Design Specifications Historical overhead line specifications were based upon the requirements of the former overhead line regulations:

El.C.53 (1947 Revise) - Electricity (Supply) Acts, 1882 to 1936; and

The Electricity (Overhead Lines) Regulations 1970.




These regulations provided a basis for design as regards minimum ground clearance at a ‘likely’ maximum conductor design temperature. The ‘likely’ maximum conductor design temperature adopted in Northern Powergrid historical specifications was 122

OF (equating to 50

OC).

The following table shows the historical Northern Powergrid overhead line design specifications that are still in use on the distribution system. The table shall be used as a guide to determine what design temperature shall be assumed to be applied when deciding what thermal rating to adopt for a particular circuit (or part of) for a prescribed design specification.

The information contained within the table shall be used as a guide only and is independent of the type of conductor used. If in any doubt of what rating to apply, a ground profile / line survey shall be carried out in conjunction with obtaining conductor samples to determine what limiting factors may exist without infringement of minimum statutory ground clearances.

Voltage Distributor Design Specification Construction Period Design Temp to

be assumed

132kV * Northern/ Yorkshire

Tower lines (various constructions) – previous CEGB ownership

1930 – 1975 50OC

132kV * Northern/ Yorkshire

Tower lines (various constructions) – previous CEGB ownership

1975 – Present 75OC

66/132kV Northern NSP/004/046 (OHL9) (AP1 Style wood Pole lines)

2000- 2005 75°C

33/66kV Northern/ Yorkshire

Tower & Riley & Neate Mast lines (various constructions)

1930 – 1980 50OC

33/66kV Yorkshire Woodhouse Steel Masts Circa 1930/40 50°C

66kV Northern Merz & Mclelland “A” and Portal Lines 1930 – 1975 50OC

66kV Northern OHL4/85 Single & Portal Lines 1985 – 2000 75OC

33kV Northern/ Yorkshire

EATS 43-20 (heavy construction) 1968 – 1989 50°C

33kV Northern EATS 43-40 (at 33kV only) 1989 – Present 75OC

33kV Yorkshire EATS 43-40 (at 33kV only) 1989 – 2005 65OC

33/66kV Yorkshire CE/C/13 (heavy construction) Circa 1940/50/60s 50OC

33/66kV Yorkshire CE/C/20 Circa 1940/50/60s 50OC



33/66kV Yorkshire CE/C/36 (heavy construction) Circa 1940/50/60s 50OC

33/66kV Yorkshire CE/C/37 (heavy construction) Circa 1970s – 2002 65OC


HV Northern/ Yorkshire

BS1320 (light construction) 1953 – 1989 50OC


EATS 43-10 (light construction) 1968 – 1989 50OC


EATS 43-20 (heavy construction) 1968 – 1989 50OC

HV Northern Std Wishbone (light construction) 1930 – 1939 50OC

HV Northern Std Wishbone (heavy construction) 1930 – 1968 50OC




Voltage Distributor Design Specification Construction Period Design Temp to

be assumed

HV Northern NESCo Oak (light construction) 1939 – 1953 50OC

HV Yorkshire CE/C/18 (tipped triangle) 1930 – 1953 50OC

HV Yorkshire CE/C/31 (heavy construction) 1930 – 1989 50OC

HV** Northern EATS 43-40 (light construction) – 11/20kV

EATS 43-40 (heavy construction) – 11/20kV 1989 - present

50°C

75°C

HV** Yorkshire EATS 43-40 (light construction) – 11kV

EATS 43-40 (heavy construction) – 11kV 1989 – 2005

50°C

65OC

33/66kV Yorkshire CE/OM/DC1(M) Circa 1940/50/60s 65°C

33/66kV Yorkshire CE/C/37(M1) 1998 – present 75°C

Notes

* Note: CEGB 132kV tower lines were originally designed and constructed for a maximum operating temperature of 50OC until

circa 1975. From this point onwards new lines were generally designed and constructed to provide a maximum operating temperature of 75

OC. Additionally when existing 66/132kV tower lines are planned for refurbishment, the opportunity has been

taken to explore the potential for uprating the thermal rating of these lines to provide an increase in maximum operating temperature. In many cases a combination of conductor change, and the replacement of the insulator fittings can offer the opportunity of a 65 or 75°C line rating. However unless records show an increased rating has been achieved, then the line shall continue to be considered as having its original default 50°C design line rating.

For definitions of light and heavy construction terms detailed above, see clause 5.0

3.3.2.3. New Build Overhead Line Design Specifications The following table shows the current list of new build Northern Powergrid overhead line design specifications. It does not depict the overhead line design standards that shall be utilised for new build or refurbishment of overhead lines in Northern Powergrid.

The table shall only be used as a guide to determine what design temperature shall be applied when deciding what thermal rating to adopt for a particular circuit (or part of) for a prescribed design specification.

Further guidance can be sought from the Policy and Standards Manager.

The information contained within the table shall be used as a guide only. If in any doubt of what rating to apply, a ground profile / line survey shall be carried out in conjunction with obtaining conductor samples to determine what limiting factors may exist without infringement of minimum statutory clearances.

Voltage Distributor Design Specification Conductor(s) Design Temp

132kV Northern Powergrid

NSP/004/030 covering L4(M) and L7(C) tower lines – including design variations (e.g. L4(M)/1)

Various 175mm2 ACSR or 200mm2 AAAC or

300mm2 AAAC

75OC

66kV Northern Powergrid

NSP/004/030 covering L4(M) and L4(M66) tower lines – including design variations

175mm2 ACSR or 200mm2 AAAC typical

75OC

33/66/132kV Northern Powergrid

NSP/004/045 or NSP/004/046 (OHL 9/10 ) Single & Rutter wood pole designs used for construction of new 66/132KV lines and the replacement of Woodhouse mast and legacy 66kV lines.

175 mm 2AAAC or 200 mm2 AAAC

75OC

33/66kV Northern OHL4/85 (Portal Construction) 175 - mm2 AAAC 75OC




Voltage Distributor Design Specification Conductor(s) Design Temp

33/66kV Yorkshire CE/C/37(M1) (Portal Construction) 200 mm2 AAAC 75OC

HV up to and inc 20kV

Northern Powergrid

NSP/004/042 - (ENATS 43-40) - Bare wire 50 mm2 AAAC 50OC


Northern Powergrid NSP/004/042 - (ENATS 43-40) - Bare Wire 100, 175 or 200 mm2 AAAC 75OC


Northern Powergrid

NSP/004/042 - (ENATS 43-40) - Bare Wire 100, 175 or 200 mm2 AAAC 75OC


Northern Powergrid

NSP/004/044 - (ENATS 43-122) 50 mm2

XLPE covered (AL3) 50OC


Northern Powergrid

NSP/004/044 - (ENATS 43-122) 120 or 185mm2 XLPE

covered (AL3) 75OC

LV Northern Powergrid

NSP/004/041 – (ENA TS 43-12) ABC 4 x 70mm2 or 4 x 120mm2

ABC 75OC

3.3.2.4. Conductor Type The maximum conductor design temperature is also dependent upon the type, age of manufacture and resultant design of the conductor. This primarily affects Aluminium Conductor Steel Reinforced (ACSR) conductor and the temperature at which the protective grease will run out of the conductor (known as the ‘drop point’). The grease should have a sufficiently high ‘drop point’ to withstand the temperatures which can occur under post fault conditions and at the rated design temperature.

Particular care should be taken when identifying the age and design of existing ACSR conductor when considering the rating to be applied to a specific overhead line circuit (or part of). Only conductors manufactured and installed after circa 1975 are capable of achieving a 75

OC rating due to the way in which the protective grease was applied to

the inner and outer aluminium strands.

If in any doubt of the age of conductor in order to select a rating value, the integrity of the grease for ACSR conductors shall be determined by taking physical samples for detailed inspection.

3.3.2.5. Conductor Fittings Type The stability of joints and conductor connections (compression joints and conductor fittings) can also be a limiting factor when determining the rating to adopt for a specific overhead line circuit (or part of). This is more prevalent in the unlikely event of a temperature excursion. There may be design weaknesses or deterioration of components that may be overstressed by the higher temperatures both pre and post fault.

As an example, ‘Tate and Noral’ designs utilised at 132kV are usually unsuitable for 65OC or 75

OC operation. If in any

doubt of the integrity of the joints and connections, they shall be inspected with an infra red camera to determine if any ‘hot joints’ are present. Where hot joints are found they shall be tested and remade in accordance with NSP/004/122 “Guidance on the Electrical Resistance Testing of O/H line joints and terminations”. An appropriate thermal rating can then be assigned to the circuit under consideration.




3.3.3. Overhead Line Ratings

3.3.3.1. 132kV Ratings (Amps) The following table shows the ratings to be applied to a 132kV overhead line circuit (or part of) in amps so as that it is ‘likely’ that design temperature is not exceeded and hence infringe statutory clearances.

The table details the types of conductor utilised at 132kV. 3% excursion ratings shall be adopted as shown in the table. Selection of an alternative percentage excursion time and the corresponding ratings shall ultimately depend upon the planning considerations of the network to which it is applied (see section 3.3.1.3.3).

132kV Conductor Rating (AMPS)

Material Type Size (sq mm) Code Design

Temp (OC) Excursion Summer

Autumn / Spring

Winter

ACSR Single 175 Lynx 50 3% 432 501 539

ACSR Single 175 Lynx 65 3% 523 578 609

ACSR Single 175 Lynx 75 3% 574 623 651

ACSR Twin 175 Lynx 50 3% 865 1002 1077

ACSR Twin 175 Lynx 65 3% 1046 1156 1219

ACSR Twin 175 Lynx 75 3% 1148 1245 1302

ACSR 400 Zebra 50 3% 745 861 925

ACSR 400 Zebra 65 3% 902 994 1047

ACSR 400 Zebra 75 3% 990 1072 1119

AAAC 200 Poplar 50 3% 468 542 584

AAAC 200 Poplar 65 3% 568 628 662

AAAC 200 Poplar 75 3% 624 678 708

AAAC 300 Upas 50 3% 618 715 769

AAAC 300 Upas 65 3% 750 829 873

AAAC 300 Upas 75 3% 825 895 935

AAAC 500 Rubus 50 3% 849 982 1056

AAAC 500 Rubus 65 3% 1032 1139 1200

AAAC 500 Rubus 75 3% 1136 1231 1286

Notes: ACSR – Aluminium Conductor Steel Reinforced. AAAC – All Aluminium Alloy Conductor. Source data from ER P27 (except Upas data from EATL OHRAT v3.0 spreadsheet in line with ER P27 methodology). Twin 175 ACSR phase rating is assumed single conductor rating multiplied by no. of conductors in the bundle - no reduction is required due to thermal proximity of conductors within the bundle.




3.3.3.2. 132kV Ratings (MVA) The following table shows the ratings to be applied to a 132kV overhead line circuit (or part of) in MVA (at nominal design voltage).

The table details the types of conductor utilised at 132kV. 3% excursion ratings shall be adopted as shown in the table. Selection of an alternative percentage excursion time and the corresponding ratings shall ultimately depend upon the planning considerations of the network to which it is applied (see section 3.3.1.3.3).

132kV Conductor Rating (MVA)

Material Type Size (sq mm) Code Design

Temp (OC) Excursion Summer

Autumn / Spring

Winter

ACSR Single 175 Lynx 50 3% 99 114 123

ACSR Single 175 Lynx 65 3% 120 132 139

ACSR Single 175 Lynx 75 3% 131 142 149

ACSR Twin 175 Lynx 50 3% 198 229 246

ACSR Twin 175 Lynx 65 3% 239 264 279

ACSR Twin 175 Lynx 75 3% 262 285 298

ACSR 400 Zebra 50 3% 170 197 212

ACSR 400 Zebra 65 3% 206 227 239

ACSR 400 Zebra 75 3% 226 245 256

AAAC 200 Poplar 50 3% 107 124 133

AAAC 200 Poplar 65 3% 130 144 151

AAAC 200 Poplar 75 3% 143 155 162

AAAC 300 Upas 50 3% 141 164 176

AAAC 300 Upas 65 3% 172 189 200

AAAC 300 Upas 75 3% 189 205 214

AAAC 500 Rubus 50 3% 194 225 241

AAAC 500 Rubus 65 3% 236 260 274

AAAC 500 Rubus 75 3% 260 281 294





The table details the types of conductor utilised at 66kV. 0% or 3% excursion ratings shall be adopted as appropriate.

For 3% multi-circuit and primary supply systems, circuits in this mode of operation intended to supply intensive industrial or commercial centre loads, a de-rating factor of 0.96 shall be applied.

66kV Conductors Ratings (AMPS) - 0% Excursion Ratings (AMPS) - 3 % Excursion

Material Type Imperial (sq

inch) Metric (sq

mm) Code

Design Temp (OC)

Single Circuit and Secondary Distribution Systems Multi - circuit and Primary Supply Systems

Summer Spring/Autumn Winter Summer Spring/Autumn Winter

Copper 0.1 70 - 50 237 275 296 269 312 336

Copper 0.15 100 - 50 309 358 385 350 405 437

Copper 0.2 125 - 50 364 422 454 412 478 515

ACSR 0.1 100 Dog 50 253 290 311 284 327 351

ASCR 0.15 150 Dingo 50 338 391 421 382 443 476

ASCR 0.15 150 Wolf 50 346 401 431 392 454 488

ASCR 0.175 175 Lynx 50 382 442 476 433 501 539

ACSR 0.175 175 Lynx 65 462 510 538 523 578 609

ASCR 0.175 175 Lynx 75 507 550 575 574 623 651

ASCR 0.175 175 Caracal 50 373 432 464 422 489 526

ASCR 0.175 175 Caracal 65 451 498 525 510 564 595

AAAC - 100 Oak 50 260 301 324 294 341 367

AAAC - 100 Oak 65 314 348 367 356 394 415

AAAC - 100 Oak 75 345 375 392 391 424 444

AAAC - 175 Elm 50 378 438 472 428 496 534

AAAC - 175 Elm 65 459 507 535 520 574 606

AAAC - 175 Elm 75 504 547 572 571 620 648

AAAC - 200 Poplar 50 468 542 584

AAAC - 200 Poplar 65 568 628 662

AAAC - 200 Poplar 75 551 598 626 624 678 708




Notes: ACSR – Aluminium Conductor Steel Reinforced. AAAC – All Aluminium Alloy Conductor. Source data from ER P27, (except Elm and Poplar data from EATL OHRAT v3.0 spreadsheet in line with ER P27 methodology).




66kV Conductors Ratings (MVA) - 0% Excursion Ratings (MVA) - 3 % Excursion


inch) Metric (sq

mm) Code

Design Temp (OC)



Copper 0.1 70 - 50 27.1 31.4 33.8 30.8 35.7 38.4

Copper 0.15 100 - 50 35.3 40.9 44.0 40.0 46.3 50.0

Copper 0.2 125 - 50 41.6 48.2 51.9 47.1 54.6 58.9

ACSR 0.1 100 Dog 50 28.9 33.2 35.6 32.5 37.4 40.1

ASCR 0.15 150 Dingo 50 38.6 44.7 48.1 43.7 50.6 54.4

ASCR 0.15 150 Wolf 50 39.6 45.8 49.3 44.8 51.9 55.8

ASCR 0.175 175 Lynx 50 43.7 50.5 54.4 49.5 57.3 61.6

ACSR 0.175 175 Lynx 65 52.8 58.3 61.5 59.8 66.1 69.6

ACSR 0.175 175 Lynx 75 58.0 19.1 19.9 65.6 71.2 74.4

ASCR 0.175 175 Caracal 50 42.6 49.4 53.0 48.2 55.9 60.1

ASCR 0.175 175 Caracal 65 51.6 56.9 60.0 58.3 64.5 68.0

AAAC - 100 Oak 50 29.7 34.4 37.0 33.6 39.0 42.0

AAAC - 100 Oak 65 35.9 39.8 42.0 40.7 45.0 47.4

AAAC - 100 Oak 75 39.4 42.9 44.8 44.7 48.5 50.8

AAAC - 175 Elm 50 43.2 50.1 53.9 49.0 56.7 61.1

AAAC - 175 Elm 65 52.4 58.0 61.1 59.4 65.6 69.2

AAAC - 175 Elm 75 57.6 62.5 65.4 65.3 70.8 74.1






inch) Metric (sq

mm) Code

Design Temp (OC)



AAAC - 200 Poplar 50 53.5 62.0 66.7

AAAC - 200 Poplar 65 64.9 71.8 75.7

AAAC - 200 Poplar 75 62.9 68.3 71.5 71.4 77.5 81.0






inch) Metric (sq

mm) Code

Design Temp (OC)



Copper 0.1 70 - 50 237 275 296 269 312 336

Copper 0.15 100 - 50 309 358 385 350 405 437

Copper 0.2 125 - 50 364 422 454 412 478 515

ACSR 0.1 100 Dog 50 253 290 311 284 327 351

ASCR 0.15 150 Dingo 50 338 391 421 382 443 476

ASCR 0.15 150 Wolf 50 346 401 431 392 454 488

ASCR 0.175 175 Lynx 50 382 442 476 433 501 539

ACSR 0.175 175 Lynx 65 462 510 538 523 578 609

ACSR 0.175 175 Lynx 75 507 550 575 574 623 651

ASCR 0.175 175 Caracal 50 373 432 464 422 489 526

ASCR 0.175 175 Caracal 65 451 498 525 510 564 595

AAAC - 100 Oak 50 260 301 324 294 341 367






inch) Metric (sq

mm) Code

Design Temp (OC)



AAAC - 100 Oak 65 314 348 367 356 394 415

AAAC - 100 Oak 75 345 375 392 391 424 444

AAAC - 175 Elm 50 378 438 472 428 496 534

AAAC - 175 Elm 65 459 507 535 520 574 606

AAAC - 175 Elm 75 504 547 572 571 620 648

AAAC - 200 Poplar 50 468 542 584

AAAC - 200 Poplar 65 568 628 662

AAAC - 200 Poplar 75 551 598 626 624 678 708

Notes: ACSR – Aluminium Conductor Steel Reinforced. AAAC – All Aluminium Alloy Conductor. Source data from ER P27, (except Elm and Poplar data from EATL OHRAT v3.0 spreadsheet in line with ER P27 methodology).






inch) Metric (sq

mm) Code

Design Temp (OC)



Copper 0.1 70 - 50 13.5 15.7 16.9 15.4 17.8 19.2

Copper 0.15 100 - 50 17.7 20.5 22.0 20.0 23.1 25.0

Copper 0.2 125 - 50 20.8 24.1 25.9 23.5 27.3 29.4

ACSR 0.1 100 Dog 50 14.5 16.6 17.8 16.2 18.7 20.1

ASCR 0.15 150 Dingo 50 19.3 22.3 24.1 21.8 25.3 27.2






inch) Metric (sq

mm) Code

Design Temp (OC)



ASCR 0.15 150 Wolf 50 19.8 22.9 24.6 22.4 25.9 27.9

ASCR 0.175 175 Lynx 50 21.8 25.3 27.2 24.7 28.6 30.8

ACSR 0.175 175 Lynx 65 26.4 29.2 30.8 29.9 33.0 34.8

ACSR 0.175 175 Lynx 75 29.0 19.1 19.9 32.8 35.6 37.2

ASCR 0.175 175 Caracal 50 21.3 24.7 26.5 24.1 28.0 30.1

ASCR 0.175 175 Caracal 65 25.8 28.5 30.0 29.2 32.2 34.0

AAAC - 100 Oak 50 14.9 17.2 18.5 16.8 19.5 21.0

AAAC - 100 Oak 65 17.9 19.9 21.0 20.3 22.5 23.7

AAAC - 100 Oak 75 19.7 21.4 22.4 22.3 24.2 25.4

AAAC - 175 Elm 50 21.6 25.0 27.0 24.5 28.4 30.5

AAAC - 175 Elm 65 26.2 29.0 30.6 29.7 32.8 34.6

AAAC - 175 Elm 75 28.8 31.3 32.7 32.6 35.4 37.0

AAAC - 200 Poplar 50 26.8 31.0 33.4

AAAC - 200 Poplar 65 32.5 35.9 37.8

AAAC - 200 Poplar 75 31.4 34.1 35.7 35.7 38.7 40.5




3.3.3.7. HV (5.25kv to 20kV) Ratings (Amps) The following table shows the ratings to be applied to a HV overhead line circuit (or part of) in amps so as that it is ‘likely’ that design temperature is not exceeded and hence infringe statutory clearances.

The table details the types of conductor utilised at HV. 0% or 3% excursion ratings shall be adopted as appropriate.


HV Conductors Ratings (AMPS) - 0% Excursion Ratings (AMPS) - 3 % Excursion


inch) Metric (sq

mm) Code

Design Temp (OC)



Cadmium Copper 0.017 13 - 50 79 92 99

Cadmium Copper 0.025 - - 50 98 114 123

Cadmium Copper 0.04 - - 50 135 157 169

Copper 0.025 16 - 50 99 114 123

Copper 0.05 32 - 50 155 180 194

Copper 0.058 - - 50 167 193 208 189 219 236

Copper 0.075 - - 50 192 223 240 218 253 272

Copper 0.1 70 - 50 237 275 296 269 312 336

Copper 0.1 70 - 65 297 328 347 336 372 393

Copper 0.1 70 - 75 325 353 370 368 400 419

Copper 0.15 100 - 50 309 358 385 350 405 437

Copper 0.15 100 - 65 382 423 446 433 479 505

Copper 0.15 100 - 75 419 456 477 475 516 540

Copper 0.2 125 - 50 371 430 462 420 487 524

Copper 0.2 125 - 65 440 487 514 499 552 582

Copper 0.2 125 - 75 483 525 549 548 595 622

ASCR 0.05 50 Rabbit 50 158 183 198

ASCR 0.1 100 Dog 50 253 290 311 284 327 351

ASCR 0.1 100 Dog 65 302 332 350 340 377 398




HV Conductors Ratings (AMPS) - 0% Excursion Ratings (AMPS) - 3 % Excursion


inch) Metric (sq

mm) Code

Design Temp (OC)



ASCR 0.1 100 Dog 75 330 357 375 374 406 245

ASCR 0.15 150 Dingo 50 338 391 421 382 443 476

ASCR 0.15 150 Dingo 65 408 451 475 462 510 538

ASCR 0.15 150 Dingo 75 447 486 508 507 550 575

ASCR 0.15 150 Wolf 50 346 401 431 392 454 488

ASCR 0.15 150 Wolf 65 418 462 488 474 524 552

ASCR 0.15 150 Wolf 75 549 498 521 520 564 590

ASCR 0.175 175 Lynx 50 382 442 476 433 501 539

ACSR 0.175 175 Lynx 65 462 510 538 523 578 609

ACSR 0.175 175 Lynx 75 507 550 575 574 623 651

ASCR 0.175 175 Caracal 50 373 432 464 422 489 526

ASCR 0.175 175 Caracal 65 451 498 525 510 564 595

ASCR 0.175 175 Caracal 75 494 536 561 560 607 635

AAAC 0.05 50 Hazel 50 165 191 206

AAAC - 100 Oak 65 314 348 367 356 394 415

AAAC - 100 Oak 75 345 375 392 391 424 444

AAAC - 175 Elm 65 458.7 506.9 534.6 520 574 606

AAAC - 175 Elm 75 504.2 547.1 572.1 571 620 648

AAAC - 200 Poplar 65 568 628 662

AAAC - 200 Poplar 75 551 598 626 624 678 708

XLPE - CC (AL2) - 50 - 50 147 171 184 167 193 208

XLPE - CC (AL2) - 120 - 75 346 376 393 392 426 445

XLPE - CC (AL2) - 185 - 75 456 494 516 516 560 585

Notes: ACSR – Aluminium Conductor Steel Reinforced. AAAC – All Aluminium Alloy Conductor. XLPE CC - Crosslinked Polyethylene Covered Conductor.source data from ENA TS 43-122 Table 9 Source data from ER P27, (except Elm, Poplar, XLPE CC (AL2) and XLPE CC (AL3) data from EATL OHRAT v3.0 spreadsheet in line with ER P27 methodology).




3.3.3.8. 11kV Ratings (MVA) The following table shows the ratings to be applied to an 11kV overhead line circuit (or part of) in MVA (at nominal design voltage).





inch) Metric (sq

mm) Code

Design Temp (OC)



Cadmium Copper 0.017 13 - 50 1.5 1.8 1.9

Cadmium Copper 0.025 - - 50 1.9 2.2 2.3

Cadmium Copper 0.04 - - 50 2.6 3.0 3.2

Copper 0.025 16 - 50 1.9 2.2 2.3

Copper 0.05 32 - 50 3.0 3.4 3.7

Copper 0.058 - - 50 3.2 3.7 4.0 3.6 4.2 4.5

Copper 0.075 - - 50 3.7 4.2 4.6 4.2 4.8 5.2

Copper 0.1 70 - 50 4.5 5.2 5.6 5.1 5.9 6.4

Copper 0.1 70 - 65 5.7 6.2 6.6 6.4 7.1 7.5

Copper 0.1 70 - 75 6.2 6.7 7.0 7.0 7.6 8.0

Copper 0.15 100 - 50 5.9 6.8 7.3 6.7 7.7 8.3

Copper 0.15 100 - 65 7.3 8.1 8.5 8.2 9.1 9.6

Copper 0.15 100 - 75 8.0 8.7 9.1 9.0 9.8 10.3

Copper 0.2 125 - 50 7.1 8.2 8.8 8.0 9.3 10.0

Copper 0.2 125 - 65 8.4 9.3 9.8 9.5 10.5 11.1

Copper 0.2 125 - 75 9.2 10.0 10.5 10.4 11.3 11.9

ASCR 0.05 50 Rabbit 50 3.0 3.5 3.8

ASCR 0.1 100 Dog 50 4.8 5.5 5.9 5.4 6.2 6.7

ASCR 0.1 100 Dog 65 5.8 6.3 6.7 6.5 7.2 7.6

ASCR 0.1 100 Dog 75 6.3 6.8 7.1 7.1 7.7 4.7






inch) Metric (sq

mm) Code

Design Temp (OC)



ASCR 0.15 150 Dingo 50 6.4 7.4 8.0 7.3 8.4 9.1

ASCR 0.15 150 Dingo 65 7.8 8.6 9.0 8.8 9.7 10.3

ASCR 0.15 150 Dingo 75 8.5 9.3 9.7 9.7 10.5 11.0

ASCR 0.15 150 Wolf 50 6.6 7.6 8.2 7.5 8.6 9.3

ASCR 0.15 150 Wolf 65 8.0 8.8 9.3 9.0 10.0 10.5

ASCR 0.15 150 Wolf 75 10.5 9.5 9.9 9.9 10.7 11.2

ASCR 0.175 175 Lynx 50 7.3 8.4 9.1 8.2 9.5 10.3

ACSR 0.175 175 Lynx 65 8.8 9.7 10.3 10.0 11.0 11.6

ACSR 0.175 175 Lynx 75 9.7 10.5 11.0 10.9 11.9 12.4

ASCR 0.175 175 Caracal 50 7.1 8.2 8.8 8.0 9.3 10.0

ASCR 0.175 175 Caracal 65 8.6 9.5 10.0 9.7 10.7 11.3

ASCR 0.175 175 Caracal 75 9.4 10.2 10.7 10.7 11.6 12.1

AAAC - 50 Hazel 50 3.1 3.6 3.9

AAAC - 100 Oak 65 6.0 6.6 7.0 6.8 7.5 7.9

AAAC - 100 Oak 75 6.6 7.1 7.5 7.4 8.1 8.5

AAAC - 175 Elm 65 8.7 9.7 10.2 9.9 10.9 11.5

AAAC - 175 Elm 75 9.6 10.4 10.9 10.9 11.8 12.3

AAAC - 200 Poplar 65 10.8 12.0 12.6

AAAC - 200 Poplar 75 10.4 11.3 11.9 11.9 12.9 13.5

XLPE – CC (AL2) - 50 Covered

Conductor 50 2.8 3.2 3.5 3.2 3.7 4.0


Conductor 75 6.6 7.2 7.5 7.5 8.1 8.5


Conductor 75 8.7 9.5 9.9 9.9 10.7 11.2

Note: Combinations of conductor type and max operating temp that have never been constructed have been deleted from the tables to aid clarity eg 175mm AAAC @ 50°C









inch) Metric (sq

mm) Code

Design Temp (OC)



Cadmium Copper 0.017 13 - 50 2.7 3.2 3.4

Cadmium Copper 0.025 - - 50 3.4 3.9 4.3

Cadmium Copper 0.04 - - 50 4.7 5.4 5.9

Copper 0.025 16 - 50 3.4 3.9 4.3

Copper 0.05 32 - 50 5.4 6.2 6.7

Copper 0.058 - - 50 5.8 6.7 7.2 6.5 7.6 8.2

Copper 0.075 - - 50 6.7 7.7 8.3 7.6 8.8 9.4

Copper 0.1 70 - 50 8.2 9.5 10.3 9.3 10.8 11.6

Copper 0.1 70 - 65 10.3 11.4 12.0 11.6 12.9 13.6

Copper 0.1 70 - 75 11.3 12.2 12.8 12.7 13.9 14.5

Copper 0.15 100 - 50 10.7 12.4 13.3 12.1 14.0 15.1

Copper 0.15 100 - 65 13.2 14.7 15.4 15.0 16.6 17.5

Copper 0.15 100 - 75 14.5 15.8 16.5 16.5 17.9 18.7

Copper 0.2 125 - 50 12.9 14.9 16.0 14.5 16.9 18.2

Copper 0.2 125 - 65 15.2 16.9 17.8 17.3 19.1 20.2

Copper 0.2 125 - 75 16.7 18.2 19.0 19.0 20.6 21.5

ASCR 0.5 50 Rabbit 50 5.5 6.3 6.9

ASCR 0.1 100 Dog 50 8.8 10.0 10.8 9.8 11.3 12.2

ASCR 0.1 100 Dog 65 10.5 11.5 12.1 11.8 13.1 13.8

ASCR 0.1 100 Dog 75 11.4 12.4 13.0 13.0 14.1 8.5






inch) Metric (sq

mm) Code

Design Temp (OC)



ASCR 0.15 150 Dingo 50 11.7 13.5 14.6 13.2 15.3 16.5

ASCR 0.15 150 Dingo 65 14.1 15.6 16.5 16.0 17.7 18.6

ASCR 0.15 150 Dingo 75 15.5 16.8 17.6 17.6 19.1 19.9

ASCR 0.15 150 Wolf 50 12.0 13.9 14.9 13.6 15.7 16.9

ASCR 0.15 150 Wolf 65 14.5 16.0 16.9 16.4 18.2 19.1

ASCR 0.15 150 Wolf 75 19.0 17.3 18.0 18.0 19.5 20.4

ASCR 0.175 175 Lynx 50 13.2 15.3 16.5 15.0 17.4 18.7

ACSR 0.175 175 Lynx 65 16.0 17.7 18.6 18.1 20.0 21.1

ACSR 0.175 175 Lynx 75 17.6 19.1 19.9 19.9 21.6 22.6

ASCR 0.175 175 Caracal 50 12.9 15.0 16.1 14.6 16.9 18.2

ASCR 0.175 175 Caracal 65 15.6 17.3 18.2 17.7 19.5 20.6

ASCR 0.175 175 Caracal 75 17.1 18.6 19.4 19.4 21.0 22.0

AAAC - 50 Hazel 50 5.7 6.6 7.1

AAAC - 100 Oak 65 10.9 12.1 12.7 12.3 13.6 14.4

AAAC - 100 Oak 75 12.0 13.0 13.6 13.5 14.7 15.4

AAAC - 175 Elm 65 15.9 17.6 18.5 18.0 19.9 21.0

AAAC - 175 Elm 75 17.5 19.0 19.8 19.8 21.5 22.4

AAAC - 200 Poplar 65 19.7 21.7 22.9

AAAC - 200 Poplar 75 19.1 20.7 21.6 21.6 23.5 24.5


Conductor 50 5.1 5.9 6.3 5.7 6.7 7.2


Conductor 75 12.0 13.1 13.7 13.6 14.8 15.5


Conductor 75 15.8 17.2 18.0 17.9 19.5 20.4

Note: Combinations of conductor type and max operating temp that have never been constructed have been deleted from the tables to aid clarity eg 175mm AAAC @ 50°C




3.3.3.10. LV Ratings (Amps) The following table shows the ratings to be applied to LV overhead line circuits (or part of) in Amps (at nominal design voltage).

The table details the types of conductor utilised at LV.

LV Conductors Ratings (AMPS)

Material Type Imperial (sq inch)

Metric (sq mm)

Code Design Temp (OC)

Single Circuit Distribution Systems

Summer Spring/Autumn Winter

Open Wire Network - (4/5 wire) – Bare and PVC Insulated

Copper 0.05 32 - 50 155 180 194

Copper 0.1 70 - 50 237 275 296

Copper 0.15 100 - 50 309 358 385

Copper 0.2 125 - 50 371 430 462

AL 0.5 50 Ant 50 163 189 204

AL .1 100 Wasp 50 258 299 322

Aerial Bundled Conductors (ABC) Common Design Rating (Ambient Temp 25°C)

Pole Top Under - eaves

ABC (pole Top) - 2 x 35 - 75 138 116

ABC (pole Top) - 4 x 35 - 75 117 98

ABC (pole Top) - 4 x 50 - 75 143 120

ABC (pole Top) - 4 x 70 - 75 183 154

ABC (pole Top) - 4 x 95 - 75 228 191

ABC (pole Top) - 4 or 5 x 120 - 75 300 270

Notes: Copper – Source data from P27 AL – Aluminium Conductor (Plain Aluminium) – Source data from P27 ABC – Aerial Bundled Conductor – Source data ENA TS 43-13 Issue 2 – “Aerial Bundled Conductors (ABC) Insulated with Cross linked Polyethylene For Low Voltage Overhead Distribution”

Document reference IMP/001/011 Document Type Code of Practise



4. References

4.1. External Documentation Reference Title Version and date

El.C.53 Overhead Line Regulations - made by the Electricity (Supply) Acts, 1882 to 1936.

1947 Revise

Overhead Line Regulations 1970

The Electricity (Overhead Lines) Regulations 1970.

1970

ESQC Regulations The Electricity Supply, Quality and Continuity Regulations 2002.

No. 2665, 2002

ER P27 Engineering Recommendation P27, “Current Rating Guide for High Voltage Overhead Lines Operating in the UK Distribution System”.

November 1986

ER P2/6 Engineering Recommendation P2/5 “Security of Supply”. July 2006

BEB ACE report No.104

British Electricity Board’s ACE Report No. 104 (1986), “Report on the Derivation of Overhead Line Ratings Applicable to High Voltage Distribution Systems”.

No.104, 1986

CEGB TPS 1/96 Central Electricity Generating Board’s (CEGB) standard 993102, TPS 1/96, “Current Ratings for Overhead Line Conductors”.

993102, Issue 9, August 1984

CERL Report RD/L/N 129/79

CEGB Central Electricity Research Laboratory Report RD/L/N 129/79, "A Statistical Approach to the Thermal Rating of Zebra Conductor Based on Real Weather Observations".

CERL Report RD/L/N 29/76

CEGB Central Electricity Research Laboratory Report RD/L/N 29/76, "The Evaluation of Continuous and Overload ratings for Overhead Lines".

March 1977

ENATS 43-8 Electricity Networks Association Technical Specification 43-8, “Overhead Line Clearances”.

4.2. Internal Documentation

Reference Title Version and date

None

NSP/004/011 Code of Practise on Overhead Line Clearances

NSP/004/041 Code of Practise for LV ABC Overhead Lines

NSP/004/042 Code of Practise for HV Wood Pole Lines up to and including 33kV

NSP/004/044 Code of Practise for Compact Covered Construction on Wood Pole Lines up to and including 33kV




NSP/004/030 Code of Practise for the Construction and Refurbishment of Steel Tower Lines

NSP/004/122 Guidance on the Electrical Resistance Testing oh Overhead Line Joints and Terminations

4.3. Summary of Amendments

Clause Summary of Amendments

General Complete document has been reformatted into modern CDS document format

1.0 Purpose References to Legacy companies removed and history of superseded documents inserted into this clause

2.0 Scope The scope of this document has been extended to cover LV Network ratings and the reference to ENA TS 43-8 for clearances have been updated to NSP/004/011

2.1 Table of Contents New Section providing a table of contents has been added

3.3.2.2 Historical Overhead Line design Specifications

This section has been amended to better reflect the range of historical designs that exist on the network together with their default maximum operating temperatures

3.3.2.3 New Build Overhead Line design Specifications

This section has been amended to reflect the range of new build specifications available together with their default maximum operating temperatures

3.3.3 Overhead Line Ratings

This section and its associated sub-clauses have been edited to remove conductors or operating conditions never installed on the Northern Powergrid network, together with the addition of new conductors including a new section covering LV Network ratings

4.2 Summary of Amendments

All references to internal documentation have been updated

5.0 Definitions The terms Light construction and Heavy Construction and their relationship with conductor sizes have been added to the definitions section

6.0 Authority for Issue Amended Authority for Issue sign off sheet

5.0 Definitions

Term Definition

HV High Voltage

LV Low Voltage

EHV Extra High Voltage

DNO Distribution Network Operator

ESQCR Electricity Supply, Quality and Continuity Regulations 2002

CEGB Central Electricity Generating Board

CERL Central Electricity Research Laboratory

BEB British Electricity Board

ER Engineering Recommendation

EATS Electricity Association Technical Specification (now ENATS)




ENATS Energy Networks Association Technical Specification (formally EATS)

CE/C/ Chief Engineer/Construction

BS British Standard

ACSR Aluminium Conductor Steel reinforced

AAAC All Aluminium Alloy Conductor

XLPE Crosslinked Polyethylene

CC Covered Conductor OC Degrees Centigrade

OF Degrees Fahrenheit

Light Construction This term refers to lines with conductor cross sectional areas of <=32mm2

HDBC or 50mm2 AAAC or their imperial equivalents

Heavy Construction This term refers to lines with conductor cross sectional areas of >=70mm2

HDBC or 100mm2 AAAC/ACSR or their imperial equivalents




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 15/09/15

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

Yes Period: Reason:

Sign Date

G Hammel Senior Policy and Standards Engineer

Ged Hammel 16/09/15

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

M Walbank System Planning Manager Mick Walbank 15/09/15

6.4. Authorisation

Authorisation is granted for publication of this document.

Sign Date

M Nicholson Head of Asset Management Mark Nicholson 16/09/15

IMP/001/011 Code of Practice for Guidance on the … - August 1987 NEEB Engineering Instruction ER...

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