adwea wiring regulation

CONSULTATION VERSION 0.1

The Electricity Wiring

Regulations

Issued by:

The Regulation and Supervision Bureau for the Water and Electricity Sector in the

Emirate of Abu Dhabi www.rsb.gov.ae

November 2006 Consultation Version 0.1


The Electricity Wiring Regulations (2007) of 40

List of Revisions

Revision Number

Date Prepared by: Checked by: Issued to:

0.1 Dec 2005 T Khan L Hill

M Al Sattari

Distribution Code Review Panel

0.2 June 2006 T Khan Distribution Code Review Panel

0.3 Sept 2006 T Khan L Hill

G Lewin

0.4 Oct 2006 T Khan N Carter

Consultation v0.1 Nov 2006 T Khan L Hill Public Consultation



C o n t e n t s

1. Introduction.......................................................................................................... 5 1.1 Citation and Commencement ............................................................... 5 1.2 Purpose ................................................................................................ 5 1.3 Scope and Enforcement ....................................................................... 5

2. Definitions............................................................................................................ 7 2.1 Interpretation ........................................................................................ 7

3. General Requirements ...................................................................................... 13 3.1 Technical Standards, Materials and Workmanship ............................ 13 3.2 Licensed Contractors.......................................................................... 13 3.3 Requirements for Safety..................................................................... 13 3.4 Environmental Conditions................................................................... 15

4. Electricity Supply Parameters ........................................................................... 16 4.2 Declared Voltage and Frequency ....................................................... 16 4.3 Harmonics and Voltage Disturbances ................................................ 16 4.4 Prospective Fault Current................................................................... 16

5. Electricity Supply Intake .................................................................................... 17 5.1 Supply Intake Rooms ......................................................................... 17 5.2 The Customer Connection Point ........................................................ 17 5.3 Multiple Occupancy Premises ............................................................ 18 5.4 Metering Requirements ...................................................................... 18 5.5 Application for Supply and Load Estimates ........................................ 18

6. Protection .......................................................................................................... 19 6.1 General Principles .............................................................................. 19 6.2 Overload and Short Circuit Protection ................................................ 19 6.3 Electric Shock Protection.................................................................... 20 6.4 Earth Leakage Protective Devices ..................................................... 20 6.5 Isolation .............................................................................................. 21 6.6 Insulation ............................................................................................ 22

7. Earthing ............................................................................................................. 23 7.1 General Principles .............................................................................. 23 7.2 Systems of Earthing ........................................................................... 23 7.3 Earth Electrodes ................................................................................. 24 7.4 Earth Conductors................................................................................ 24 7.5 Exposed Metallic Parts ....................................................................... 25 7.6 Equipotential Bonding Conductors ..................................................... 26 7.7 Earth Loop Impedance ....................................................................... 26 7.8 Lightning Protection............................................................................ 27 7.9 Functional Earthing............................................................................. 27



8. Selection of Components and Installation Requirements.................................. 28 8.1 Socket Outlets and Plug Connectors.................................................. 28 8.2 Switches and Isolators........................................................................ 28 8.3 Lighting ............................................................................................... 29 8.4 Conduits and Trunking ....................................................................... 30 8.5 Cables and Final Circuits.................................................................... 30 8.6 Distribution Boards ............................................................................. 32 8.7 LV Switchboards................................................................................. 33

9. Inspection, Testing and Certification ................................................................. 34 9.1 Installation Certificates ....................................................................... 34 9.2 Routine Inspection and Testing .......................................................... 35

10. SELV - Separated Extra Low Voltage Systems ................................................ 36 10.1 Source of SELV Power....................................................................... 36

11. Power factor Correction..................................................................................... 37 11.1 General Requirements ....................................................................... 37 11.2 Specifications ..................................................................................... 37

12. Motors and Generators ..................................................................................... 39 12.1 Electric Motors and Starters ............................................................... 39 12.2 Standby Generators ........................................................................... 39

13. Special Locations .............................................................................................. 40 13.1 Outdoor Sites...................................................................................... 40 13.2 Street Lighting, Traffic Signals and Signboards ................................. 40

APPENDICES

Note: Numbering System of the Regulations

Chapters are numbered as integers (e.g. 1, 2, 3, etc) Regulations are numbered by one full stop between numbers (e.g. 1.1, 1.2 etc) Clauses are numbered by two full stops between numbers (e.g. 3.1.1)



1. INTRODUCTION

1.1 Citation and Commencement

1.1.1 These Regulations shall be cited as the Electricity Wiring Regulations 2007.

1.1.2 These Regulations shall come into force on 1 March 2007 [proposed].

1.1.3 These Regulations are issued by the Regulation and Supervision Bureau through the powers vested in it under Article 62 of Law No (2) of 1998 Concerning the Regulation of the Water and Electricity Sector in the Emirate of Abu Dhabi.

1.1.4 These Regulations supersede the following regulations: ADWEA Wiring Rules and Regulations (3rd Edition 2003) WED Regulations for Electrical Installation Works (1980) Earth Leakage Protection Regulations (2001)

1.2 Purpose

1.2.1 The purpose of these Regulations is to provide guidelines and technical standards that promote the installation of safe and efficient systems of wiring in buildings and other Premises. The Regulations are not intended to substitute detailed specifications for designers of Installations nor to serve as instruction for untrained persons.

1.3 Scope and Enforcement

1.3.1 These Regulations shall apply to all Distribution Companies, Customers, property Owners, Licensed Contractors, or any other persons involved in the installation, maintenance or operation of Electrical Installations in any Premises or other place where there is an electricity supply provided by a Distribution Company. Such locations include, but are not limited to, domestic premises, commercial premises, industrial premises, public buildings, parks, farms, temporary supplies (construction sites, wedding tents etc), outbuildings, caravans, street lighting and traffic signs.

1.3.2 The scope of these Regulations does not include the electricity distribution networks belonging to Distribution Companies, except such equipment that is required at the interface with Customers, as detailed in these Regulations. (Note: requirements governing Distribution Companies’ networks are covered under the Electricity Supply Regulations 2007, as well as other relevant Licences, codes and standards).

1.3.3 These Regulations shall apply to all new Electrical Installations (including extensions and modifications to existing Installations) which are constructed following the date of commencement above (clause 1.1.2).

1.3.4 For existing Electrical Installations constructed before the date of commencement, the clauses listed in appendix 2 shall not apply, or shall apply after 1 January 2010 or, if earlier, at the time of the next inspection or re-certification, as indicated in appendix 2.

1.3.5 These Regulations shall be enforced by the relevant Distribution Companies in the Emirate of Abu Dhabi in accordance with procedures which shall be published by the



Distribution Company and approved by the Bureau.

1.3.6 Compliance with these Regulations shall be assessed in accordance with specifications and guidelines contained within this document or other relevant technical standards (see regulation 3.1).

1.3.7 Failure to comply with these Regulations, or any part thereof, shall be deemed as contrary to the Law. Such failures will be addressed in accordance with the Law under Article 65(5) (notices served by the Bureau), Article 66 (failure to comply) and Article 135 (offences and fines). Action may be taken against any Distribution Company, Customer, Owner, Licensed Contractor or other person to which these Regulations apply.

1.3.8 Relaxation of any of the requirements of the Regulations shall be approved by the Bureau upon written request from any Distribution Company, Customer, property Owner, Licensed Contractor or other person.



2. DEFINITIONS

2.1 Interpretation

Words which have been given definitions under this section are used in the Regulations beginning with capital letters e.g. “all Earth Conductors within a Premises must ...”. Terms in common use have not been given definitions and normal dictionary definitions apply (e.g. circuit breaker, plug, conduit). Words and expressions other than those described in this section, which are defined in the Law shall have the meanings ascribed to them in the Law. Words using the singular or plural number also include the plural or singular number, respectively.

2.1.1 Appliance: an item of current using equipment

2.1.2 Arm’s Reach: a zone of accessibility to touch, extending from any point on a surface where a person may stand or move about, to the limits which such person may reach without assistance (i.e. without any tool or ladder etc). Such a distance may normally be taken as 2.5m height from the standing surface, and 1.25m horizontally from the standing position.

2.1.3 Bonding Conductor: see Equipotential Bonding Conductor

2.1.4 Bureau: the Regulation and Supervision Bureau for the Water and Electricity Sector in the Emirate of Abu Dhabi, as established under Law No (2) of 1998.

2.1.5 Cable Tray: a cable support consisting of a continuous base with raised edges and no covering. A cable tray is considered to be non-perforated where less than 30% of the material is removed from the base.

2.1.6 Cable Trunking: a manufactured enclosure for the protection of cables, normally of rectangular cross section, of which one side is removable or hinged.

2.1.7 Circuit: a set of phase and neutral conductors generally installed as a group to supply power to a location, and which originate from one Protective Device. The following are related definitions:

(a) Ring Circuit: a Circuit which is wired from a single Protective Device, being run thorough an area to be supplied (via appropriate socket outlets, connectors etc) and returning back to the same Protective Device, thus forming an electrically continuous loop;

(b) Radial Circuit: a Circuit which is wired in a ‘radial’ or ‘branch’ configuration, emanating from a Protective Device to the area to be supplied;

(c) Spur Circuit: a Circuit which is wired in a ‘radial’ or ‘branch’ configuration from any point on a Ring Circuit;

(d) Final Circuit: a term generally used to describe Circuits which supply current using equipment or Appliances (normally via socket outlets or other types of connectors). E.g. a Circuit connecting from a Main Distribution Board to a Sub Distribution Board would not be described as a Final Circuit.

2.1.8 Circuit Protective Conductor: see Earth Conductor



2.1.9 Class I Equipment: equipment which includes a means for connection of Exposed Metallic Parts of the equipment to the Earth Conductor, thus providing protection against electric shock in case of failure of the basic insulation of the equipment or other fault condition.

2.1.10 Class II Equipment: equipment which does not include a means for connection to an Earth Conductor, and which provides supplementary insulation in addition to the basic insulation of the equipment, such as a plastic outer enclosure (also know as Double Insulated equipment). Specifications for Class II Equipment are given in BS2754.

2.1.11 Class III Equipment: equipment in which protection against electric shock relies on supply at SELV and in which voltages higher than SELV are not generated in the equipment (see BS2754).

2.1.12 Competency Licence: a licence issued by a Distribution Company to a company assessed as competent for work on Electrical Installations.

2.1.13 Connected Load: the aggregate load of Appliances and other electrical equipment at a Premises, summated using the method described under regulation 5.5.

2.1.14 Consumer Unit: see Main Distribution Board

2.1.15 Customer: any person, corporate body, or company who has an agreement with a Distribution Company for the supply of electricity.

2.1.16 Customer Connection Point (CCP): the point which defines the boundary between the Customers Installation and that of the Distribution Company. This point will normally be at the incoming cable of the Main Distribution Board and before the main circuit breaker. In special cases an alternative definition of the Connection Point may be agreed between the Customer and the Distribution Company.

2.1.17 Direct Contact: the accidental or inadvertent contact with electricity by a person, through the phase or neutral conductors of an Installation or Appliance, leading to an electric shock.

2.1.18 Distribution Company: a company or body holding a Licence from the Bureau, pursuant to the Law.

2.1.19 Danger: risk of injury to persons or animals or risk of damage to property

2.1.20 Distribution Board: an assembly designed for housing isolation switches and Protective Devices and for connecting multiple cable Circuits, including their associated neutral and Earth Conductors. The following are related definitions:

(a) Main Distribution Board (MDB): the Distribution Board which, in general, accepts the main incoming LV supply from the Distribution Company or Customer’s transformer. The MDB may also be know as the ‘Consumer Unit’ where this is generally an integrated unit containing the main isolation device and Protective Devices, principally in domestic Installations. (b) Sub Distribution Board (SDB): any Distribution Board which is supplied from the Main Distribution Board in a premises and which is used to distribute wiring and Circuits within a designated area (e.g. one floor in a multi-storey building).



(c) Final Distribution Board (FDB): a Distribution Board which supplies Final Circuits

2.1.21 Double Insulated Equipment: see Class II Equipment.

2.1.22 Earth: the conductive mass of earth, whose electric potential (voltage) at any point is conventionally taken as zero. The following are related definitions:

(a) Customer Earthed system (TT): where the Customer provides a Main Earth Terminal for the Installation, which is connected to a sufficient number of local Earth Electrodes (referred to in BS7671 as a ‘TT’ system). (b) Distribution Company Earthed system (TN-S): where the Distribution Company provides a connection to the Customer’s Main Earth Terminal, using the distribution network Earthing system, generally via the armouring or metallic sheath of the main incoming supply cable (referred to in BS7671 as a TN-S system). (c) Earthing or Earthed: a general term used to describe the connection of metallic parts of an Electrical Installation or an Appliance to Earth. Note: the terms ‘Grounding’ or ‘Grounded’ are sometimes used outside of these Regulations to mean the same as the above. (d) Earth Conductor: the protective conductors used to connect the Exposed Metallic Parts of an Electrical Installation and associated Appliances to Earth, via a Main Earth Terminal to local Earth Electrodes or the Distribution Company Earth. This includes ‘circuit’ Earth Conductors and ‘main’ Earth Conductors. Outside of these Regulations these may also be known as the Circuit Protective Conductor (CPC) or Earth Continuity Conductor (ECC) or commonly known as the ‘earth wire’. (e) Earth Electrode: a conductor or group of conductors in intimate contact with Earth, providing an electrical connection to Earth, and normally having a known and measurable value of Earth Resistance. (May also be known outside of these Regulations as ‘Earth Rod’, or Grounding Rod’.) (f) Earth Resistance: the resistance (in Ohms) of any point on an Installation to Earth, being measured using an approved testing device and approved procedure. (g) Earth Fault Loop Impedance (Zs): the total impedance presented to an earth fault current, comprising the impedance of the following parts of an Installation (illustrated in appendix 15):

- the circuit Earth Conductor; - the Main Earth Terminal; - the main Earth Conductors connecting to Earth Electrodes or the Distribution

Company Earth; - the path of earth fault current through the general mass of Earth, or through the

earth sheath or armouring of the Distribution Company cable; - the neutral earth connection at the Distribution Company transformer; - the distribution transformer winding;



- the phase conductors of the circuit back to the point of fault. (h) Main Earth Terminal: the main connection point at which the nominal value of Earth Resistance for an installation is taken, and at which Earth Conductors from the Earth Electrodes will be connected. This will normally be at or close to the Customer Connection Point. Outside of these Regulations the Main Earth Terminal may also be known as the ‘main earth bar’. (h) Functional Earth: an Earth or Earthing system which is provided for special functions (such as reduction of radio frequency interference, noise filtering for computers etc) and which is separate from the main Earthing system of an Installation.

2.1.23 Earth Leakage Circuit Breaker (ELCB): a circuit breaker which is designed to open the phase and neutral conductors of a circuit upon detection of a leakage of current (above a specified value) through the Earth Conductor or through Extraneous Metallic Parts of an Installation.

2.1.24 Electrical Installation (abbrv: Installation): an Electrical Installation generally comprises any fixed or temporary cable, switchgear, transformer or other electrical equipment or apparatus within a Premises or other place where there is an electricity supply (including outdoor locations). Fixed or portable electrical Appliances are not considered part of the Electrical Installation, although these Regulations do include requirements for the connection of Appliances (e.g. plugs and sockets).

2.1.25 Equipotential Bonding: the connection of Extraneous Metallic Parts, materials or components within a Premises which are not part of the Electrical Installation (e.g. water pipes, steel beams etc), using a designated conductor or cable, such as to maintain these at substantially the same potential (voltage) in the event of passage of electrical fault current through such parts. This may also be known as ‘PME Bonding’, outside of these Regulations.

2.1.26 Equipotential Bonding Conductor: a designated conductor installed to serve the function of Equipotential Bonding in a Premises (may also be known as the ‘PME Conductor’, outside of these Regulations).

2.1.27 Exposed Metallic Part: a metallic part of an Installation or Appliance which can be touched by persons and which is not normally live but may become live due to a fault condition. Exposed Metallic Parts are normally required to be connected to Earth (see Regulation 7.5).

2.1.28 Extraneous Metallic Part: a metallic part, structure or any metalwork within a Premises which is not part of the electrical Installation and which is not designed to carry current, but which may become live due to a fault condition. Extraneous Metallic Parts are required to be connected to Earth using Equipotential Bonding Conductors where there is significant risk that they may become live due to a fault condition (see regulation 7.6).

2.1.29 Extra Low Voltage (ELV): see Voltage

2.1.30 Final Circuit: see Circuit

2.1.31 High Voltage: see Voltage

2.1.32 Indirect Contact: contact of a person with electricity through Exposed Metallic Parts of



an Installation or Appliance or through Extraneous Metallic Parts in a Premises which have become live during fault conditions.

2.1.33 Installation: see Electrical Installation

2.1.34 Installation Certificate: a certificate in the format indicated in these Regulations which is issued by a Licensed Contractor after completion of work on an Installation and provided to the Customer/Owner of the Premises.

2.1.35 Law: means Law No (2) of 1998 Concerning the Regulation of the Water and Electricity Sector in the Emirate of Abu Dhabi.

2.1.36 Licensed Contractor: a company which has been assessed by the Distribution Company as competent to work on Electrical Installations and issued a Competency Licence.

2.1.37 Low Voltage: see Voltage

2.1.38 Luminaire: equipment which is generally designed to house one or more electric lamps and which may include diffusers, fixtures, transformers and auxiliary Circuits but is taken to exclude the lamps themselves. Note: outside of these Regulations a Luminare may commonly be referred to as a ‘light fitting’.

2.1.39 Main Distribution Board: see Distribution Board

2.1.40 Owner: the legal owner of a building or property in which an Electrical Installation is installed and connected to a supply of electricity. Note: in some cases an Owner may also be a Customer.

2.1.41 Premises: any occupied or un-occupied building or enclosure or other place where there is an electricity supply. Such locations would include, but are not limited to, domestic premises, commercial premises, industrial premises, public buildings, parks, farms, temporary supplies (construction sites, wedding tents etc), outbuildings, caravans, street lighting and traffic signs.

2.1.42 Prospective Fault Current: the value of current that would flow due to a short circuit fault of negligible impedance between live phase conductors, or between phase conductors and earth. The maximum Prospective Fault Current for an installation is normally taken at the Customer Connection Point. Also known as ‘fault level’.

2.1.43 Protective Conductor: see Earth Conductor

2.1.44 Protective Device: a device installed at the start of a Circuit which will automatically disconnect the input of electricity in the event of a fault or overload occurring on that Circuit. Such devices include fuses, fuse links, miniature circuit breakers (MCB), moulded case circuit breakers (MCCB), earth leakage circuit breakers (ELCB), and residual current devices (RCD).

2.1.45 Radial Circuit: see Circuit

2.1.46 Residual Current Device (RCD): a Protective Device which is normally installed to automatically isolate the supply to a Circuit or Distribution Board when the algebraic sum of currents in the phase and neutral conductors reaches a preset value.

2.1.47 Ring Circuit: see Circuit



2.1.48 Sub Distribution Board: see Distribution Board

2.1.49 Supply Intake: a term used to describe the location or room housing the main cable and equipment provided by a Distribution Company to provision a supply of electricity to a Premises (includes the Customer Connection Point).

2.1.50 Spur Circuit: see Circuit.

2.1.51 Voltage: (a) High Voltage (HV): an a.c. voltage greater than Low Voltage and less than 36kV between phases or 21kV between any phase and earth. (b) Low Voltage (LV): an a.c. voltage below 1000V between phases, or below 600V between any phase and earth, or, a d.c. voltage below 1500V between phases, or below 900V between any phase and earth. (c) Extra Low Voltage (ELV): a voltage not exceeding 50V a.c. or 120V d.c. whether between phase conductors or between phase conductors and earth. (d) Separated Extra Low Voltage (SELV): an Extra Low Voltage system which is electrically separated from Earth in such a way that a single fault cannot give rise to the risk of electric shock.



3. GENERAL REQUIREMENTS

3.1 Technical Standards, Materials and Workmanship

3.1.1 These Regulations provide guidelines and technical standards which have been written to be consistent with the principles contained in BS7671:2001 (generally known as the IEE Wiring Regulations 16th Edition). For the avoidance of doubt, where any provision in these Regulations contradicts any provision in BS7671, the requirements, standards or specifications under these Regulations shall apply.

3.1.2 Where a provision or technical requirement is not covered by these Regulations, BS7671 may be used as a guideline or specification, with prior approval from the Distribution Company and the Bureau.

3.1.3 All materials used in Electrical Installations shall be of good quality and installed in a neat and orderly manner.

3.1.4 All materials and equipment shall comply with relevant international standards which will be mainly BS (British Standards) or IEC (International Electrotechnical Commission) standards as referenced in these Regulations. Other international standards may be used, in particular where none are specified in these Regulations, with the prior approval of the Distribution Company. A list of BS and IEC standards applying to the main types of equipment is given in appendix 3.

3.1.5 The Distribution Company must check for compliance against relevant standards of materials and equipment used in an Installation, prior to providing an electricity supply.

3.1.6 The Distribution Company may issue specifications and requirements in addition to these Regulations, which will be endorsed / approved by the Bureau, and provided to interested parties on request.

3.1.7 Reference should also be made to UAE or Gulf standards which may be issued from time to time by the Emirates Standardisation and Metrology Authority (ESMA).

3.2 Licensed Contractors

3.2.1 Work on Electrical Installations may only be carried out by Licensed Contractors who have been assessed and approved by the Distribution Company and issued a Competency Licence.

3.2.2 The process for approval of Licensed Contractors shall be established by the Distribution Company and approved by the Bureau.

3.2.3 A register of Licensed Contractors shall be kept up-to-date by the Distribution Company and provided on request to any person.

3.3 Requirements for Safety

3.3.1 The provisions of these Regulations require that Electrical Installations are constructed and maintained so as to ensure the safety of all persons, including those working on the Installation, those using electrical equipment, as well as members of the general public.



In addition to the provisions detailed under the relevant sections of these Regulations, the following general safety provisions shall apply:

3.3.2 All parts of an Electrical Installation shall be constructed, installed and maintained so as to prevent Danger.

3.3.3 All parts of an Electrical Installation shall be sufficiently sized and rated to safely carry out the function for which they are required.

3.3.4 All parts of an Electrical Installation shall be insulated appropriate to the function they serve, in consideration of the expected operating environment, so as to prevent Danger.

3.3.5 All Exposed Metallic Parts of an Installation must be Earthed via appropriate Earth Conductors as detailed under regulation 7.4.

3.3.6 All Extraneous Metallic Parts within a Premises must be Earthed via Equipotential Bonding Conductors as detailed under regulation 7.6.

3.3.7 All Electrical Installations shall be fitted with an Earth Leakage Circuit Breaker (ELCB), Residual Current Device (RCD), or similar Protective Device, at the source of supply and at other appropriate points, as detailed in chapter 6 of these Regulations.

3.3.8 All Electrical Installations shall be protected against damage due to excess current (caused by a fault or overload) by suitable Protective Devices such as fuses, circuit breakers or other devices as detailed under chapter 6 of these Regulations.

3.3.9 All Electrical Installations shall be provided with a means of isolating the electricity supply at suitable sections, subsections and Circuits, and at points where Appliances are used, as detailed under regulation 6.5.

3.3.10 All parts of an Electrical Installation shall be suitably located and protected against accidental or deliberate interference, as well as risk of damage from other services (e.g. water supply).

3.3.11 All Electrical Installations shall be inspected and tested at the time of first commissioning and at intervals thereafter to ensure ongoing safety, as detailed under chapter 9 of these Regulations.

3.3.12 All Electrical Installations shall be suitably labelled so as to give information on the basic operating parameters, the source of supply, location in relation to other Installations, and any precautions that must be taken. Individual Circuits must be identified by numbering at the source end and at appropriate intervals along the route. For non-domestic Installations, all accessories and fittings must be marked with Circuit numbers.

3.3.13 Where parts of an Installation are accessible or visible to the general public they must be labelled with a warning: “LIVE – 230/400 VOLTS – DANGER OF DEATH” or similar wording in prominent black letters on a yellow background. This warning must be written in English and Arabic (see example in appendix 21). However, parts of final circuits and other points of normal use may be excluded from this requirement.

3.3.14 Special or unusual situations may require additional measures to be taken in relation to clauses 3.3.2 to 3.3.12. Adverse weather conditions, locations near water, locations where there is a risk of fire, or locations where young children are nearby are examples of site specific factors which must be taken into account in the design and construction



of an Installation, and before a supply is provided by the Distribution Company.

3.3.15 No extension or alteration to an Electrical Installation may be made without prior notification to the Distribution Company and without approval, testing and certification as detailed in chapter 9. In addition, any proposed increase in the loading of the main incoming supply, above 10% of the existing loading, must be notified to the Distribution Company.

3.4 Environmental Conditions

3.4.1 All parts of an Electrical Installation shall be suitably designed, constructed and maintained so as to operate safely and within their designed function under the expected operating environment. The following environmental conditions may be used as a guide if no other special factors apply:

(a) Maximum ambient (air) temperatures:

Outdoor (un-shaded) 60 degrees Celsius Outdoor (shaded) 50 degrees Celsius Indoor (not air conditioned) 40 degrees Celsius Indoor (air conditioned) 30 degrees Celsius

(b) Maximum ground temperature(at 1 metre depth): 35 degrees Celsius

(c) Maximum humidity: 100%

(d) Soil resistivity: according to local conditions

(e) Weather: mainly sunny, occasional fog (causing condensation on outdoor equipment), and occasional sandstorms

(f) Air quality: frequently dusty and corrosive



4. ELECTRICITY SUPPLY PARAMETERS

4.1.1 The parameters for electricity supplies provided to Customers in the Emirate of Abu Dhabi are defined in the Electricity Supply Regulations 2007, issued by the Bureau. These are repeated below:

4.2 Declared Voltage and Frequency

4.2.1 The declared supply voltage provided to Customers connected at LV shall be 230V single phase or 400V three phase. Since this is a change to the previous supply voltage declared by Distribution Companies of 415/433V a guidance note is provided in appendix 4.

4.2.2 The permissible variation of the supply voltage shall be kept within +/- 10% of the declared supply voltage.

4.2.3 The declared supply frequency provided to Customers shall be 50Hz.

4.2.4 The permissible variation of supply frequency shall be +/- 0.1Hz.

4.2.5 For Customers supplied at voltages above LV the allowed variation of voltage and frequency shall be the same as in clauses 4.2.2 and 4.2.4 above.

4.3 Harmonics and Voltage Disturbances

4.3.1 Customers’ Installations, and the use of electrical equipment therein, must be designed to avoid the generation of disturbances in the electricity supply, such as voltage fluctuations, voltage dips, voltage unbalance and harmonics, which are of a magnitude that adversely affect other Customers,

4.3.2 The permitted limits of such disturbances are given in the Electricity Distribution Code, Annex 1. Customers will be required to install filters or other equipment to mitigate against such disturbances that are outside the permitted limits (as explained in the aforementioned document).

4.4 Prospective Fault Current

4.4.1 The maximum 3 phase Prospective Fault Current (fault level) for LV supplies shall be 46kA (1 second) at the LV busbar of the Distribution Company’s HV/LV substation, or 30kA (1 second) at a LV feeder pillar, or 25kA (1 second) at a LV service turret.

4.4.2 The maximum 3 phase Prospective Fault Current for HV supplies shall be 31.5kA (for 3 seconds) or such lower value as otherwise agreed between the Distribution Company and the Customer.



5. ELECTRICITY SUPPLY INTAKE

5.1 Supply Intake Rooms

5.1.1 The electricity Supply Intake must be positioned in a dedicated room or housing.

5.1.2 There will normally be only one electricity Supply Intake for any Premises, except in exceptional circumstances and with prior approval from the Distribution Company.

5.1.3 The Supply Intake must be positioned in an area which is readily accessible to Distribution Company staff and must be at or close to the outside perimeter of a Premises. Supply Intakes must not be positioned in an area controlled by one of the tenants in a multi-occupancy building.

5.1.4 Equipment at the electricity Supply Intake must be located in a safe and accessible position, and kept clear of hindrance at all times. The use of Supply Intake rooms as storage rooms for any tools equipment or other materials is prohibited.

5.1.5 The Supply Intake must not be located on the reverse side of a bathroom or kitchen wall, or below a bathroom or kitchen. The Supply Intake must not be located below any water services or pipes, such as mains water supply, storage tanks, air conditioning chillers, or other liquids or hazardous materials.

5.1.6 The Supply Intake room should be well ventilated, preferably without the need for forced air circulation. Where the use of air conditioning is required the requirement for fresh air circulation and avoiding condensation should be catered for.

5.1.7 Typical Installation layouts and sizes of the electricity Supply Intake are given in appendix 21.

5.1.8 For large Installations the Supply Intake may consist of one or more LV switchboards, the requirements for which are given in regulation 8.7.

5.1.9 For Customers receiving supply directly from a HV/LV substation there may be special requirements for the Supply Intake room, such as special access locks for Distribution Company staff. The requirements for the design and construction of distribution substations, transformer rooms or HV switchgear rooms which are on the premises of the Customer will be specified by the Distribution Company.

5.2 The Customer Connection Point

5.2.1 The Customer Connection Point, or ‘CCP’ (also known as the ‘point of supply’), is normally deemed to be at the incoming cable connection from the Distribution Company, most commonly at the Main Distribution Board and before the main circuit breaker. In special cases an alternative definition of the Customer Connection Point may be agreed between the Customer and the Distribution Company. Metering equipment may be connected through a current transformer (c.t.) at a position other than directly at the Customer Connection Point.

5.2.2 Equipment at the Customer Connection Point shall be locked or sealed by the Distribution Company to prevent deliberate or accidental interference. Such locks or seals will include those for metering equipment, current transformers etc.



5.2.3 The Customer Connection Point must always include a means of emergency isolation in the case of a fault or breakdown (e.g. main circuit breaker) which is readily accessible and clearly labelled so as to be easily operated by the Customer. Such methods of emergency isolation must be left unlocked at all times.

5.3 Multiple Occupancy Premises

5.3.1 Multiple occupancy premises will normally be supplied by rising and lateral (R&L) mains cabling or busbars which are connect directly to the Supply Intake from the Distribution Company. Rising and lateral cables/busbars will normally be owned and operated by the building Owner on behalf of all Customers in a Premises.

5.3.2 The electricity metering for individuals Customers for a R&L mains system will normally be at the points nearest each Customer, remote from the main Supply Intake.

5.4 Metering Requirements

5.4.1 The requirements for Customer metering are contained in the Customer Metering Regulations 2005, issued by the Bureau. Additional detailed requirements and procedures will be provided by the Distribution Company where required. Typical layouts for metering equipment are shown in appendix 21.

5.5 Application for Supply and Load Estimates

5.5.1 Any Customer requiring a new supply or alteration to an existing supply must make an application to the Distribution Company using the appropriate forms and procedure published by the Company.

5.5.2 The proposed design of the Installation must be approved by the Distribution Company before commencement of construction. Details of the proposed design should be submitted, together with appropriate calculations and should include wiring drawings in the standard format shown in appendix 20.

5.5.3 The Customer must provide an estimate of the expected maximum electricity demand and/or Connected Load at the premises. This must be calculated by the Customer’s appointed Licensed Contractor, design engineer or other qualified person using the guidelines given in appendix 5.



6. PROTECTION

6.1 General Principles

6.1.1 All Electrical Installations shall be designed, constructed and maintained to provide protection against the following:

Overload Short circuits (phase to phase or phase to earth) Electric shock (due to Direct or Indirect Contact with electricity)

6.1.2 Protection against conditions of overload and short circuit will normally be provided by MCBs or similar devices (see regulation 6.2 below).

6.1.3 Protection of persons against electric shock due to Direct or Indirect Contact must be provided by one of the methods detailed in regulation 6.3 below.

6.2 Overload and Short Circuit Protection

6.2.1 All Electrical Installations must be provided with devices that protect against overload and short circuits, located at suitable sections and Circuits so as to give effective isolation of such conditions.

6.2.2 The main circuit breaker at the Customer Connection Point must be of MCB or MCCB type and adequately rated for the maximum Prospective Fault Current. Fused cutouts must not be used except in special circumstances (e.g. street lighting supplies).

6.2.3 Circuits feeding from the Customer’s main Distribution Board must be individually protected against overload and short circuits by suitable devices. Replaceable or re-wireable fuse links are not permitted for this purpose.

6.2.4 The time-current performance characteristic of Protective Devices must conform to the relevant reference standards listed in appendix 3. The time-current performance curves for the most common MCCB types are shown in appendix 10.

6.2.5 To ensure protection against overload, circuit cables must be sized taking into account the time-current characteristic of the Protective Device e.g. the nominal rating of an MCB / MCCB should be less than the rating of the circuit for which overload protection is required.

6.2.6 Protective Devices at the Main Distribution Board must have a maximum Prospective Fault Current rating above that declared by the Distribution Company for the relevant Customer Connection Point.

6.2.7 Protective Devices downstream of the Main Distribution Board may have a reduced Prospective Fault Current rating, taking into account the ‘energy-let-through’ characteristic (I2t) of the upstream Protective Device (see appendix 10). Where appropriate, an allowance may also be made for the attenuation of Prospective Fault Current due to the circuit length / impedance.



6.3 Electric Shock Protection

Direct Contact

6.3.1 The risk of persons coming into Direct Contact with electricity by touching phase or neutral conductors must be mitigated against in one or more of the following ways:

(a) insulation of conductors (basic insulation);

(b) double insulation of conductors (Class II Appliances);

(c) secure enclosures, barriers or covers on all uninsulated parts (e.g. connection terminals, busbar sections etc);

(d) reduced voltage supply (SELV);

(e) isolated (unearthed) supply at LV (e.g. BS3535 shaver socket supply);

(f) limitation of contact time and current by use of a Residual Current Device (see regulation 6.4);

Indirect Contact

6.3.2 Indirect Contact with electricity can occur when a voltage rise appears on the earthing of an Installation due to the passage of earth fault current and whilst a person is in contact with either:

(a) an Exposed (earthed) Metallic Part of an Appliance;

(b) an Exposed (earthed) Metallic Part of an Installation;

(c) an Extraneous (earthed) Metallic Part in a Premise.

6.3.3 The risk of electric shock in the above situations is mitigated against by ensuring that the maximum voltage rise on the earthing system is limited to a safe value (see regulation 7.7), and that different parts of the earthing system are kept at substantially the same voltage (see clause 7.1.1).

6.4 Earth Leakage Protective Devices

6.4.1 The requirement for earth leakage protection for all occupied Premises is made compulsory in these Regulations.

6.4.2 Earth leakage protection is required primarily to protect against electric shock by limiting the time and magnitude of current that may pass through the body of a person to Earth.

6.4.3 In addition earth leakage devices provide protection against ‘high resistance’ earth faults that may persist in an installation if the fault current is too low to operate devices such as MCBs. Such faults may cause overheating of circuits or connections and lead to a fire.

6.4.4 Earth leakage devices must operate on the ‘residual current’ principle, whereby the device will trip if the vector sum of currents carried by the phase and neutral conductors is above a preset value. They must not rely on the earthing of an installation. The older design of voltage operated earth leakage devices (ELCB) is not permitted (see appendix 9).



6.4.5 It should be noted that earth leakage devices do not protect against electric shock between phase conductors or between phase and neutral.

6.4.6 All Electrical Installations within occupied Premises must be provided with overall earth leakage protection of nominal rating 100mA, and having a time-current performance characteristic complying with IEC-60898 or BS3871. This requires that the device must operate within 200 milliseconds at the nominal current rating and within 40 milliseconds at 5 times the nominal rating. It must not operate below 50% of the nominal rating (see appendix 9).

6.4.7 The nominal rating for earth leakage protection shall be 100mA for Circuits supplying fixed equipment (e.g. lighting, air conditioning) and 30mA for Circuits supplying socket outlets and all kitchen appliances (e.g. cooker, fridge, washing machine). In higher risk areas and applications such as under water lighting, swimming pools etc the nominal operating current of earth leakage protection must be 10mA. A full list of applications and nominal current ratings is provided appendix 14.

6.4.8 Electrical Installations within Premises which are not normally occupied and which could suffer from inadvertent or nuisance interruption of supply may be exempt from the provision of earth leakage protection, subject to written approval of the Distribution Company. Such Installations may include, street lighting, traffic signs, telecommunications stations, pumping stations etc.

6.4.9 However, notwithstanding clause 6.4.8, all Circuits from which portable appliances or other hand operated equipment could be used must be provided with earth leakage protection.

6.4.10 Notwithstanding clause 6.4.6 and clause 6.4.8, special Circuits within a Premises, where there would be significant detriment or danger from the tripping of the earth leakage protection, may be excluded from the zone of earth leakage protection or provided with ‘time delayed’ devices (i.e. where the operating time is higher than indicated under clause 6.4.6). Such instances may include Circuits supplying fire protection equipment or safety alarms (not security alarms). All such cases must be declared in the Installation Certificate for the site and approved by the Distribution Company.

6.4.11 An earth leakage alarm may be provided for Circuits which are excluded from the zone of earth leakage protection (e.g. an alarm that does not cause tripping of the circuit but gives an audible warning to appropriate persons in the Premises).

6.4.12 Installations with high earth leakage currents (e.g. special equipment, or industrial installations) may be provided with ‘time delayed’ earth leakage devices, or in special cases, devices with a higher nominal current rating, up to 500mA . These must be clearly stated on the Installation Certificate and agreed with the Distribution Company.

6.5 Isolation

6.5.1 All Electrical Installations must be provided with a means of safe isolation at the main Supply Intake, which must be lockable or otherwise provided with a means of preventing interference (e.g. by the removal of operating handles into the safe custody of a responsible person). Isolation for maintenance or other work may be provided by the Protective Device if it is lockable (except for HV equipment).



6.5.2 An Installation must be further sectionalised by means of isolation at each Circuit in order to provide ease of access for safe working. Isolation for maintenance or other work may be provided by the Protective Device if it is lockable (except for HV equipment).

6.5.3 Each socket outlet or other connection point to an Appliance or other electrical equipment must be provided with a switch as a means of isolation. Such switches should be provided with a neon indicator where it is desirable to have a visual indication of the presence or absence of power (e.g. fridge, fire alarm, gas or smoke alarm, water heater).

6.5.4 Emergency isolation switches (e.g. push button switch) must be provided for moving machinery which may require immediate manual disconnection form the supply in the case of an accident or other situation to avoid Danger. Such equipment may include large motors, ventilation equipment, industrial machinery etc. Emergency push switches must operate on all phases of the supply, must be clearly marked and must be located in an easily accessible position.

6.6 Insulation

6.6.1 All Electrical Installations must be sufficiently insulated to protect against electric shock from Direct Contact by persons.

6.6.2 Live conductors must never be accessible to any persons other than for the purpose of testing, using special equipment and procedures.

6.6.3 Uninsulated equipment may be used at voltages below 25V a.c. or 60V d.c. (see SELV systems under chapter 10).



7. EARTHING

7.1 General Principles

7.1.1 Earthing of Exposed Metallic Parts of an Installation and Appliances, as well as Extraneous Metallic Parts in a Premises is required to serve the following functions of safety:

(a) allow the passage of fault current in the event of a live conductor touching any metallic part of an Installation or Appliance or Extraneous Metallic Part;

(b) ensure that the voltage rise on metallic parts during the passage of fault current is kept at a safe value (i.e. less than 50V);

(c) ensure that persons cannot be in contact with any two metallic parts which are at a different potential during the passage of fault current;

(d) ensure that the magnitude of any fault current is sufficient to operate overcurrent protective devices within a maximum safe time of 0.4 seconds;

(e) ensure that a ‘high resistance’ fault to Earth does not persist so as to cause overheating or fire and is cleared by earth leakage protection devices.

The necessary requirements to achieve these functions of safety are detailed in the following sections. Guidance notes on the principles of earthing are given for reference in appendices 6 to 9.

7.2 Systems of Earthing

7.2.1 Customers shall be provided with a supply operating under either of the following earthing systems:

(a) Customer Earthed (TT): the Customer provides a Main Earth Terminal for the Installation, which is connected to a sufficient number of local Earth Electrodes (referred to in BS7671 as a ‘TT’ system).

(b) Distribution Company Earthed (TN-S): the Distribution Company provides a connection to the Customer’s Main Earth Terminal, using the distribution network Earthing system, generally via the armouring or metallic sheath of the main incoming supply cable (referred to in BS7671 as a TN-S system).

These two types of earthing system are illustrated in appendix 6.

7.2.2 The type of earthing system must be requested by the Customer and agreed with the Distribution Company. The type of earthing system must be stated on the Installation Certificate and clearly labelled at the Main Distribution Board.

7.2.3 In all cases the neutral conductor provided by the Distribution Company shall be separate from any Earth Conductor and shall be solidly Earthed only at the HV/LV distribution substation.

7.2.4 Both Customer Earthed and Distribution Company Earthed systems must be fitted with an earth leakage device as specified under regulation 6.4.

7.2.5 For either a Customer Earthed system or a Distribution Company Earthed system the maximum Earth Resistance measured at the Customer’s Main Earth Terminal shall be 5 ohms. This will normally be checked before commissioning in the presence of the



Distribution Company representative. (Methods of measuring Earth Resistance are shown in appendix 25).

7.2.6 The Main Earth Terminal and Earth Electrodes must be regularly inspected and tested in accordance with the test procedures described under chapter 9.

7.3 Earth Electrodes

7.3.1 For a Customer Earthed system Earth Electrodes must be provided and installed by the Customer and connected to the Main Earthing Terminal (but not connected to the earth sheath or armouring of the Distribution Company cables).

7.3.2 For Premises consisting of more than one building, where a Customer Earthed system is used, Earth Electrodes must be provided at each building that is more than 30m distance from the main Supply Intake.

7.3.3 Earth Electrodes will normally comprise of 20mm or 16mm diameter steel-cored copper rods driven to a minimum depth of 3 meters. The top of each Earth Electrode must be housed inside a 300mm x 300mm x 300mm inspection pit which is clearly labeled and accessible for routine testing. Alternative types of Earth Electrodes may be used with prior approval of the Distribution Company (e.g. plate or wire mesh type).

7.3.4 Where more than one Earth Electrode is required to achieve the maximum Earth Resistance value stated in clause 7.2.5 above these must be positioned at a minimum of 6 meters apart (see BS7430 for further advice on spacing of Earth Electrodes).

7.3.5 The condition of the ground in which an Earth Electrode is placed must be taken into account to ensure its long term performance (taking into account potential corrosion effects etc). In particular, the ground moisture content is of critical importance and the use of proprietary chemical / salt materials may be used around the Earth Electrode to maintain moisture content.

7.3.6 Where it is proposed to use underground metallic structures as part of the Earth Electrode system (e.g. structural steel or concrete reinforcing rods) this must be approved by the Distribution Company prior to commencing construction.

7.3.7 For supplies above 500A rating at least two Earth Electrodes must be provided.

7.3.8 The metal parts of gas, water or other services shall not be used as Earth Electrodes.

7.4 Earth Conductors

7.4.1 Types of Earth Conductors in an installation include the following (see appendix 8):

‘main’ Earth Conductors: - conductors from Earth Electrodes to the Main Earth Terminal - conductors from the Main Earth Terminal to Distribution Boards - conductors between distribution boards

‘Circuit’ Earth Conductors: - conductors from Distribution Boards to Final Circuits and

Appliance connection points ’Appliance’ Earth Conductors:

- conductors from Appliance connection points (e.g. 3 pin socket



outlets) to an Appliance, normally within a sheathed cable or flex - conductors connecting Exposed Metallic Parts of an Appliance

7.4.2 All Earth Conductors must be covered with green/yellow PVC insulation and terminated with purpose made lugs or fixings.

7.4.3 The connection of Earth Conductors to Earth Electrodes shall be made with corrosion resistant clamps. Where Earth Conductors are buried below ground they shall be mechanically protected (e.g. in plastic or metal duct or pipe).

7.4.4 The connection of Earth Conductors to the Main Earthing Terminal shall be made using purpose made lugs or other fixings and the connection must be clearly labelled as shown in appendix 8.

7.4.5 All Circuits shall have an Earth Conductor sized in accordance with appendix 11, and in general run alongside the phase and neutral conductors. Such arrangements should minimise the risk of an Earth Conductor being damaged or disconnected without any damage or fault indication being detected via the phase conductors.

7.4.6 For metal sheathed or armoured cables the sheath/armouring may be used as the Earth Conductor where it is rated to the equivalent of the conductor sizes shown in appendix 11. However, for underground cables which are laid within a Customer’s Premises (e.g. between separate buildings), a separate earth cable shall be laid alongside the power cable.

7.4.7 The use of metal conduits, trunking, busbar trunking or switchgear metal enclosures as Earth Conductors shall not be permitted without the prior approval of the Distribution Company. In such cases the provision of additional measures such as resistance measurements and/or supplementary Earth Conductors will normally be required.

7.4.8 No switches, isolators or circuit breakers may be installed in the electrical path of any Earth Conductor. However, removable links may be installed for the purpose of allowing testing at the Main Earth Terminal, which must be clearly labelled: “WARNING SAFETY EARTH CONNECTION – DO NOT REMOVE” (see appendix 8).

7.5 Exposed Metallic Parts

7.5.1 All Exposed Metallic Parts of an Installation which can be touched by persons must be connected to Earth via Earth Conductors which meet the requirements of regulation 7.4.

7.5.2 Exceptions to clause 7.5.1 may include internal parts of equipment or Appliances which cannot be accessed by persons without first disconnecting the electricity supply.

7.5.3 Class I Appliances which include Exposed Metallic Parts must be provided with a suitable connection point or plug & socket arrangement which includes connection to the circuit Earth Conductor. Class II Appliances do not require an Earth connection but all connection points in an Installation must include an Earth Conductor for future use.

7.5.4 Items within an Installation where it is mandatory for a connection to be made to an Earth Conductor are listed in appendix 13.



7.6 Equipotential Bonding Conductors

7.6.1 Equipotential Bonding Conductors are required to connect together Extraneous Metallic Parts, metalwork or structures in a Premise, which are not part of the Electrical Installation, but which may become live during an electrical fault condition. Extraneous Metallic Parts may also present an alternative conductive (or partly conductive) path to Earth aside from main or circuit Earth Conductors and therefore must be Bonded together to prevent a difference in potential which could cause electric shock.1

7.6.2 Items requiring Equipotential Bonding can include metallic pipes (particularly those connected to underground services such as water supply), steel beams, water tanks, baths, sinks and washbasins etc. Examples of typical Equipotential Bonding arrangements are given in appendix 8.

7.6.3 It is not necessary to provide Equipotential Bonding for standalone metallic items which:

(a) do not pose any risk of providing a conductive path to Earth;

(b) do not pose any risk of providing a conductive path to any other Earthed part of the Electrical Installation;

(c) do not pose any risk of becoming live as a result of an electrical fault in the Installation (i.e. are sufficiently remote from any Circuit or Appliance);

(d) are out of reach of persons Such items may include metal doors, window frames, drain covers, small metallic fixings (e.g. screws and brackets), etc.

7.6.4 The sizing of Equipotential Bonding Conductors is given in appendix 11.

7.6.5 The point of connection of an Equipotential Bonding Conductor to any item must be labelled: ‘SAFETY EARTH CONNECTION – DO NOT REMOVE’, as illustrated in appendix 8.

7.7 Earth Loop Impedance

7.7.1 The Earth Fault Loop Impedance (Zs) is defined as the total impedance presented to an earth fault current, comprising the impedance of the following parts of an Installation (illustrated in appendix 15):

(a) the Circuit Earth Conductor;

(b) the Main Earth Terminal;

(c) the main Earth Conductors connecting to local Earth Electrodes (TT system) or the Distribution Company Earth (TN-S system);

(d) the path of earth fault current through the general mass of Earth, or through the earth sheath or armouring of the Distribution Company cable;

(e) the neutral earth connection at the Distribution Company transformer;

(f) the distribution transformer winding;

(g) the phase conductors of the Circuit back to the point of fault.

1 Further explanation of the principles of Equipotential Bonding is provided in appendix 8.



7.7.2 All Installations must be designed and tested such that the Earth Fault Loop Impedance is of a sufficient value to operate overcurrent protective devices within 0.4 seconds.

7.7.3 The maximum Earth Fault Loop Impedance values to ensure a disconnection time of 0.4 seconds for MCB devices is given in appendix 15.

7.7.4 The method for testing Earth Fault Loop Impedance is given in appendix 26.

7.7.5 Where the value of external Earth Fault Loop Impedance Ze is known the internal loop impedance my be added to this by measuring the longest Circuit and using the conductor resistance values given in appendix 15.

7.8 Lightning Protection

7.8.1 Lightning protection systems and associated earth electrodes shall be kept separate from the electrical Installation earthing system.

7.8.2 A minimum distance of 7m shall be provided between lightning protection earth electrodes and the Installation Earth Electrodes.

7.8.3 Lightning protection systems should be designed, installed and maintained in accordance with BS 6651.

7.9 Functional Earthing

7.9.1 Functional Earthing systems (e.g. for the purpose of radio frequency noise reduction, or filters for computers etc) must be kept separate from the Installation Earthing system.

7.9.2 Where it is desired to connect a Functional Earthing system with the main Installation Earth this must be approved by the Distribution Company prior to construction.



8. SELECTION OF COMPONENTS AND INSTALLATION REQUIREMENTS

8.1 Socket Outlets and Plug Connectors

8.1.1 For domestic Installations all single phase plugs and socket outlets shall comply with BS1363 (3 square pins with all three holes covered by a tamper proof shutter) and must be fitted with a switch. For domestic Installations the use of any other type of plugs/sockets, such as BS546 (3 round pins, 15A or 5A) is not permitted.

8.1.2 For non-domestic Installations either BS1363 or BS546 type plugs and sockets are permitted, although the latter must only be used for specialist applications (i.e. Appliances on special dedicated Circuits where it is desirable not to intermix with other normal use Appliances; an example would be table lamps in hotel rooms which are switched from a common point supplying BS546 5A sockets). Further illustration of the use of BS546 sockets is shown in appendix 23.

8.1.3 The use of 2 pin plugs such as the Euro CEE/14 plug and the ‘Shuko’ CEE/7 plug is strictly prohibited, unless provided with an approved adapter converting such plugs for use on BS1363 type sockets (see appendix 23).

8.1.4 An allowable exception to clause 8.1.1 is the use of shaver supply units in bathrooms, complying with BS3535. For these type of socket outlets, which are isolated for safety through a 2 winding isolating transformer, a 2 pin plug may be used but which must also comply with BS3535.

8.1.5 No socket outlets shall be installed in a bathroom except for a socket outlet complying with BS 3535 (shaver socket outlet including a 2 winding isolating transformer).

8.1.6 Three phase and industrial plugs and socket outlets shall comply with BS 4343. The rating of three phase socket outlets shall be selected according to the load of Appliance or equipment to be connected.

8.1.7 Socket outlets accessible for normal use should be positioned at a height of 450mm above floor level or 100mm above work surfaces (e.g. kitchen work top). In some cases low level or ‘skirting’ height may be used for special applications (e.g. offices) at a minimum of 100mm above the floor level.

8.1.8 Socket outlets in kitchens or other areas where water is used must be positioned at least 1.5 m away from sources of water (e.g. sinks, basins, filter units, supply taps).

8.1.9 The recommended minimum number of socket outlets for domestic Installations is given in appendix 24. Single or double socket outlets may be used according to the anticipated usage.

8.2 Switches and Isolators

8.2.1 All switches provided for local isolation of appliances and equipment (including lighting) shall comply with BS 3676. The rating of switches shall be selected based on the expected load, taking into account any capacitive or inductive effects.

8.2.2 For outdoor locations or damp/wet areas, weather protected switches should be used



(BS 3676).

8.2.3 For areas with higher than normal risk of fire or explosion gas sealed switches should be used (BS 5345). E.g. in gas storage areas, battery rooms etc.

8.2.4 The normal mounting height for switches shall be 1.3m from floor level.

8.2.5 Switches with neon indicators should be provided for appliances such as water heaters, air conditioning units, fridges and freezers, where the visual indication of a continuous supply is desirable.

8.2.6 Double pole switches must be provided for water heaters, air conditioning units and other fixed Appliances operating with or near water supplies.

8.2.7 Cooker control units (isolators) for domestic Installations should comply with BS 4177. The use of cooker control units with an integral 3 pin socket outlet is prohibited (due to the need for earth leakage protection to cover all 3 pin socket outlets).

8.2.8 Flexible cables from switches / isolators to fixed appliances (such as water heaters, cookers etc) must be adequately rated and securely fixed with a purpose made flex outlet plate (which may be integral or separate to the switch / isolator unit). See appendix 23.

8.3 Lighting

8.3.1 Lighting Circuits will normally be fed from 6A, 10A or 16A MCBs from a Final Distribution Board.

8.3.2 Switching of Circuits containing discharge lighting or other lighting with high inductance may require special consideration due to high switching voltages that may occur. As a guide, the rating of switches for discharge lighting circuits should be twice that of other circuits with the same load current.

8.3.3 Mains operated clocks may be connected to lighting circuits provided that a fused outlet is provided.

8.3.4 All luminaires must be connected to Final Circuits using a ceiling rose or other purpose made connection point and not directly to such Circuits. Heat resistant cables between luminaires and connection points should be used where necessary.

8.3.5 Lighting Circuits in false ceilings or voids must be installed in conduit or trunking in compliance with clauses 8.5.9 and 8.5.10. However, short lengths (less than 3m) of flexible or sheathed cables may be provided between a lighting connection point or ceiling rose and a luminaire, provided that provision is made for future access and maintenance.

8.3.6 Luminaires and other light fittings must be installed with due consideration to the weight taken by fixings and supports, and the need for adequate ventilation and heat dissipation.

8.3.7 Outdoor lighting should be of suitable weatherproof construction with appropriate connection points and fittings.

8.3.8 Underwater lighting should preferably be supplied at low voltage or should be supplied



via a 10mA RCD device.

8.4 Conduits and Trunking

8.4.1 All plastic conduits and trunking must comply with either BS4607 or BS6053 or BS6099 and be suitable for the ambient conditions expected.

8.4.2 All metal conduits and trunking must comply with either BS4568, BS-EN 60423 or BS-EN 50086. Flexible conduits must be of metal construction, PVC covered and comply with BS731 part 1.

8.4.3 Metal conduits may not be used as the sole means of providing an Earth (separate Earth Conductors must be run inside the conduit).

8.4.4 Plastic conduits or trunking must not be used in situations subject to higher than normal temperatures or fire risk (e.g. near industrial machinery, generator rooms, workshops, petrol stations etc).

8.4.5 Conduits and trunking must be installed so as to provide ease of access to cable Circuits throughout the route. Sufficient inspection plates and pulling points must be provided to enable inspection, repair and drawing out of cables throughout the life of the Installation.

8.4.6 The minimum internal radius on any bend or elbow fitting in a conduit shall be 2.5 times the diameter of the conduit. Elbow fittings of trunking may be 90 degree formation if the cover is removable so that cables may be installed without the need for pulling through.

8.4.7 Cable trunking shall generally be run exposed or otherwise accessible after installation, throughout its length for the purpose of removing/installing cables.

8.4.8 Under-floor trunking may be used for the combined provision of power, telecommunications and other circuits provided that adequate segregation between different types of circuits is provided, as well as suitably sealed service boxes and connection boxes.

8.4.9 The maximum number of cables for typical sizes of conduits and trunking are given in appendix 18.

8.4.10 Where conduits or trunking are installed on the Distribution Company’s side of the Customer Connection Point, these must be provided with a means of locking or sealing against unauthorised interference.

8.5 Cables and Final Circuits

8.5.1 For normal fixed wiring within premises PVC (thermoplastic), rubber (thermosetting) or XLPE insulated, stranded copper conductor cables shall be used, complying with BS6004, BS6346 or BS5467. For locations subject to a higher than normal risk of interference or damage armoured cables are recommended.

8.5.2 For locations with higher than normal fire risk mineral insulated copper sheathed cables shall be used, complying with BS 6207.

8.5.3 General purpose flexible cables and cords for appliances shall be PVC insulated, with a



PVC over-sheath, stranded copper conductors, and comply with BS 6500/6004.

8.5.4 Cables for high temperature appliances (e.g. electric heaters, irons, pendant lighting) shall be heat resistant rubber insulated, with over-sheath, stranded copper conductors, and comply with BS 6141.

8.5.5 Cables under repetitive mechanical strain (e.g. lifts, heavy outdoor machinery etc) shall comply with BS 6977.

8.5.6 Cables for meter tails (at 230V) shall normally be single core, PVC insulated, with over-sheath, and comply with BS 6004.

8.5.7 The size of cables should be selected according to the expected load and voltage drop, using appendix 16. The maximum voltage drop from the Customer Connection Point to the remote end of any Final Circuit should be 4%.

8.5.8 The use of single core armoured cables is normally prohibited due to the possibility of induced heating effects. However, such cables may be used where there is an exceptional need, with the written consent of the Distribution Company and where adequate precautions are taken to avoid induced heating effects (e.g. appropriate spacing of phases to balance induced currents, earthing at one end only or the use of non ferromagnetic armouring and cable glands).

8.5.9 In general, all cables which are not armoured, must be installed in plastic or metal conduit or trunking.

8.5.10 In particular, cables running through inaccessible areas such as walls, floors and ceilings must be installed in conduit or trunking so as to be withdrawable in the future. In such a case, suitable inspection plates and pulling out points should be provided.

8.5.11 Exceptions to clause 8.5.9 may be allowed only for sheathed, flexible or armoured cables which will remain accessible but in locations free from any undue risk of damage or interference (e.g. above head height, or in unoccupied areas). Such cables should be securely supported by cable clips or other fixings at suitable intervals.

8.5.12 All cables must be installed between purpose made termination points (switches, junction boxes, distribution boards) and joints between such points are strictly prohibited.

8.5.13 The colour identification for cables is given in appendix 17.

8.5.14 The sizing of cables, including voltage drop and derating factors are given in appendix 16.

8.5.15 The sizing of Final Circuits should be made according to the expected and future load requirements, taking into account the diversity of use of Appliances and equipment. The guidelines given in appendix 5 may be used to calculate Final Circuit ratings.

8.5.16 Radial (or ‘spur’) Circuits should be provided to large Appliances, particularly those in continuous or near continuous operation, or those of importance to safety or other important functions within a Premise. Examples include: main water pumps, air conditioning units, water heaters, room heating, fire or intruder alarms, cookers and ovens etc.

8.5.17 Ring Circuits should be provided to areas within a property which can be most



economically served by several Appliances sharing the same cable feed, arranged in a loop, from one circuit breaker on the Final Distribution board. This would be particularly suitable where Appliances are expected to operate at diverse times of the day. Ring Circuits would typically be installed in bedrooms, living rooms, kitchens (except major appliances such as cookers), partitioned office areas etc.

8.5.18 Circuits supplying a kitchen must not be used to supply any other area. However, ceiling lighting circuits from a kitchen may be common to other areas.

8.5.19 For domestic premises all circuits supplying one room shall be on the same phase, other than for kitchens, and for ceiling lighting.

8.5.20 Typical radial and ring circuit arrangements for domestic premises are shown in appendix 22.

8.6 Distribution Boards

8.6.1 All Distribution Boards must be factory assembled and comply with BS EN 60439.

8.6.2 Distribution Boards must be of robust construction, capable of withstanding expected electrical, thermal, and environmental stresses in normal operation and during faults.

8.6.3 Apparatus forming part of the assembly of Distribution Boards shall have electrical isolation clearances sufficient to withstand normal voltages, surge voltages and creepage as defined in BS EN 60439-1.

8.6.4 Each Distribution Board must have a neutral bar which is mounted on insulators and which has a sufficient number of terminal points of adequate size for the largest cable expected to be used.

8.6.5 Each Distribution Board must have an Earth bar which has means of connection to the incoming Earth Conductor and cable gland of the incoming cable.

8.6.6 Distribution Boards must have split busbars where different levels of Earth Leakage protection are required (generally 100mA RCD and 30mA RCD, with additional RCBO devices for more sensitive protection, such 10mA for swimming pools).

8.6.7 Each floor of a Premises shall be provided with at least one Sub or Final Distribution Board installed in an easily accessible location.

8.6.8 Single phase Distribution Boards are permitted for loads up to a maximum of 9kW.

8.6.9 The phase and neutral busbars shall be identified by the colours given in appendix 17.

8.6.10 The phase and neutral conductors shall be of the same cross sectional area.

8.6.11 Provision of neon indicators, voltmeters and ammeters integral to Distribution Boards is preferred where reasonably practicable and is required for Distribution Boards rated above 400A.

8.6.12 Replaceable fuse links are not preferred in Customer Distribution Boards (MCBs or equivalent should be provided). The use of rewireable fuse links is prohibited.

8.6.13 All Distribution Boards must be installed in locations easily accessible for inspection, operation and maintenance. Such locations must be secured from unauthorised



interference, particularly from children.

8.6.14 Distribution Boards shall not be installed in locations where water is used (e.g. kitchens, bathrooms, pump rooms), within 2m of any pipe or other source of water, or in difficult to access positions.

8.6.15 Distribution Boards must be provided with sufficient numbers of Protective Device positions (e.g. MCBs) including spare positions (approximately 20% spare positions are recommended).

8.7 LV Switchboards

8.7.1 LV switchboards, consisting of cubicle panel switchgear, may be provided for high current ratings where pre-fabricated Distribution Boards of sufficient rating are not available. LV switchboards must consist of type tested assemblies which satisfy the requirements of BS 5486 or BS-EN 60439.

8.7.2 Switchboards must be located in a dedicated room with due consideration to safe access and egress of persons for future maintenance, repair and replacement work.

8.7.3 Switchboards rated above 400A must be provided with instruments for voltage, current, maximum demand and power factor measurement, as well as phase indicating lamps.

8.7.4 Switchboards rated at 1600A and above must be provided with earth fault relays and overcurrent relays.

8.7.5 Where more than one incoming supply cable is provided at the Supply Intake these should be connected to separate switchboards (or separate sections of the same switchboard) which have the facility for interconnection through a bus coupler circuit breaker. In order to prevent the parallel connection of the incoming supply cables the bus coupler circuit breaker should be interlocked to prevent closing when both incoming supply cables are live.

8.7.6 All busbars in switchboards must be tinned copper, rigidly supported, and insulated throughout their length. The neutral and earth busbars must run throughout the length of the switchboard. The neutral busbar must be of the same cross section area as the phase busbars.

8.7.7 The main incomer circuit breakers should be clearly marked and left unlocked to allow immediate operation in an emergency.



9. INSPECTION, TESTING AND CERTIFICATION

9.1 Installation Certificates

9.1.1 Every new Installation shall, on completion and before being energised, be inspected and tested by a Licensed Contractor who shall duly complete the relevant test reports and submit these to the Distribution Company.

9.1.2 In order to verify compliance with these Regulations the Licensed Contractor shall complete and sign an Installation Certificate in the format shown in appendix 3, as shall the designer and installer of the Installation (may be the same person/company).

9.1.3 Two original copies of the Installation Certificate and associated test results shall be provided, one to the Customer / Owner of the Premises, and one to the Distribution Company. An additional copy must be affixed at the Main Distribution Board or Supply Intake position.

9.1.4 The Distribution Company shall verify on site the test results for Earth Resistance at the Main Earth Terminal and inspect or test other items as deemed appropriate, including as a minimum:

(a) connection of conductors;

(b) identification of conductors and labelling of equipment;

(c) routing of cables and their protection against mechanical damage;

(d) cross section of conductors for current carrying capacity and voltage drop;

(e) connection of single pole devices for protection/switching in phase conductors only;

(f) correct positioning and connection of accessories and equipment;

(g) presence of fire barriers and protection against thermal effects;

(h) methods of protection against electric shock - both direct and indirect contact;

(i) inspection of integrity of Main Earth Conductors and Earth Electrodes.

9.1.5 The Distribution Company may carry out intermediate inspection(s) prior to the final inspection mentioned in clause 9.1.4 above, in order to verify compliance of concealed parts of the Installation (e.g. conduits, buried cables and Earth Conductors).

9.1.6 Any extension or alteration to an electrical Installation will require a Licensed Contractor to issue an amended Installation Certificate, together with a copy of the original certificate, and stating the details of the work carried out.



9.2 Routine Inspection and Testing

9.2.1 The responsibility for routine inspecting and testing of Electrical Installations lies with the Owner of the Premises who shall request the services of a Licensed Contractor at the following intervals following the first inspection and certification:

Internal Installation

External Installation

Domestic 5 years 5 years

Non-Domestic (commercial, industrial, farms etc)

3 years 3 years

Premises used by the public (schools, hospitals, hotels, malls, parks, wedding tents, mosques)

3 years 2 years

Special locations: Construction Sites Swimming pools and fountains Street lighting and equipment

1 year 1 year 1 year

1 year 1 year 1 year

9.2.2 Electrical Installations which were installed before the date of commencement of these Clauses (1.1.2) shall be inspected and tested within the time indicated above from the date of commencement.

9.2.3 Routine inspection and testing shall be recorded on the standard forms shown in appendix 31 and appendix 32 and shall include:

(a) continuity of Ring and Final Circuit conductors;

(b) continuity of Earth Conductors including Equipotential Bonding Conductors;

(c) insulation resistance;

(d) protection against Direct Contact;

(e) polarity;

(f) Earth Fault Loop Impedance;

(g) Earth Electrode Resistance.

9.2.4 The continuity test shall be carried out with an instrument having a no load voltage between 4 volts and 24 volts d.c or a.c. and a short circuit current not less than 200mA, in accordance with the procedure in appendix 27.

9.2.5 The insulation resistance tests between live conductors and between each live conductor and earth shall be measured with a test voltage of 500V d.c, in accordance with the procedure in appendix 28.



10. SELV - SEPARATED EXTRA LOW VOLTAGE SYSTEMS

10.1 Source of SELV Power

10.1.1 For a Separate Extra Low Voltage system the source of power shall not exceed “extra low voltage” i.e. 50V ac or 150V dc between conductors or to earth.

10.1.2 The source of SELV power shall be provided by either:

(a) a safety isolating transformer complying with BS353, in which there is no connection between the output winding and the body or the protective earthing conductor, if any;

(b) a battery source.

10.1.3 All components of a SELV system including conductors, switches, relays etc. shall be physically separated from those of any other live system.

10.1.4 No Exposed Metallic Part of a SELV system shall be connected to any of the following:

(a) Earth;

(b) any Earthed Metallic Part of another system or Extraneous Metallic Part;

(c) an Earth Conductor of any system.

10.1.5 Insulation against Direct Contact of the conductive parts of a SELV system is required if the operating voltage is above 25V ac or 60V dc. Insulation is not required if the operating voltage is below these values.



11. POWER FACTOR CORRECTION

11.1 General Requirements

11.1.1 The power factor of every Installation shall be controlled to between 0.9 lagging and unity. In order to achieve this value power factor correction capacitors may be employed for individual compensation, for group compensation, or for centralised compensation.

11.1.2 In order to reduce the reactive currents within an Installation, and provide for more efficient supply of power, the power factor correction capacitors shall be installed as close to the load as possible.

11.1.3 Power factor correction capacitors shall normally be of dry or oil filled, encapsulated, sealed type. Note: the use of oil containing PCB (poly-chloro biphenyls) is strictly prohibited.

11.1.4 Power factor correction capacitors shall be provided with a means of prompt discharge on disconnection of the supply voltage. The discharge Circuit shall be permanently or automatically connected to the capacitor. Manual means of switching or connecting the discharge circuit shall not be permitted.

11.1.5 In general all air conditioning units, motors, large electrical machines, fluorescent or discharge lighting etc., shall be provided with integral power factor correction.

11.1.6 For large Installations overall group compensation at the Main Distribution Board may be permitted.

11.1.7 For group compensation, automatically regulated capacitor banks shall be used which shall provide, as far as possible, a smoothed power factor throughout the range of operation. The rating of each capacitor step shall be such that the initial steps shall have less kVAr rating and the rating of subsequent steps shall be increased progressively to the desired maximum kVAr.

11.1.8 For induction motors the capacitor rating may not exceed 90% of the no load reactive power of the motor (in order to avoid the high over voltage across the terminals due to the occurrence of self excitation on run down condition of the motor).

11.1.9 The occurrence of harmonics while employing variable speed drives, welding machines or similar devices in Circuits can lead to disturbance in the system and may cause capacitor failure. In order to eliminate or reduce this risk harmonic filters should be employed in series with capacitors.

11.2 Specifications

11.2.1 Capacitors shall be capable of continuous operation provided that none of the following limitations are exceeded:

(a) 135% of the rated reactive power;

(b) 110% of the rated voltage rms, including harmonics but excluding transients;

(c) 180% of the rated current rms, including fundamental and harmonic current.



11.2.2 Capacitors shall be equipped with built in discharge resistors sized to ensure safe discharge of the Capacitor to less than 50V in one minute after a switch off.

11.2.3 Each capacitor shall be provided with a permanent nameplate, which includes the following information:

(a) name of the Manufacturer;

(b) serial No;

(c) year of Manufacture;

(d) rated reactive power;

(e) rated voltage rms;

(f) number of Phases;

(g) rated frequency;

(h) statement of discharge device;

(i) short circuit current;

(j) statement of liquid fill (if any).

11.2.4 Capacitors shall be able to withstand up to 30 times In caused by harmonics.

11.2.5 Capacitors shall have provision for effective earth connection of the case to the capacitor mounting frame and to the circuit Earth Conductor.

11.2.6 Capacitors and related components such as regulators, indicating instruments, contactors, etc., shall be capable of withstanding local environmental conditions.

11.2.7 Contactors shall be designed for capacitive switching and shall be able to withstand switching surges. Contactors shall be rated for 1.5 to 1.8 times the normal rated current of the capacitor and shall isolate all three phases on switch off.

11.2.8 Each capacitor step shall be protected by means of HRC fuses (current limiting type).

11.2.9 The capacitor panel must be provided with a suitably rated main incomer isolating switch. This shall be a three pole isolator or MCCB as the case may be. The handle of the incomer isolator shall be interlocked with the door to ensure that capacitor bank is de-energized when the door is open.

11.2.10 Capacitor banks shall not be a part of the motor control centre, main LV panel or sub-main panel; it shall be accommodated in a separate cubical.

11.2.11 In addition to the requirements stated above capacitor banks shall conform to the latest relevant international standards, including the following:

(a) LV switchboard IEC 60439-1

(b) Degree of protection IEC 60529

(c) LV circuit breaker and switch-disconnector IEC 60947 (1 to 5)

(d) Power factor correction capacitors IEC 60831 (1-2)

(e) Power factor regulator IEC 60664 and IEC 1010-1

(f) Capacitor switching contactors IEC 60070 and IEC 60831

(g) Detuned reactors IEC 60289 and IEC 60076



12. MOTORS AND GENERATORS

12.1 Electric Motors and Starters

12.1.1 The installation of electric motors supplied from the LV distribution system is permitted up to a maximum of 5HP (3.7kW) for single phase and 150HP (110kW) for 3 phase. Where it is proposed to install more than one motor of rating 150HP the relevant diagrams, operation information, protection arrangements etc should be provided to the Distribution Company in order to gain approval for connection.

12.1.2 All electric motors shall be adequately protected against overload, short circuit, loss of one or more phases and voltage dips etc. as appropriate for each application.

12.1.3 All electric motors above 5HP must be provided with mechanical overload protection.

12.1.4 All motors above 1HP shall be provided with current limiting starting equipment to effectively keep the starting current within the following limits:

Rating of Motor Max. Permissible Starting Current

1 Hp to 5 Hp 5 Times full load current

Above 5 HP and up to 50 HP 2 Times full load current

Above 50 HP and up to 150 HP 1.5 Times full load current

12.2 Standby Generators

12.2.1 Installation and connection of standby generators in any Installation, for the purpose of maintaining power in the case of a failure of the incoming supply, shall be permitted only with the prior approval of the Distribution Company.

12.2.2 The changeover circuit breaker shall have 4 poles for a 3 phase generator and 2 poles for a single phase generator, to ensure that all live and neutral conductors are disconnected at the same time.

12.2.3 The installation and changeover arrangements must ensure that there is no possibility of paralleling the generator and incoming mains supply. If paralleling arrangements are required these must be specifically assessed and approved by the Distribution Company. The general requirements for such arrangements are provided in the Electricity Distribution Code – Annex 1: “Engineering Recommendation No. 3 - Connection of Embedded Generation Plant up to 5MW”.



13. SPECIAL LOCATIONS

13.1 Outdoor Sites

13.1.1 Outdoor sites may include wedding tents, construction sites, parks, farms, caravans etc, all of which must comply with the requirements of these Regulations.

13.1.2 In particular the following provisions must be given special attention for outdoor sites:

(a) All cables which are not installed in conduit or trunking must be armoured and adequately protected against accidental or deliberate interference by persons, and against the effects of weather.

(b) Outdoor electrical Installations should have a minimum ingress protection level of IP53 (see appendix 19);

(c) Cables passing on or over walkways and access roads must be adequately enclosed to avoid Danger;

(d) Particular attention should be given to the location, signing and protection of equipment where the public may have access, in particular children;

(e) equipment should be located and adequate notices be displayed to that emergency disconnection of the electricity supply can be effected without delay. Locking arrangements should be such that these can be removed in an emergency (e.g. panic bar or keys available in break out box).

(f) The requirements for periodic testing must be strictly complied with (regulation 9.2).

(g) Earth leakage protection must be provided in line with regulation 6.4.

13.2 Street Lighting, Traffic Signals and Signboards

13.2.1 The general safety requirements of these Regulations shall apply to electrical supplies to street lighting, traffic signals and signboards.

13.2.2 The detailed design, installation arrangements, and other special requirements for the above types of supplies shall be specified by the Distribution Company providing supply.

adwea wiring regulation

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