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The Energy Networks Association (ENA) represents the interests of all energy companies in the UK. The Document Catalogue System is an online catalogue of engineering documents available from the ENA.
Documents available from the site include Technical Specifications, Engineering Recommendations and Reports, BEBS Specifications and reports supporting the electricity network process and policies.
Most documents are available to anybody but a small number are confidential to ENA member companies and can only be accessed by those member companies. The system allows clients that are not full ENA members to purchase documents by credit/debit card via secure transactions provided by WorldPay.
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WARNING! Some of the older (pre 2003) documents available on this site were originally published by the now defunct Electricity Association. Please note that the ENA cannot take responsibility for the condition and content of these older documents and you are advised to seek advice before acting upon information held in them.
Distributed Generation Connection Guide: G98 & G99
Low voltage heat-shrinkable material components for use up to and including 600/1 000 V
Emergency rated system transformers 66/20.5 kV, 66/11.5 kV and 33/11.5 kV delta/star and star/star connected
Low voltage overhead line shrouding materials
Aerial Bundled Conductors Insulated with Cross-Linked Polyethylene for Low Voltage Overhead Distribution
Fault Passage Indicators up to 132kV for Underground and Overhead Distribution Systems
Operational procedure associated with electricity supplies for traction purposes on AC and DC electrified lines
Code of practice for the coordination of power line carrier system frequencies in the range 30•0 kHz to 526•5 kHz
Issue 3 - Amendment 8
Recommendations for the Connection of Generating Plant to the Distribution Systems of Licensed Distribution Network Operators
Recommendations for the safe working of utilities’ staff and other parties near light rapid transit systems
Issue 1 – Amendment 10
Requirements for the connection of generation equipment in parallel with public distribution networks on or after 27 April 2019
Technical Requirements for Customers’ Export and Import Limitation Schemes
Specification for single circuit overhead pole lines for use at high voltage up to and including 33 kV
Guidance on the application of Engineering Recommendation P2, Security of Supply
Security of Supply
Environmental classification and corrosion protection of structures, plant and equipment
Structural testing of wood poles prior to climbing or use as a personal support
Tests on power cables with XLPE insulation and metallic sheath and their accessories, for rated voltages of 66 kV (Um = 72.5 kV), 110 kV (Um 123 kV) and 132 kV (Um = 145 kV)
Guidance on Neutral Current Diversion
400 V a.c. switchgear, controlgear and fusegear assemblies
Public Electricity Network Distribution Assemblies
Outdoor, free standing CTs & VTs up to 36 kV
Design and use of temporary scaffold guards and conductor support systems
Insulated Aerial Bundled Conductors for Low Voltage Overhead Distribution Systems – Erection Requirements
Covered-conductors for overhead lines (having rated Voltages Uo/U greater than 0.6/1 kV up to and including 19/ 33 kV)
Stay strands and stay fittings for overhead lines
Earth rods and their connectors
Environmental test requirements for protection and control equipment and systems
Application of ancillary electrical equipment
Standard numbering for small wiring (for switchgear and transformers together with their associated relay panels)
Engineering Recommendation G100 Issue 2 Overview and Summary Guide
Requirements for the Application of Protective Multiple Earthing to Low Voltage Networks
National Equipment Defect Reporting Scheme (NEDeRS®) – Notes of guidance
Overhead line conductors - protection against corrosion by the application of anti-corrosion grease during manufacture
Insulating foam-filled tube and solid rod for live working
Guidance for the operation and management of fluid filled cables. This document replaces ETR 135.
Distribution cables of rated voltage 0.6/1/ (1.2) kV with XLPE insulation, concentric waveform copper wire and solid aluminium conductors
Guidelines for the Provision of Low Voltage Connections to Multiple Occupancy Buildings
Switchgear for use on 66 kV to 132 kV distribution systems Part 5 Inductive voltage transformers, capacitor voltage transformers, combined unit transformers and current transformers for use on 72.5 kV to 145 kV distribution systems
Switchgear for use on 66 kV to 132 kV distribution systems (Disconnectors and earthing switches)
Measures necessary to minimise corrosion damage to buried metallic structures by neighbouring cathodic protection installations
Power installations exceeding 1 kV a.c. – Design of high-voltage open-terminal stations
Aerial bundled conductors insulated with cross-linked polyethylene for low voltage overhead distribution
Specification for single circuit overhead lines of compact covered construction on wood poles for use at high voltage up to and including 33 kV
XLPE covered-conductors for overhead lines (having rated voltages Uo/U greater than 0.6/1 kV up to and including 19/33 kV)
Partial discharge testing of bushings, capacitors, instrument transformers and switchgear of rated voltage 7.2 - 420 kV inclusive
Single core cables for use in substations having extruded insulation and rated voltages of 6350/11 000 volts, and 19 000/33 000 volts
Type approval tests for mechanical connections to metallic sheaths of cables Addendu
Distribution transformers - Part 4 Pole mounted transformers
Fittings for covered conductors for overhead lines (having rated voltages U0/U greater than 0.6/1 kV up to and including 19/33 kV)
Portable earthing equipment for overhead lines and substations
Switchgear for service up to 36 kV (Cable and Overhead conductor connected)
Complexity of Distribution Circuits Operated at or above 22kV
Specification for single circuit overhead lines on wood poles for use at 132kV
Guide to the application of Engineering Recommendation G5/4 in the assessment of harmonic voltage distortion and connection of non-linear equipment to the electricity supply system in the U.K
Calculation of fault currents in three-phase AC power systems (Application Guide to Engineering Recommendation G74)
Analysis package for assessing the security contribution from distributed generation and electricity storage systems – Users’ guide
Analysis Package For Assessing Generation Security Capability - Users' Guide
Harmonic voltage distortion and the connection of harmonic sources and/or resonant plant to transmission systems and distribution networks in the United Kingdom
Amendment 7
Issue 2 Amendment 3 Recommendations for the Connection of Type Tested Small-scale Embedded Generators (Up to 16A per Phase) in Parallel with Low-Voltage Distribution Systems
Issue 1 Amendment 4 Requirements for the connection of generation equipment in parallel with public distribution networks on or after 27 April 2019
Voltage fluctuations and the connection of disturbing equipment to transmission systems and distribution networks in the United Kingdom
EREC G99/NI - Northern Ireland Only
Requirements for the connection of generation equipment in parallel with public distribution networks in Northern Ireland on or after 27 April 2019
Guidelines for the design, installation, testing and maintenance of main earthing systems in substations
A guide for assessing the rise of earth potential at electrical installations
Framework for new low voltage housing development installations - Part 1 Design and planning
Framework for new low voltage housing development installations - Part 2 Materials specification
Framework for new low voltage housing development installations - Part 3 Installation and records
Framework for new industrial and commercial underground connections - Part 4 Design and planning
Framework for new industrial and commercial underground connections - Part 5 Materials specification
Framework for new industrial and commercial underground connections - Part 6 Installation and records
Framework for contestable diversionary and reinforcement works not exceeding 33 kV - Part 7 Contestable diversionary and reinforcement works
This Specification covers the technical requirements for three-phase, oil-immersed, 66/20.5 kV, 66/11.5 kV and 33/11.5 kV, 50 Hz, emergency rated system transformers for use on systems having the 11.5 kV or 20.5 kV neutral earthed directly or through resistance or reactance at one or more points. The design shall be such that the ONAN rating of the transformer is, as a minimum, 50% of the continuous emergency rating (CER). The normal usage envisaged for these transformers is for two units operating in parallel. The life expectancy of the transformers shall be not less than 40 years, and the choice of components and accessories shall not limit the life expectancy. The CER rating of both units is identical, where one unit is capable of supplying the total maximum demand during an outage of the other unit. Under this emergency loading condition, the winding temperature and top oil temperature of the in-service unit will remain within upper limits specified in this document for an ambient temperature not exceeding +5 °C; this will result in accelerated loss of life but no permanent damage to the unit. The intention is that any loss of life that takes place during emergency loading conditions will be compensated by any extension of life that results when both transformers are in service sharing the load. CER transformers are distinct from continuous maximum rated (CMR) transformers, which are designed for continuous operation at their maximum rating with no loss of life. NOTE: it is understood that the 40-year life expectancy requirement applies when operation is within the limits of IEC 60076, oil is maintained in accordance with IEC 60422 and the transformer and its components are maintained in accordance with the manufacturer’s recommendations. It is acknowledged in Clause 3.1.1 that when operating at the Continuous Emergency Rating, loss of life will be accelerated and so reduce the overall life expectancy of the transformer, dependent on the extent of operation at the Continuous Emergency Rating.
Medium revision to update document to latest standards and to include the latest amendment to the Ecodesign Regulations.
Foreword: Reference to clauses in IEC 60076-1 removed: this standard is being updated. Clauses now align with draft of new BS EN 60076-1 but this may change before the standard is issued. Clause 2: Standards updated to latest revisions, changed to BS where appropriate. Unreferenced standards removed. Publication Commission Regulation 2019/1783 added to Other Publications. ENA TS 14-1 added to Other Publications. Clause 3. Definitions referred to BS EN 60076-1. Clause 5.1.4 moved to 5.6. Clauses 5.3, 5.5, 5.5, 5.7, 5.8 added in accordance with draft IEC 60076-1. Operating frequency and number of phases added to 5.9.2. Clauses 5.14 to 5.23 added in accordance with draft IEC 60076-1. Clause 6.6. Updated to include Commission Regulation 2019/1783 and reference to Tier 1 changed to Tier 2. Optional compliance with Tier 2 removed. Clause 9 removed – information now included in Clause 5. New clauses 10.9 and 10.16 added, other clauses modified to line up with draft IEC 60076-1. Clause 11.18, now clause 10.22. Sub-clauses re-ordered to put FRA test first, requirement add for FRA to be carried out as first test at site. Clauses 12 & 13 & 14.1 removed – information now included in Clause 5. New clause 11.2.1 for separate cooler bank arrangement. Table 6, NOTE 1, Clause number removed. Clause 15.1.1, now 12.1.1. Requirement added that portable ladders shall comply with ENA TS 14-1. Clause 15.3.1, now 12.3.1. Cable size standardised at 1000mm2 Al, in line with ENA TS 35-3. Clause 15.6.2, now 12.6.2. Requirement added that fans shall comply with BS EN 50216-12. Clause 15.6.4, now 12.6.4. Requirement added that winding temperature indicators shall comply with BS EN 50216-11. Clause 16, now 13: Clause number removed from reference to IEC 62271-1.
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