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މޯލްޑިވްސް އެނާރޖީ އޮތޯރޓި ީ

 MALDIVES ENERGY AUTHORITY

 MALDIVES ENERGY AUTHORITY 

INSTALLATION STANDARDS REGULATIONS

INSTALLATION STANDARDS 

TABLE OF CONTENTS 

CHAPTER 1) GENERAL REGULATION ...................................................................................................................... 2

SECTION I)GENERAL PROVISIONS.................................................................................................................................... 2

SECTION II)GLOSSARY................................................................................................................................................... 3

SECTION III)INTERNATIONAL STANDARDS REFERENCE LIST.................................................................................................... 4

CHAPTER 2) SAFETY FOR LIVING SPECIES AND GOODS .......................................................................................... 5

SECTION I)GENERAL SPECIFICATIONS............................................................................................................................... 5

SECTION II)PROTECTION FOR SAFETY............................................................................................................................... 8

CHAPTER 3) STANDARDS FOR LV ELECTRICAL INSTALLATIONS (OUTDOOR AREAS AND PUBLIC AREAS).............. 14

SECTION I)GENERAL SPECIFICATIONS............................................................................................................................. 14

SECTION II)STANDARDS FOR LVOVERHEAD LINES IN OUTDOOR AREAS AND PUBLIC AREAS........................................................ 14

SECTION III)STANDARDS FOR LVUNDERGROUND CABLES IN OUTDOOR AREAS AND PUBLIC AREAS.............................................. 18

SECTION IV)STANDARDS FOR LVSWITCHGEAR AND CONTROLGEAR..................................................................................... 26

CHAPTER 4) STANDARDS FOR LV ELECTRICAL INSTALLATIONS (IN-HOUSE AREAS) .................................................. 28

SECTION I)GENERALSPECIFICATIONS......................................................................................... 28

SECTION II)SELECTION AND ERECTION OF ELECTRICAL EQUIPMENT.......................................... 29

CHAPTER 5) STANDARDS FOR MV ELECTRICAL INSTALLATIONS (OUTDOOR AND PUBLIC AREAS AND PRIVATE 

AREAS) ..................................................................................................................................................................... 40

SECTION I)STANDARDS FOR MVOVERHEAD LINES........................................................................................................... 40

SECTION II)STANDARDS FOR MVUNDERGROUND CABLES................................................................................................. 44

SECTION III)STANDARDS FOR MVSWITCHGEAR AND CONTROL GEAR.................................................................................. 60

SECTION IV)PROTECTIONS REQUIREMENTS..................................................................................................................... 61

SECTION V)GENERAL GUIDANCE FOR HVINSTALLATIONS.................................................................................................. 62

CHAPTER 6) STANDARDS FOR GENERATING STATIONS ............................................................................................ 63

SECTION I)GENERALPROVISIONS................................................................................................ 63

SECTION II)PARTICULAR ASPECTS FOR RENEWABLE PLANTS...................................................... 64

SECTION III)MAIN INSTALLATIONCONDITIONS.......................................................................... 65

SECTION IV)MAIN ELECTRICALCONNECTION CONDITIONS......................................................... 68

SECTION V)OPERATION MODES.................................................................................................... 69

CHAPTER 7) INSPECTION AND VERIFICATION .......................................................................................................... 71

SECTION I)INITIAL AND PERIODIC INSPECTIONS AND VERIFICATIONS............................................................................... 71

SECTION II)ON-DEMAND INSPECTIONS AND VERIFICATIONS............................................................................................ 73

CHAPTER I. GENERAL REGULATION 

Section 1. General Provisions 

Article 1. Purpose 

The purpose of these Installation Standards is to set the technical requirements and standards for the design and installation of electrical assets in the Republic of Maldives. 

Article 2. Scope 

This Installation Standards will develop the following aspects: 

1. Standards for LV Electrical Installations (Outdoor and Public Areas) 
2. Standards for LV Electrical Installations (In-House Areas) 
3. Standards for MV Installations (Outdoor and Public Areas and Private Areas) 
4. Standards for Generating Stations 
5. Verification

Article 3. Application 

The contents of this Installation Standards will be mandatory for: 

1. All new Electrical Installations in the Republic of Maldives;  
2. All Electrical Installation in the territory of the Republic of Maldives existent prior to the enactment of these Installation Standards that undergo relevant modifications, major repairs or upgrades; 

For the purposes of this Article, it is considered that relevant modifications and major repairs are those which impact at least 50% of the capacity installed at the Electrical Installation or that impact whole production lines with new circuits and power boxes, regardless of the capacity.

Article 4. Amendments and unforeseen circumstances 

1. The MEA has the authority to approve this Installation Standards and its future amendments, and to decide on any conflicts of interpretation. 
2. If circumstances not envisaged in the provisions of this Installation Standards or divergent interpretations of any provisions included in this Installation Standards should arise, the MEA shall determine what is to be done and notify the Service Providers. This notification shall be added as an Annex to this Installation Standards until an amendment, if necessary, is made. 
3. In assessing the results of this Installation Standards or in case of unforeseen circumstances or if any provision of this Service Providers Code should be found to be unlawful or wholly or partially invalid, the MEA may amend this Installation Standards from time to time. 
4. Prior to any amendment to this Installation Standards, the MEA shall send the amendment proposal to the Service Providers for discussion and for the Service Providers to send their recommendations and suggestions. 
5. The Service Providers’ recommendations are not binding on the MEA, but shall have only the nature of an opinion. The MEA may make further consultation with affected agents and consider other views. 
6. Any decision for amendment to this Installation Standards shall be approved and be published by the MEA.  The MEA shall notify each Service Provider of the amendment approved at least twenty (20) Business Days prior to the revision taking effect.  The revision shall take effect with this Installation Standards deemed to be amended accordingly from and including the date specified in such notification or other such date as directed by the MEA. 

Section 2. Glossary 

Article 5. Definitions 

The following definitions are to be referenced when interpreting this Installation Standards: 

1. Ω : Ohms. 
2. A. : Amperes.  
3. Business Day: working day, every official working day of the week according to the Republic of Maldives’s regulation. 
4. ºC : degree Celsius. 
5. Chimney: passage or vertical channel or pipe that conducts smoke and combustion gases to the outside of a building or the part of such a structure that extends above the roof of the building. 
6. daN: decaNewton. 
7. DB: Distribution Board, where electrical power feed is divided into multiple circuits. 
8. Distribution Network: group of assets and equipment required for the distribution of electricity in the Republic of Maldives, comprising voltage levels not higher than 35 kV. 
9. ELCB: Earth Leakage Circuit Breaker. 
10. Electric Shock: pathophysiological effect of an electric current through the human body as per IEC 60479-1. 
11. Electrical Installation: group of apparatus and associated circuits designed for a particular purpose: generation, conversion, rectification, transformation, distribution or use of electric energy. 
12. Generating Station: power generator or group of power generators located in a same site and their associated equipment and facilities. 
13. h: hour. 
14. IP: Ingress Protection rating or International Protection rating as per IEC 60529. 
15. K : Kelvin. 
16. km. : kilometres. 
17. Low Voltage or LV: any voltage lower than 1 kV that is normalized and approved by the MEA for its use in power distribution in the Republic of Maldives. 
18. m. : metre. 
19. MEC: Maximum Export Capacity. Total electric power measured in kW for which a connection is designed to supply power from the Customer’s premises to the Distribution Network. 
20. Medium Voltage or MV: any voltage from 1 kV up to 35 kV that is normalized and approved by the MEA for its use in power distribution in the Republic of Maldives. 
21. MIC: Maximum Import Capacity. Total electric loading measured in kW for which a connection is designed to supply power from the Distribution Network to the Customer’s premises. 
22. mm. : millimetres.  
23. N. : Newton. 
24. Operator of the Distribution Network: Service Provider in charge of the operation of the Distribution Network. 
25. PEN: Protective Earth and Neutral. 
26. PV: photovoltaic, subtype of solar-based electricity generation. 
27. Renewable Plant: Generating Station whose primary energy source qualifies as renewable energy. It notably includes wind generators and PV panels. 
28. Service Provider: agent licensed by the MEA to develop activities of generation, distribution or sale of electricity or several of them in the Republic of Maldives. 
29. W. : Watt. 

Section 3. International Standards reference list 

Article 6. International Standards Reference List 

1. Any mention to an International Standard in this Installation Standards refers to the latest approved and available version of the Standard or the Standard that replaces it. 
2. The following International Standards are to be referenced when reading this stipulation: 

2.1.        BS-1363: British Standard BS 1363-2 13 A plugs, socket-outlets, adaptors and connection units. Specification for 13 A switched and unswitched socket-outlets. 

2.2.        ISO 23932:2009: Fire safety engineering – General Principles. 

2.3.        IEC 60034: Rotating electrical machines. 

2.4.        IEC 60045: Steam turbines. 

2.5.        IEC 60060: High voltage test techniques. 

2.6.        IEC 60071: Insulation coordination. 

2.7.        IEC 60073: Basic and safety principles for man-machine interface, marking and identification – Coding principles for indicators and actuators. 

2.8.        IEC 60076: Power transformers. 

2.9.        IEC 60183: Guide to the selection of high-voltage cables. 

2.10.       IEC 60287: Electric cables – Calculation of the current rating. 

2.11.       IEC 60364: Electrical Installations for Buildings. 

2.12.       IEC 60445: Identification of conductors by colours or numerals. 

2.13.       IEC 60447: Basic and safety principles for man-machine interface, marking and identification - Actuating principles. 

2.14.       IEC 60449: Voltage bands for electrical installations of buildings. 

2.15.       IEC 60479-1: Effects of current on human beings and live stock. Part 1: General aspects. 

2.16.       IEC 60529: Degrees of Protection provided by enclosures (IP Code). 

2.17.       IEC 60707: Flammability of solid non-metallic materials when exposed to flame sources. 

2.18.       IEC 81346-1: Item designation in Electrotechnology. 

2.19.       IEC 60826: Design criteria of overhead transmission lines. 

2.20.       IEC 60904: Photovoltaic devices. 

2.21.       IEC 62271: High voltage switchgear and controlgear. 

2.22.       IEC 60815: Selection and dimensioning of high voltage insulators intended for use in polluted conditions. 

2.23.       IEC 61140: Protection against electric shock – Common aspects for installations and equipment. 

2.24.       IEC 61400: Wind turbines. 

2.25.       IEC 61439: Low-voltage switchgear and controlgear assemblies 

2.26.       IEC 62446: Grid connected photovoltaic systems - Minimum requirements for system documentation, commissioning tests and inspection.  

CHAPTER II. SAFETY FOR LIVING SPECIES AND GOODS 

Section 1. General Specifications 

Article 7. Scope 

The following provisions shall apply to all Electrical Installations that distribute electricity at low voltage (up to 1,000 V) in both public and in-house areas.  

Article 8. Protection for safety 

1. These standards contain the rules for the design and erection of Electrical Installations so as to provide safety and proper functioning for the use intended. 
2. In-house Electrical Installations are required to be functional, durable, aesthetic and safe to use. Safety in low voltage Electrical Installation is ensured by providing protection against the following main threats: 2.1.           Electric shock; 

2.2.        Thermal effects; 

2.3.        Overcurrent; and 

2.4.        Voltage and electromagnetic disturbances. 

1. Protection against Electric Shock 

3.1.        Persons shall be protected against dangers that may arise from contact with live parts of the installation.  

3.2.        The protection against direct contact can be achieved by one of the following methods: 

3.2.1.     Preventing a current from passing through the body of any person; or 

3.2.2.     Limiting the current which can pass through a body to a value lower than the shock current. 

3.3.        Persons shall be protected against dangers that may arise from contact with exposedconductive parts in case of a fault. The protection against indirect contact can be achieved by one of the following methods: 

3.3.1.     Preventing a fault current from passing through the body of any person; 

3.3.2.     Limiting the fault current which can pass through a body to a value lower than the shock current; or 

3.3.3.     Automatic disconnection of the supply in a determined time on the occurrence of a fault likely to cause a current to flow through a body in contact with exposedconductive-parts, where the value of that current is equal to or greater than the shock current. 

1. Protection against thermal effects 

4.1.        The Electrical Installation shall be so arranged that there is no risk of ignition of flammable materials due to high temperature or electric arc.  

4.2.        In addition, during normal operation of the electrical equipment, there shall be no risk of persons suffering burns. 

4.3.        The installations shall comply with the principles of the international standard ISO 23932:2009, regarding fire safety.

1. Protection against overcurrent 

5.1.        Persons shall be protected against injury and property shall be protected against damage due to excessive temperatures or electromechanical stresses caused by any overcurrents likely to arise in live conductors. The protection can be achieved by one of the following methods: 

5.1.1.     Automatic disconnection on the occurrence of an overcurrent before this overcurrent attains a dangerous value based on its duration and intensity; 

5.1.2.     Limiting the maximum overcurrent to a safe value and duration. 

1. Protection against fault currents 

Conductors, other than live conductors, and other parts intended to carry a fault current shall be capable of carrying that current without attaining an excessive temperature. 

1. Protection against overvoltage 

7.1.        Persons shall be protected against injury and property shall be protected against any harmful effects consequence of a fault between live parts of circuits supplied at different voltages. 

7.2.        Persons shall be protected against injury and property shall be protected against any harmful effects consequence of any excessive voltages likely to arise due to other causes (e.g. atmospheric phenomena or switching overvoltages).  

Article 9. Criteria for safety design of Electrical Installations Electrical Installations shall be designed taking into account: 

1. The protection of persons and property in accordance with Article 8; 
2. The proper functioning of the Electrical Installation for the use intended. 
3. Characteristic of available supply or supplies 

3.1.        Nature of current: a.c. and/or d.c. 

3.2.        Nature and number of conductors: 

3.2.1.     For a.c.: phase conductor(s) 

3.2.1.1.        Neutral conductor; 

3.2.1.2.        Protective conductor. 

3.2.2.     For d.c.: conductors equivalent to those listed above. 

3.3.        Values and tolerances: 

3.3.1.     Voltage and voltage tolerances; 

3.3.2.     Frequency and frequency tolerances; 

3.3.3.     Maximum current allowable; 

3.3.4.     Prospective short-circuit current. 

3.4.        Protective measures inherent in the supply. E.g. earthed (grounded) neutral or mid-wire.  

3.5.        Particular requirements of the supply undertaking. 

1. Nature of demand  

The number and type of the circuits required for lighting, heating, power, control, signalling, telecommunication, etc. Are to be determined by: 

4.1.        Location of points of power demand; 

4.2.        Loads to be expected on the various of demand; 

4.3.        Daily and yearly variation of demand; 

4.4.        Any special conditions; 

4.5.        Requirements for control, signalling, telecommunication, etc. 

1. Emergency supply or supplies 

5.1.        Sources of supply (nature, characteristic) 

5.2.        Circuits to be supplied by the emergency source.

1. Environmental conditions 

6.1.        Typical weather conditions to be withstood by the Electrical Installation; 

6.2.        External agents that constitute a threat to the proper and safe functioning of the Electrical Installation (e.g. dust, salt, water flows, animals). 

1. The cross-section of conductors shall be determined according to: 

7.1.        Their admissible maximum temperature; 

7.2.        The admissible voltage drop; 

7.3.        The electromechanical stresses likely to occur due to short-circuits; 

7.4.        Other mechanical stresses to which the conductors can be exposed; and 

7.5.        The maximum impedance with respect to the functioning of the short-circuit protection. 

1. Type of wiring and methods of installation 

The choice of type of wiring and the methods of installation shall be selected attending to: 

8.1.        The nature of the location; 

8.2.        The nature of the walls or other parts of the building supporting the wiring; 

8.3.        Accessibility of wiring to persons; 

8.4.        The voltage level; 

8.5.        the electromechanical stresses likely to occur due to short-circuits; and 

8.6.        Other stresses to which the wiring can be exposed during the erection of the Electrical Installation or in service. 

1. Protective equipment  

The characteristic of protective equipment shall be determined with respect to their function which may be, e.g., protection against the effects of: 

9.1.        Overcurrent (overload, short-circuit); 

9.2.        Earth-fault current; 

9.3.        Overvoltage; or 

9.4.        Undervoltage and no-voltage. 

The protective devices shall operate at values of current, voltage and time suitably related to the characteristics of the circuits and to the possible sources of danger. 

1. Emergency control 

Where, in case of danger, there is necessity for immediate interruption of supply, an interrupting device shall be installed in such a way that it can be easily recognized and effectively and rapidly operated. 

1. Disconnecting devices 

Disconnecting devices shall be provided so as to permit disconnection of the Electrical Installation, circuits or individual items of apparatus as required for maintenance, testing, fault detection or repair. 

1. Prevention of mutual influence 

The Electrical Installation shall be arranged in such a way that no mutual detrimental influence will occur between the Electrical Installation and non-electrical installations of the building. 

1. Accessibility of electrical equipment 

The electrical equipment shall be arranged so as to afford as may be necessary: 

13.1.       Sufficient space for the initial installation and later replacement of individual items of electrical equipment; and 

13.2.       Accessibility for operation, testing, inspection, maintenance, and repair. 

Section 2. Protection for Safety 

Article 10. Protection of persons against Electric Shock 

1. As a general rule, hazardous-live elements of an Electrical Installation shall not be accessible to persons^[1]and accessible elements shall not be hazardous live. 
2. Live parts of Electric Installations shall be protected by barriers and enclosures to impede direct contact of persons with live parts. 
3. All conductive (which in general means metallic) cases and enclosures of live elements in an Electric Installation shall be connected to the protective earth system of the installation. 
4. The protective earth system of an Electric Installation shall ensure that there is a path to earth for the currents in metallic cases and enclosures with lower resistance that that of the human body as per IEC 61140 and IEC 60364. 
5. Electrical Installations shall be equipped with residual current protection equipment which shall disconnect the power supply to the Electrical Installation to prevent Electric Shocks as per IEC 61140 and IEC 60364. 
6. Live parts at a voltage higher than 25 V. a.c. rms or 60 V. ripple-free^[2]d.c. shall be protected against direct contact by means of: 

6.1.        Barriers or enclosures affording a degree of protection of at least IP65 of IEC 60529, or 

6.2.        Insulation capable of withstanding a test voltage of 500 V. a.c. rms for one (1) minute. 

1. Protection against direct contact shall be granted by means of any of the following solutions: 

7.1.        Insulation of live parts; which can only be removed by destruction. 

7.2.        Protection by barriers or enclosures of at least degree of protection IP2X. Horizontal top surfaces of barriers or enclosures which are readily accessible shall have a degree of protection of at least IP4X of IEC 60529. Barriers and enclosures shall not be opened or removed but with the aid of a specific tool or key, after disconnection of the supply to live parts or where a protection barrier providing protection of at least IP2X of IEC 6029 prevents contacts with live parts. 

7.3.        Protection by obstacles; which prevent unintentional contact with live parts and unintentional bodily approach to live parts. Obstacles may be removed without using a key or toll but shall be secured to prevent unintentional removal. 

7.4.        Protection by placing out of reach: simultaneously accessible parts at different potential shall be placed at least 2.50 m. apart. 

7.5.        Residual current devices with a rated operating residual current not exceeding 30 mA are authorized as additional protection devices in case of failure of main protection devices against direct contact but they can not constitute the unique protection method. 

1. Protection against indirect contact shall be granted by means of any of the following solutions: 

8.1.        Automatic disconnection of supply shall be applied in the event of a fault between a live part and an exposed conductive part or a protective conductor in the circuit or equipment ensuring that a touch voltage exceeding 50 V. a.c. or 120 V. ripplefree d.c. does not persist to cause a risk of harmful physiological effect in a person in contact with simultaneously accessible conductive parts. 

8.2.        Earthing. Exposed conductive parts shall be connected to a protective conductor as specified for each type or earthing arrangement according to IEC 60364-5-54. Exposed conductive parts shall be connected to the same earthing system individually, in groups or collectively.  

1. Protection against faults shall be granted by combination of the following solutions: 

9.1.        Protective-equipontential-bonding which shall comply with the requirements of IEC 61140. 

9.2.        Protective screens, interposed between hazardous-live parts of an Electrical installation, system or equipment and the part being protected shall be connected to the protective-equipotential-bonding system of the installation, system or equipment and comply with the requirements of IEC 61140. 

9.3.        Automatic disconnection of supply. 

Article 11. Protection of persons against thermal effects 

1. Persons, fixed equipment, and fixed materials adjacent to electrical equipment shall be protected against harmful effects of harmful effects of heat development by electrical equipment, or thermal radiation, particularly the following effects:

1.1.        Combustion or degradation of materials; 

1.2.        Risk of burns; and 

1.3.        Impairment of the safe function of installed equipment. 

1. Electrical equipment shall not present a fire hazard to adjacent materials. 
2. Where fixed equipment may attain surface temperatures which could cause a fire hazard to adjacent materials, the equipment shall either: 

3.1.        Be mounted on or within materials which will withstand such temperatures and are of low thermal conductance, or 

3.2.        Be screened from elements of building construction by materials which will withstand such temperatures and are of low thermal conductance, or 

3.3.        Mounted to allow safe dissipation of heat at a sufficient distance from any material on which such temperature could have deleterious thermal effects, any means of support being of low thermal conductance. 

1. Where areas or sparks may be emitted by permanently connected equipment in normal service, the equipment shall either: 

4.1.        Be totally enclosed in arc-resistant material, or 

4.2.        Be screened by arc-resistant material form building elements on which the arcs could have deleterious thermal effects, or 

4.3.        Be mounted to allow safe extinction of the arc at a sufficient distance from building elements on which the arc could have destructive thermal effects. 

Arc-resistant material used for this protective measure shall be non-combustible, of low thermal conductivity, and of adequate thickness to provide mechanical stability. 

1. Fixed equipment causing a focus or concentration of heat shall be at a sufficient distance from any fixed object or building element so that the object or element, in normal conditions, cannot be subjected to a dangerous temperature. 
2. Wherever electrical equipment in a single location contains flammable liquid in significant quantity, precaution shall be taken to prevent burning liquid and products of combustion of the liquid (flame, smoke, toxic gases) spreading to other parts of the building. 
3. The material of enclosures arranged around electrical equipment during erection shall withstand the highest temperature likely to be produced by the electrical equipment. 
4. Forced air heating system shall be such that their heating elements, other than those of central storage heaters, cannot be activated until the prescribed air flow has been established and are deactivated when the air flow is stopped. In addition, they shall have two temperature limiting devices independent of each other which prevent permissible temperatures from being exceeded in air ducts. The frame and enclosure of heating elements shall be of noncombustible material. 
5. All appliances producing hot water or steam shall be protected by design or erection against overheating in all service conditions. Unless the appliances comply as a whole with the appropriate IEC standards, the protection shall be by means of an appropriate non-selfresetting device, functioning independently of the thermostat. If an appliance has no free outlet, it shall also be provided with a device which limits the water pressure. 
6. Live conductors shall be protected by one or more devices for automatic interruption of the supply in the event of overload and short circuits except in case where the overcurrent is limited. 
7. Devices ensuring protection against both overload current and short-circuit current shall be capable of breaking any overcurrent up to and including the prospective short-circuit current at the point where the device is installed. Such protective devices may be:  

Article 12. Protection of Electrical Installations from the effects of overcurrents 

2.1.        Circuit breakers incorporating overload release;

2.2.        Circuit breakers in conjunction with fuses; 

1. Devices ensuring protection against overload current only generally are inverse-time-lag protective devices whose interrupting capacity may be below the value of the prospective short-circuit at the point where devices are installed. 
2. Devices ensuring protection against short-circuit current only may be installed where overload protection is achieved by other means or where overload protection allows to be dispensed with. The devices shall be capable of breaking short-circuit current up to and including the prospective short-circuit current. Such devices may be: 4.1.Circuit breakers with short-circuit release; 

           4.2.     Fuses. 

1. Protective devices against overload current shall be provided to break any overload current flowing in the circuit conductors before such a current could cause a temperature rise detrimental to insulation, joints, termination, or surrounding of the conductors. 
2. The operating characteristic of a device protecting a conductor against overload shall satisfy the two following conditions: 

6.1.        I_B ≤ I_n≤ I_z; 

6.2.        I₂≤1.45 · I_z; Where: 

I_B =current for which the circuit is designed; 

I_Z= continuous current-carrying capacity of the cable; 

I_n= nominal current of the protective device; 

I₂= current ensuring effective operation of the protective device; in practice I₂ is taken as equal to: 

-       The operating current in conventional time for circuit breakers; 

-       The fusing in conventional time for type gI fuses as per IEC 60364; 

-       0.9 times the fusing current in conventional time for type gII fuses as per IEC 60364. 

1. Protective devices against short-circuit currents shall be provided to break any short-circuit current flowing in the circuit conductors before such a current could cause danger due to thermal and mechanical effects produced in conductors and connections. 
2. The prospective short-circuit current at every relevant point of installation shall be determined. This may be done either by calculation or by measurement. 
3. Each short-circuit protective device shall meet both of the following conditions: 

9.1.        The breaking capacity shall be not less than the prospective short-circuit current at the place of its installation, except where the following paragraph applies. 

9.2.        A lower breaking capacity is admitted if another protective device having the necessary breaking capacity is installed on the supply side. In that case, the characteristic of the devices must be coordinated so that the energy let through by these two devices does not exceed that which can be withstood without damage by the device on the load side and the conductors protected by these devices. 

1. All current caused by a short circuit occurring at any point of the circuit shall be interrupted in a time not exceeding that which brings the conductors to the admissible limit temperature. 
2. For short circuits of duration up to 5s, the time t in which a given short-circuit current will raise the conductors from the highest admissible temperature in normal duty to the limit temperature can as an approximation be calculated from the formula: 

𝑺

 = 𝒌 ∙  

𝑰

Where: 

t= duration in seconds; 

S = cross-sectional area in square millimetres; 

I = effective short-circuit current; 

K=  

-       115 for copper conductors insulated with PVC; 

-       135 for copper conductors insulated with general purpose rubber, butyl rubber, cross-linked polyethylene and ethylene propylene rubber; 

-       74 for aluminium conductors insulated with PVC; 

-       87 for aluminium conductors insulated with general purpose rubber, butyl rubber, cross-linked polyethylene and ethylene propylene rubber; and 

-       115 for tin-soldered joints in copper conductors, corresponding to temperature of 160 ºC 

Article 13. Protection of Electrical Installations from the effects of voltage and electromagnetic disturbances 

1. At the transformer substations shall be a earthing system to which shall be connected: 

1.1.        Earth electrodes; 

1.2.        The transformer tank; 

1.3.        Metallic coverings of MV cables; 

1.4.        Metallic coverings of LV cables except where the neutral conductor is earthed via a separate earth electrode; 

1.5.        Earth wires of MV systems; 

1.6.        The exposed conductive parts of MV and LV equipment; and 

1.7.        Extraneous conductive parts present in the Electrical Installation. 

1. The transformer substation shall be connected to cables with suitable earthed metallic coverings, whether MV cables, LV cables or a combination of both. The total length of these cables shall not exceed 1 km. 
2. The earthing resistance of the exposed conductive parts of the transformer substation shall not exceed 1 Ω. 
3. The earthing system of the installation shall be of type TN, TT or IT and comply with the requirements of IEC 60364-4-44. 
4. Equipment shall have at least an impulse withstand voltage as indicated in Table 44B of IEC 60364-4-44, as shown in the following table: 

Table  1 – Required impulse withstand voltage for equipment

1. Protection against overvoltages due to atmospheric conditions shall be provided for those Electrical Installation that include or are supplied from aerial lines, by the installation of: 

6.1.        A surge protection device with a protection level of category II in accordance with IEC 60364-5-53; or 

6.2.        By other means providing at least an equivalent attenuation of overvoltages. 

CHAPTER III. STANDARDS FOR LV ELECTRICAL 

INSTALLATIONS (OUTDOOR AREAS AND PUBLIC AREAS) 

Section 1. General Specifications 

Article 14. Scope  

The following provisions shall apply to all Electrical Installations that distribute electricity at low voltage (up to 1,000 V) in outdoor areas and public areas. Article 15. Standard voltage levels 

1. Although any voltage level up to 1,000 V is considered low voltage, the standard voltage level for LV Electrical Installation shall be: 

                 1.1.     230 V phase-to-neutral and 400 V phase-to-phase for 4-wire 3-phased networks. 

2. The use of voltage levels other than the standard voltage levels here presented shall be authorized by the MEA. 

Section 2. Standards for LV overhead lines in outdoor areas and public areas 

Article 16. Conductors 

1. All conductors used in LV overhead lines shall be made in copper or aluminium and shall be preferably insulated. 
2. Insulated conductors shall: 

2.1.        Be of nominal voltage not lower than 0.6/1 kV and have an insulation covering that grants adequate resistance to open air weather conditions, in particular salty environments. 

2.2.        Have a cross section of at least 10 mm²except for drop-offs that shall have a cross section of at least 6 mm²for connection no larger than 40A. 

3. Bare conductors shall: 

3.1.        Be insulated for a nominal voltage not lower than 0.6/1 kV and be prepared to resist open air weather conditions, in particular salty environments. 

3.2.        Have a maximum tensile strength of at least 410 daN. 

3.3.        Not be installed in areas with trees or with fire hazard. 

1. Conductors can be installed on support structures such as poles or fixed to walls or facades. 
2. Support or guiding wires shall be made in galvanized steel with a tensile breaking stress of at least 800 daN. 
3. The neutral conductor shall not be interrupted except by omnipolar switches and disconnectors that connect and disconnect all phases and the neutral at the same time or that connect the neutral first and disconnect the neutral last. The neutral conductor can also be interrupted in removable joints in the neutral in the proximity of phase conductors’ switches or disconnectors subject to being adequately signalled and requiring a tool for its operation. 
4. The neutral conductor shall be earthed in the low voltage side of the transformer station or the Generating Station that supplies the circuit. 
5. The neutral conductor in TT and TN systems and the protective earth conductor in TN-S systems shall be earthed every 500 m. of line. Article 17. Fittings and accessories 
6. Fittings and accessories installed in LV overhead lines in outdoor areas and public areas shall be adequately protected against corrosion and ageing and shall resist the mechanical efforts to which they may be exposed with a security coefficient of at least that of the anchoring device to which they are connected. 
7. Stays shall be metallic rods or wires protected against corrosion and with a minimum maximum tensile strength of 1,400 daN. 
8. Stays shall be anchored to the ground through metallic, concrete or wood anchors or anchors made in any other material capable of withstanding the mechanical efforts to which they will be exposed and protected against outside weather conditions, in particular salty environments. 
9. Insulators shall be made in porcelain, glass or other materials of equivalent resistance insulating, weather resistance (in particular resistance to salty environments) and mechanical resistance as porcelain and glass insulators. 
10. Insulators shall be installed fixing them to the support structures or walls by means of threaded mechanisms or cementation with substances that do not damage any of the parts in contact with it and which do not suffer volumetric variations that can impact the insulators or the safety of the installation.  
11. Support structures shall be made in metal, concrete or wood. 
12. Support structures shall be protected against outside weather conditions (in particular against salty environments) either by themselves of by means of protective coverings or treatments (such as galvanizing). 
13. The foundations of support structures shall be adequate to the load supported by the structure and be calculated taking into account the weight of the foundation itself. Article 20. Mechanical calculations 
14. In the mechanical calculations of the elements of LV overhead lines, the following loads shall be taken into account: 

Article 18. Insulators 

Article 19. Support structures 

1.1.        The own weight of the elements, as a vertical load; 

1.2.        Overloads due to wind pressure, as a load perpendicular to the length of the line, unless in those cases where the wind constantly blows in parallel to the direction of the line. The wind overload shall take the following values: 

1.2.1.     On conductors: 50 daN/m²; 

1.2.2.     On flat surfaces: 100 daN/m²; 

1.2.3.     On cylindrical surfaces of support structures: 70 daN/m².  

1. Support structures shall be designed to have a security coefficient between its tensile strength and its maximum tensile strength or breaking stress of at least 2.5 when under the worse loading conditions foreseen (loads, overloads and temperature). 
2. The maximum drag of conductors shall be calculated under the maximum loading conditions foreseen (loads and overloads) at a temperature not lower than 50 ºC. 
3. Support structure shall be calculated for supporting their own load and the loads of the elements there connected, including the stress case where one of the conductors connected breaks. The minimum breaking stress security coefficients for support structures shall be: 

Table  2 – Minimum breaking stress security coefficients for structures of LV overhead lines 

Article 21. Electrical calculations 

1. The maximum current in bare copper conductors in steady operation shall not be higher than the values in the following table: 

Table  3 – Maximum current density for conductors of LV overhead lines 

1. The maximum current in insulated copper conductors in steady operation shall be calculated based on the following base case for open air installations with an ambient temperature of 40 ºC: 

Table  4 – Maximum current in insulated copper conductors in steady operation of LV overhead lines 

1. Correction factors for insulated cables: 

3.1.        In case of insulted conductors directly exposed to solar irradiation, a correction factor of 0.9 shall be applied to all admissible maximum currents to take into account the surface heating of the cable. 

3.2.        In case insulated cables are grouped the following correction factor shall be applied to take into account the deteriorated ventilation (assuming distance between cables, L, longer than a quarter of the diameter of the cables and shorter than a diameter): 

Table  5 – Correction factors for insulated cables in LV overhead lines 

Figure 1 – Scheme of the assumed distances between insulated cables for the 

application of correction factors in LV overhead lines

1. The maximum short-circuit current admissible in insulated LV cables shall depend on the cross section of the conductors and the length of the short-circuit as per the following table, measured in kA: 

Table  6 – Maximum short-circuit current admissible in insulated LV cables by conductor’s cross section and length of the short-circuit 

Article 22. Minimum installation distances 

1. Insulated conductors shall be installed in a way such that the lowest point is at least 2.5 m. over ground level.  
2. Bare conductors shall be installed in a way such that the lowest point is at least 4 m. over ground level. 
3. Conductors shall be installed with minimum separation distances of at least: 

3.1.        0.30 m from the upper side of windows; 

3.2.        0.50 m from the lower side of windows; 

3.3.        0.05 m from metallic elements present in facades, unless specifically protected for that purpose; 

3.4.        0.30 m from the upper side of balconies; and 

3.5.        1.00 m from the lower side of balconies. 

1. The minimum distance between bare conductors and between these and buildings’ walls shall be at least: 

4.1.        0.10 m. for spans of up to 4 m.; 

4.2.        0.15 m. for spans of between 4 and 6 m.; 

4.3.        0.20 m. for spans of between 6 and 30 m.; and 

4.4.        0.30 m. for spans of between 30 and 50 m. 

4.5.        For spans longer than 50 m. the minimum distance shall be obtained with the following formula: 

𝐷 = 0.55 ∙ 𝑠𝑎𝑔 𝑖𝑛 𝑚𝑒𝑡𝑟𝑒𝑠

1. Conductors attached to walls and facades shall have a minimum distance of 0.20 m. between them. 
2. Where a LV overhead lines crosses a MV overhead lines, the LV line shall pass under that of MV at a distance of at least: 

𝑈 +  𝐿1 + 𝐿2

𝑑 = 1.5 +  

100

              Where:

-       U = nominal voltage, in KV, of the MV line; 

-       L1 = Lenth, in m., between the crossing point and the nearest MV line support structure; 

-       L2 = Length, in m., between the crossing point and the nearest LV line support structure. 

1. Where two bare conductor LV overhead lines cross, the minimum distance between them shall be 0.50 m. in general; unless the crossing takes place at a support structure, then the minimum distances set in Point 4 of this Article shall apply. 
2. Where a bare conductor LV overhead line crosses a telecommunications line, the former shall pass above the latter.  The minimum distance between them shall be 0.50 m. 
3. Where a LV overhead line crosses over navigable water, the lowest point of the line shall be at least 1 m. over the maximum height over water of the boats authorized to pass there. 
4. Where a LV overhead line crosses a water, fuel or gas pipe, the minimum distance between them shall be 0.20 m for insulated conductors and 1 m. for bare conductors. Joints in the line or in the pipe shall be at least 1 m. away from the crossing point. 
5. Where a LV overhead line runs parallel to a MV overhead line, the minimum distance between them shall be equal to 1.5 times the height of the highest support structure of any of the lines. Exceptions to this rule are access lines for Generating Stations, transformer substations and distribution transformers. 
6. Where two LV overhead lines run in parallel, the minimum distance between them shall be 

0.50 m in case of insulated conductors and 1 m. in case any of them has bare conductors. 

1. Where LV overhead lines run in parallel to roads or ways, the minimum distance between the road or way and the overhead line shall be 6 m. in case vehicles circulate on the road. In case vehicles do not circulate on the road or way, the minimum distance can be reduced to 5 m. for bare conductors and 4 m. for insulated conductors. 
2. The minimum distance between LV overhead lines and water, fuel and gas pipes shall be 0.20 m and 1 m. from joints. The minimum distance shall be increased to 1 m. in case of important fuel or gas pipes. 

Section 3. Standards for LV underground cables in outdoor areas and public areas 

Article 23. Conductors 

1. LV conductors used in underground installations in outdoor areas and public areas shall be made in copper and be insulated with appropriate polymeric compounds. 
2. LV underground cables shall be protected against corrosion and shall have the mechanical strength required to withstand any effort that they are reasonably expected to suffer. 
3. Cables can be of one or more conductors and be of nominal voltage not lower than 0.6/1 kV. 
4. The cross section of conductors used in LV underground cables shall be adapted to the currents and voltage drops foreseen and in any case not smaller than 6 mm²  
5. The neutral conductor shall have a cross section Equal to that of the phase conductors for cables with two, three or four conductors. 
6. Conductor routing shall be made as straight as possible, observing the minimum curve radium recommended by the manufacturer and, whenever possible, in parallel with building facades, roads, ways and sidewalks. 

Article 24. Installation of underground cables 

1. Underground cables shall be installed: 

1.1.        In public terrain where possible; 

1.2.        In a path as straight as possible, in parallel with the main surrounding buildings’ facades where possible; 

1.3.        With clear indications, at each accessible point, of the hazardous nature of the cable; and 

1.4.        Observing the minimum cable bend radius as set by the manufacturer. 

1. Underground cables can be either: 

2.1.        Directly buried cables; or 

2.2.        Cables in duct. 

1. Directly buried cables: 

3.1.        Shall be buried so that the upper border of the cable is at least 0.60 m. below the surface if under a sidewalk or at least 0.8 m. if under a road. 

3.2.        Lower deepness can be accepted if the cable is adequately equipped with additional mechanic protections. 

3.3.        A layer of at least 5 cm. of sand or material of similar characteristics shall be deposited immediately over the trench and under the cable, free of extraneous bodies. 

3.4.        A layer of at least 10 cm. of sand or material of similar characteristics shall be deposited immediately over the cable, free of extraneous bodies 

3.5.        The sides of the trench shall be stable and not present rockfall risk. 

3.6.        In order to avoid damage due to excavations made by third parties, cables shall be mechanically protected to withstand a point impact of 20 J of energy. The mechanical protection shall cover the plan projection of the cable. 

1. Cables in duct: 

4.1.        Shall be buried so that the upper border of the duct is at least 0.6 m. below the surface if under a sidewalk or at least 0.8 m. if under a road. 

4.2.        Ducts where the cable is installed shall be made in synthetic material, cement and derivatives or in metal subject to withstand the necessary mechanical efforts. 

4.3.        The inner diameter of the duct shall not be less than 1.5 times the diameter of the cable or of the apparent diameter of the set of cables in case several cables are installed in the same duct. 

4.4.        The interior of the duct shall be smooth so as to facilitate the installation and removal of the cables. 

4.5.        No more than one circuit of cables shall be installed per duct. 

4.6.        In case a single single-pole cable is installed in a duct, the duct shall be made in non-ferromagnetic material. 

4.7.        The deployment of the duct shall avoid bend ratios smaller than those recommended by the manufacturer of the cable. 

4.8.        Inspection chambers shall be installed at each end of the cable. Intermediate inspection chambers at least every 40 m.  

1. Where the current to be wheeled is higher than that admissible by a single cable, several conductors per phase are allowed subject to the following requirements:

5.1.        Use conductors of the same material, section and length; and 

5.2.        Cables shall be grouped symmetrically staggered in one or several levels. 

Article 25. Electrical calculations 

1. Electrical calculations shall be made to obtain the electrical parameters, maximum currents, voltage drops and power losses associated to the LV underground cable under all foreseen operation modes in order to avoid overshooting the maximum temperature for the cable. 
2. The maximum current admissible during steady operation shall depend on the maximum temperature the insulation of the cable is able to withstand without deteriorating its electrical, mechanical or chemical properties. Maximum temperatures for cables with dry insulation are those indicated in the following table or as indicated by the manufacturer: 

Table  7 – Maximum temperature for underground cables with dry insulation 

1. Directly buried installations 

3.1.        The maximum current in steady operation shall be determined based on the base installation: dry insulation installation of a single two-pole cable or two single-pole cables in contact, directly buried in all their length in a trench at 0.70 m. deep, in a soil with average thermal resistivity equal to 1 K.m./W., with an average soil temperature at the mentioned depth of 25 ºC and temperature at that deepness of 25 ºC. 

3.2.        The calculation of the maximum current shall be adapted to each particular situation to ensure that the maximum temperature generated by the calculated current is not higher than the one stipulated in Point 2 of this Article. 

3.3.        Maximum steady operation current (A.) for the base installation with copper conductor as per standard IEC 60364-5-52: 

Table  8 – Maximum steady operation current by type of LV directly buried underground cable 

*Including the neutral conductor, if any

3.3.1.     In the case of two single-pole cables, the maximum current of the above table for the triplet of single-pole cables table shall be increased by a corrective factor of 1.225. 

3.3.2.     In the case of a 2-pole cable, the maximum current of the above table for the 3-pole cable shall be increased by a corrective factor of 1.225. 

1. Correction factors for buried cables  

4.1.        Correction for soil temperature 

4.1.1.     Where the average temperature of the soil is different than 25 ºC, the following correction factor F shall be applied to direct buried cables depending on the maximum temperature for the conductor (Өs) as per IEC 60364-5-52: 

Table  9 – Correction factor F for direct buried LV cables depending on the maximum temperature for the conductor and the soil temperature 

4.1.2.     The correction factor F for temperatures other than those in the table shall be: 

𝜃_𝑠 − 𝜃_𝑡

𝐹 =  

𝜃_𝑠 − 25

4.2.        Correction for soil thermal resistivity 

4.2.1.     Where the thermal resistivity of the soil is different than 1 K.m./W., the following correction factor shall be applied as per IEC 60364-5-52: 

Table  10 – Correction factor for soil thermal resistivity for LV directly buried underground cables 

4.3.        Correction for composition of the cable 

4.3.1.     Where there are more than one 3-pole cable or more than one triplet of single pole cables the following correction factors shall be applied depending on the number of those 3-pole cables or triplets and the distances between them, as per IEC 60364-5-52: 

Table  11 – Correction factors for composition of the cable in directly buried LV underground cables 

Figure 2 – Scheme of distribution of directly buried LV underground cables 

4.4.        Correction for depth different than 0.70 m. 

4.4.1.     Where there cables are buried at depths different than 0.70 m. the following correction factors shall be applied as per IEC 60364-5-52: 

Table  12 – Correction factors for depth of directly buried cables different than 0.70 m. 

1. Cables in duct 

5.1.        The maximum current in steady operation for LV underground cables installed in ducts shall be calculated based on the maximum current for directly buried cables corrected by the following factors: 

5.1.1.     In case a line has a 3-pole cable or a triplet of single-pole cables inside the same duct, a correction factor of 0.8 shall be applied; 

5.1.2.     In case a line has four single-pole cables placed in four separate ducts, a correction factor of 0.9 shall be applied; 

5.1.3.     Where the length of the section of cable installed in duct is not longer than 15 m. and the duct is filled with special agglomerates, no correction factor shall be required and the maximum currents for directly buried cables shall apply. 

5.1.4.     Other cases and cable configuration shall be analyzed on a case per case basis so that the maximum temperature in the cable does not overshoot the maximum temperature by type of insulator defined in Point 2 of this Article. 

1. Open air installations 

6.1.        The maximum current in steady operation shall be determined based on the base installation: dry insulation installation composed of a single 3-pole or 4-pole cable or triplet of single-pole cables in contact, deployed in a way that allows good airflow, protected from the sun and with ambient air temperature of 40 ºC. 

6.2.        The calculation of the maximum current shall be adapted to each particular situation to ensure that the maximum temperature generated by the calculated current is not higher than the one stipulated in Point 2 of this Article. 

6.3.        Maximum steady operation current (A.) for the base installation with copper conductor as per IEC 60364-5-52: 

Table  13 – Maximum steady operation current for the base installation with copper in open air LV cable installation 

*Including the neutral conductor, if any

6.4.        Correction factors for open air installations  

6.4.1.     Correction for air temperature 

a)                      Where the average temperature of the air is different than 40 ºC, the following correction factor F shall be applied to direct buried cables depending on the maximum temperature for the conductor (Өs), as per IEC 60364-5-52: 

Table  14 – Correction factors for air temperature for open air LV cable installations 

b)                      The correction factor F for temperatures other than those in the table shall be: 

𝜃_𝑠 − 𝜃_𝑎

𝐹 =  

𝜃_𝑠 − 40

6.4.2.     Correction for deficient ventilation 

Where the circulation of air is not free, the temperature of the ambient air surrounding the conductors increases and therefore the maximum current shall be reduced by the correction factors for air temperature. The correction factor selected shall vary in each case depending on the increase of air temperature suffered, but as reference it may be approximated to an increase of 15 ºC. 

6.4.3.     Correction for different cable installation configurations 

The following tables summarise the correction factors to be used in case of different installation configuration for groups of several single-pole or multi-pole cable circuits depending on the type of installation and the number of circuits (for a standard distance between trays of 300 mm in non-perforated trays and 225 mm between perforated trays)^[3], as per IEC 60364-5-52: 

a)                      Correction factor for groups of single-pole cables 

Table  15 – Correction factor for groups of single-pole LV cables in open air installations

b)                      Correction factor for groups of 3-pole cables 

Table  16 – Correction factors for groups of 3-pole LV cables in open air installations 

Article 26. Minimum installation distances 

1. Where a LV underground cable crosses another electrical cable, the one with lower voltage level shall be placed above those with higher voltage. The minimum distance between a LV underground cable and another electrical cable shall be 0.25 m. with MV cables and 0.10 with other LV cables. The distance between the crossing point and junctions in any of the cables that cross shall be at least 1 m. Whenever these minimum distances cannot be observed, cables shall be installed within ducts. 
2. Where a LV underground cable crosses a road or way, cables shall be installed within protective pipes or ducts, covered in concrete in all their length under the road or way and placed at a minimum depth of 0.80 m. under ground level. Whenever possible, the crossing shall take place perpendicular to the axis of the road or way.  
3. Where a LV underground cable crosses a telecommunication cable, the minimum separation between them shall be 0.20 m. The minimum distance between the crossing point and joints in any of the cables shall be 1 m. Where these minimum distances cannot be observed, the most recently installed cable shall be installed in a protective duct. 
4. Where a LV underground cable crosses water, fuel or gas pipes the minimum distance between them shall be 0.20 m. The minimum distance between the crossing point and joints in the cable or the pipes shall be 1 m. Whenever possible the electricity cable shall be placed above water pipes. Where these minimum distances cannot be observed, the most recently installed cable or pipe shall be installed in a protective duct. 
5. Whenever possible, electric cables shall be installed above sewerage installations. It shall not be possible to install electric cables within sewage installations. 
6. Where a LV underground cable crosses a fuel tank, the cable shall be installed in a protective duct for at least 1.5 m. before and 1.5 m. after the tank and at a distance of at least 0.20 m. 
7. LV underground cables can be installed parallel to other LV or MV cables subject keeping a distance of at least 0.10 m. with LV cables and at least 0.25 m. with MV cables. Where these minimum distances cannot be observed, the most recently installed cable shall be installed in a protective duct. In case all LV cables in parallel belong to the same owner, they can be installed at distances lower than the minimum ones above presented and even in contact. 
8. The minimum distance between a LV underground cable and a telecommunications cable shall be 0.20 m. Where this minimum distance cannot be observed, the most recently installed cable shall be installed in a protective duct.  
9. The minimum distance between a LV underground cable and a water, fuel or gas pipe shall be 0.20 m. In case of high pressure gas pipes, the minimum distance shall be at least 0.40 m. The minimum distance between the joints of the underground cable and those of the pipe shall be at least 1 m. Where these minimum distances cannot be observed, the most recently installed cable or pipe shall be installed in a protective duct.  

Section 4. Standards for LV switchgear and controlgear 

Article 27. Requirements for LV switchgear and controlgear 

1. Switching devices and control devices installed in the LV network in outdoor areas and public areas shall comply with the requirements of IEC 61439. 
2. Switching devices shall be installed as close as possible to support structures and as close as possible to the connection point of customer supplies as possible. 
3. Switching devices shall be at least of class IP 65 when installed in outdoor Electrical Installations (outdoor areas and public areas). 
4. LV switchgear and controlgear shall be coordinated with the MV switchgear and controlgear to grant adequate protection system coordination (trip current and trip times). 

CHAPTER IV. STANDARDS FOR LV ELECTRICAL 

INSTALLATIONS (IN-HOUSE AREAS) 

Section 1. General Specifications 

Article 28. Selection of electrical equipment 

Every item of electrical equipment selected shall have suitable characteristics appropriate to the values and conditions on which the design of the Electrical Installation is based and shall, in particular, fulfil the following requirements: 

1. Electrical equipment shall be suitable with respect to the maximum steady voltage (root mean square value for alternative current systems) likely to be applied, as well as overvoltages likely to occur. 
2. All electrical equipment shall be selected with respect to the maximum steady current which it has to carry in normal service, and with respect to the current likely to be carried in abnormal conditions and the period during which it may be expected to flow.  
3. If frequency has an influence on the characteristic of electrical equipment, the rated frequency of the equipment shall correspond to the frequency likely to occur in the circuit. 
4. All electrical equipment, which is selected on the basis of its power characteristic, shall be suitable for the duty demanded of the equipment, taking into account the load factor and the normal service conditions. 
5. All electrical equipment shall be selected so as to withstand safely the stresses and the environmental conditions characteristic of its location and to which it may be exposed. If, however, an item of equipment does not have by design the properties corresponding to its location, it may be used on condition that adequate additional protection is provided as part of the completed Electrical Installation.  
6. All electrical equipment shall be selected so that it will not cause harmful effects on other equipment, or impair the supply during normal service including switching operations. In this context, the factors which can have an influence include, e.g.: 

6.1.        Power factor; 

6.2.        Inrush current; 6.3.      Asymmetrical load; and 

           6.4.     Harmonics. 

Article 29. Erection and initial verification of Electrical Installations 

1. For the erection of the Electrical Installation, good workmanship by suitably electricians licensed by the MEA and the use of proper materials shall be provided for. 
2. The characteristics of the electrical equipment, as determined in accordance with Article 28 shall not be impaired in the process of erection. 
3. Conductors shall be identified in accordance with IEC 60445 or any standard that replaces it 
4. Connection between conductors and between conductors and other electrical equipment shall be made in such a way that safe and reliable contact is ensured. 
5. All electrical equipment shall be installed in such a manner that the design cooling conditions are not impaired. 
6. All electrical equipment likely to cause high temperature or electric arcs shall be placed or guarded so as to eliminate the risk of ignition of flammable materials. Where the temperature of any exposed parts of electrical equipment is likely to cause injury to persons, those parts shall be so located or guarded as to prevent accidental contact therewith. 
7. Electrical installations shall be tested and inspected before being placed in service and after important modification to verify proper execution of the work in accordance with the applicable standards. 

Section 2. Selection and Erection of Electrical Equipment 

Article 30. Common rules 

1. This section deals with the selection of equipment and its erection. It shall provide compliance with the measures of protection for safety, the requirements for proper functioning for intended use of the installation, and the requirements appropriate to the external influences foreseen. Every item of equipment shall be selected and erected so as to allow compliance with the rules stated in the following clauses of this section and the relevant rules in other sections of this document. 
2. Equipment shall be selected for the design current which it has to carry in normal steady operation. 
3. Equipment shall also be capable of carrying the currents likely to flow in abnormal conditions for such periods of time as are determinate by the characteristic of the protective devices. 
4. If frequency has an influence on the characteristics of equipment, the rated frequency of the equipment shall correspond to the frequency of the current in the circuit concerned. 
5. Equipment selected for its power characteristics shall be suitable for normal operational conditions taking account of the load factor 
6. Unless other suitable precautions are taken during erection, all equipment shall be selected so that it will not cause harmful effects on other equipment nor impair the supply during normal service, including switching operations. 
7. Electrical equipment shall be selected and erected in accordance with the requirements of tab 51A  of IEC 60364 5-51 which indicates the characteristics of equipment necessary according to the external influences to which the equipment may be subjected. 
8. Equipment characteristic shall be determined either by a degree of protection or by conformity of tests. 
9. If the equipment does not, by its construction, have the characteristic relevant to the external influences of its location, it may nevertheless by used on condition that it is provided with appropriate additional protection in the erection of the installation, Such protection shall not adversely affect the operation of the equipment thus protected. 
10. When different external influences occur simultaneously, they may have independent or mutual effect and the degree of protection shall be provided accordingly. 
11. All equipment, including wiring, shall be arranged so as to facilitate its operation, inspection and maintenance and access to its connections. Such facilities shall not be significantly impaired by mounting equipment in enclosure or compartments. 
12. Labels or other suitable means of identification shall be provided to indicate the purpose of switchgear and controlgear.. 
13. Where the functioning of switchgear and controlgear cannot be observed by the operator and where this might cause a danger, a suitable indicator, complying where applicable with IEC 60073 and IEC 60447, shall be fixed in a position visible to the operator. 
14. Wiring systems shall be arranged or marked so that they can be identified for inspection, testing, repairs or alteration of the installation. 
15. The identification of separate neutral and proactive conductors shall comply with IEC 60445 or the standard that replaces it. 
16. PEN conductors, when insulated, shall be marked by one of the following methods: 

16.1.       Green or green with yellow stripes throughout their length with, in addition, light blue marking at the terminations.  

1. The protective devices shall be arranged and identified so that circuits protected may be easily recognized. 
2. Where appropriate diagrams, charts or tables in accordance with IEC 81346-1 shall be provided indicating in particular: 

18.1.       The type and composition of circuits (points of utilization served, number and size of conductors, type of wiring); 

18.2.       The characteristics necessary for the identification of the devices performing the functions of protection, insulation and switching and their location. 

1. Equipment shall be selected and erected so as to avoid any harmful influence between the Electrical Installation and any non-electrical installation. 
2. Equipment not provided with a backplate shall not be mounted on a building surface unless the following required are satisfied: 

20.1.       A voltage transfer to the building surface is prevented; and 

20.2.       Fire segregation is provided between the equipment and a combustible building surface;  

1. If the building surface is non-metallic and non-combustible, no additional measures are required. If not, these requirement may be satisfied by one of the following measures: 

21.1.       If the building surface is metallic, it shall be bonded to the protective conductor (PE) or to the equipotential bonding conductor of the installation, in accordance with IEC 60364-4-41 and IEC 60364-5-54. 

21.2.       If the building surface is combustible, the equipment shall be separated from it by a suitable intermediate layer of insulating material having a flammability rating of FH1 according to IEC 60707. 

1. Where equipment carrying currents of different types or at different voltages is grouped on a common assembly (such as a switchboard, a cubicle or a control desk or box), all the equipment belonging to any one type of current or any one voltage shall be effectively segregated wherever necessary to avoid mutual detrimental influence. 
2. The immunity levels of equipment shall take into account the electromagnetic influences that can occur connected and erected as for normal use, and also take into account the intended level of continuity of service necessary for the application. 
3. Equipment shall be chosen with sufficiently low emission levels so that it cannot cause electromagnetic interference by electrical conduction or propagation on the air with other electrical equipment inside or outside the building. If necessary, means of mitigation shall be installed to minimize the emission. 
4. Electrical wiring 

Article 31. Wiring systems 

1.1.        Electrical wiring should be done by a MEA approved and licensed  electrician. 

1.2.        Wiring colour code: 

1.2.1.     In single phase wiring, the phase wire must be brown, neutral must be blue, and the earth must be green with yellow stripes. 

1.2.2.     In three phase wiring, phase 1 must be black, phase 2 must be brown, phase 3 must be grey, neutral must be blue, and the earth must be green with  yellow stripes. 

1.2.3.     In any case, for earth wire anything other than green with yellow stripes and for neutral anything other than blue must not be used. 

1.2.4.     As a temporary measure, for as long as the MEA authorizes it, at sites where three phase wiring is required, and the prescribed colour of wire is not available, the end of each wire should be sleeved with the respective phase colour. 

1.3.        In three-phase wiring the load should be balanced among the three phases. 

1.4.        Phase wires shall be dimensioned to withstand in normal operation the aggregated current of the loads there connected. The licensed engineer or electrician (whereas applicable) shall certify dimensions of the cables. 

1.5.        The typical tripping current for earth leakage circuit breaker in households or residential buildings shall be 30 milli Amps. Nevertheless, it shall be possible to set the tripping point to different current levels where deemed necessary. The circuit breaker shall be 240 V rated voltage and 30-63 Amps rated current, 2 pole current operated ELCB. In case of three phase circuits, for a tripping current of 30 milli Amps, the circuit breaker shall be 30-63 A rated current, 380-400 rated voltage and 4 pole current operated. The rated current should not exceed the prescribed level and the tripping current must not exceed 30 milli Amps. ELCB with tripping currents less than 30mA can be accepted where it is deemed necessary.  Exception to this rule are ELCB of residual current devices installed in central alternative current systems of buildings which may have trigger current higher than 30 milli Amps but in any case not exceeding 100 milli Amps. 

1.6.        For a light circuit, if the wire size is 1.5 mm²a single circuit must not exceed a total of 1000W. 

1.7.        Not more than one phase must be used in a single box 

1.8.        Wiring must be done in a conduit or trunking .  

1.9.        Machineries installed in commercial and industrial electrical installations must be connected by using appropriate cable size and through starter or main switch. Such starter switch must be installed close to the machinery in an easy to operate manner. 

1.10.       Water prone areas should have water proof switches and socket outlets. if normal switches & sockets are is used, it must be mounted where water will not reach it. 

1.11.       Any type of socket can be installed but at least one socket per room shall be of Type G BS-1363. 

1.12.       Insulation resistance of an installation (phase-neutral, phase-earth and neutral-earth ) should have minimum of 1 mega ohms.  

1.13.       In case a resident needs to connect a backup/emergency generator apart from the existing service provider’s supply a change-over switch must be introduced. The change-over switch must be able to disconnect the phase/live conductors and as well as the neutral, and must present a rating adequate to the required load. 

1.14.       All new electrical installations shall be tested and approved by either licensed engineers or electricians (according to the case) for such purposes, before being energized and will be accountable if any fault arises from the distribution board wiring. 2.Distribution Board 

2.1.        The DB shall be protected by a cover with degree of protection of at least IP 30 for indoor case and IP 65 for outdoor case. 

2.2.        DB shall be fixed at a height between 1.5 to 1.8m. However in the case of DBs with multiple rows, the lowest point shall not be less than 1.5m 

2.3.        The Distribution Board shall include at least the following switching and control devices: 

2.3.1.     A Power Control Switch that cuts the power supply in case the power withdrawn overshoots the contracted capacity. 

2.3.2.     A main switch circuit breaker, omnipolar, with capability for manual operation and equipped with protection against overloading and short-circuits. This circuit breaker shall be independent from the Power Control Switch. 

2.3.3.     A residual current device, which shall protect the Electrical Installation against indirect contacts in any of the circuits by automatically disconnecting it from the power supply. 

2.3.4.     Individual omnipolar circuit breaker to protect each of the circuits that form the Electrical Installation in-house. 

2.3.5.     Any specific control device that may be required for the application of the selected electricity tariff to the Electrical Installation. 

2.4.        Optionally, the DB may also include a device for protection against overvoltage. 

2.5.        Every socket must be wired to the DB with a phase wire along with the earth and neutral wire. At the DB, the circuit breaker must be appropriately sized for the socket and it should not be higher than what is required for the socket 

In a building the earth wire connected to ground should be appropriately thick to allow wheeling the foreseen short-circuit current in the electrical installation, including lightning discharges. The main earth wire should originate from the distribution board (DB) or the main switch via the assigned site. The earth wire should be connected solidly connected to the earth rod.  Inspection chamber shall be provided for testing of main earthing.  

3. Selection and erection in relation to external influences 

3.1.        The wiring system shall be selected and erected so as to be suitable for the highest local ambient temperature. 

3.2.        Wiring system components including cables and wiring accessories shall be installed or handled only at temperature within the limits stated in the relevant product specification or as given by the manufacturer. 

3.3.        In order to avoid the effects of heat from external sources one of the following methods or an equally method shall be used to protect wiring systems: 

3.3.1.     Shielding;

3.3.2.     Placing sufficiently far from the sources of heat; 

3.3.3.     Selecting a system with due regard for the additional temperature rise which may occur; or 

3.3.4.     Local reinforcement or substitution of insulating material. 

3.4.        The wiring system shall be selected and erected so that no damage is caused by ingress of water. The completed wiring system shall comply with the IP degree of protection relevant to the particular location. 

3.5.        Where water may collect or condensation may form in wiring system, provision shall be made for its escape. 

3.6.        Where wiring system may be subjected to waves, protection against mechanical damage shall be afforded.  

3.7.        Wiring system shall be selected and erected so as to minimize the danger arising from the ingress of solid foreign bodies. The completed wiring system shall comply with the IP degree of protection relevant to the particular location. 

3.8.        In a location where dust in significant quantity is present, additional precaution shall be taken to prevent the accumulation of dust or other substances in quantities which could adversely affect the heat dissipation from the wiring system. 

3.9.        Where the presence of corrosive or pollution substances, including water, is likely to give rise to corrosion or deterioration, parts of the wiring system likely to be affected shall be suitably protected or manufactured form a material resistant to such substances. 

3.10.       Dissimilar metals liable to initiate electrolytic action shall not be placed in contact with each other, unless special arrangements are made to avoid the consequences of such contacts. 

3.11.       Material liable to cause mutual or individual deterioration or hazardous degradation shall not be placed in contact with each other. 

3.12.       The wiring system shall be selected and erected so as to minimize the damage arising from mechanical stress, e.g. by impact, penetration or compression. 

3.13.       In installations fixed to a structure or equipment, fixation shall be afforded by:

3.13.1.  The mechanical characteristics of the wiring system; or 

3.13.2.  The location selected; or 

3.13.3.  The provision of additional local or general mechanical protection; or 

3.13.4.  By any combination of the above. 

3.14.       The wiring system supported by or fixed to structure of equipment subject to vibration of medium severity or high severity shall be suitable for such conditions, particularly where cables and cable connection are concerned. 

3.15.       The wiring system shall be selected and erected so as to prevent during installation, use or maintenance, damage to sheath and insulation of cables and conductor and their terminations. 

3.16.       When buried in the structure, conduits or cable ducting system shall be completely erected for each circuit before any insulated conductor or cable is drawn in. 

3.17.       The radius of every bend in a wiring system shall comply with the minimum bending radius recommended by the cable or wire manufacturer. 

3.18.       Where the conductors and cables are not supported continuously by their supports or due to the method of the installation, they shall be supported by suitable means at appropriate intervals in such a manner that the conductors and cables do not suffer damage by their own weight. 

3.19.       Where a permanent tensile stress is applied to the wiring system (e.g. by its own weight in vertical runs) a suitable type of cable or conductor with appropriate crosssectional areas and method of mounting shall be selected, in such a manner that the conductors and cables do not suffer damage by their own weight. 

3.20.       Wiring system intended for the drawing in or out of conductors or cables shall have adequate means of access to allow this operation. 

3.21.       Wiring system buried in floors shall be sufficiently protected to prevent damage caused by the intended use of the floor. 

3.22.       Wiring system which are rigidly fixed and buried in the walls shall be run horizontally or vertically or parallel to the room edges. 

3.23.       Wiring system shall be installed so that excessive tensile stress to the conductors and connections is avoided. 

3.24.       Flexible wiring system shall be installed so that excessive tensile stress to the conductors and connection is avoided. 

3.25.       Where the conditions experienced or expected constitute a hazard the wiring system shall be selected accordingly or special protective measures shall be adopted. 

3.26.       Where significant solar radiation is experienced or expected, a wiring system suitable for the conditions shall be selected and erected or adequate shielding shall be provided. 

3.27.       The wiring system shall be selected and erected with due regard to the seismic hazards of the location of the installation. 

3.28.       Where the seismic hazards experienced are low severity or higher, particular attention shall be paid to the following: 

3.28.1.  The fixing of wiring system to the building structure; and 

3.28.2.  The connections between the fixed wiring and all items of essential equipment, 

e.g. safety services, shall be selected for their flexible quality. 

3.29.       Where the risk due to structural movement exists, the cable support and protection system employed shall be capable of permitting relative movement so that conductors and cables are not subjects to excessive mechanical stress. 

3.30.       For flexible or unstable structures, flexible wiring system shall be used. 

1. Electrical connections 

4.1.        Connections between conductors and between conductors and other equipment shall provide durable electrical continuity and adequate mechanical strength and protection. 

4.2.        The selection of the means of connection shall take account as appropriate of: 

4.2.1.     the material of the conductor and its insulation; 

4.2.2.     the number and shape of the wires forming the conductor; 

4.2.3.     the cross-sectional area of the conductor; and 

4.2.4.     the number of conductors to be connected together. 

4.3.        All connections shall be accessible for inspection, testing and maintenance, except for the following: 

4.3.1.     Joints in buried cables; 

4.3.2.     Compound-filled or encapsulated joints; 

4.3.3.     Connections between a cold tail and the heating element as in ceiling heating, floor heating and trace heating system. 

4.4.        Where necessary, precautions shall be taken so that the temperature attained by connections in normal service shall not impair the effectiveness of the insulation of conductors connected to them or supporting them. 

1. Selection and erection to minimize the spread of fire 

5.1.        The wiring system shall be installed so that the general building structural performance and fire safety are not reduced. 

5.2.        Where a wiring system passes through elements of building construction such as floors, walls, roofs, ceilings, partitions or cavity barriers, the opening remaining after passage of the wiring system shall be sealed according to the degree of fire resistance (if any) prescribed for the respective element of building construction before penetration. 

5.3.        Wiring systems such as conduits, cable ducting, cable trunking, busbars or busbar trunking system which penetrate elements of building construction having specified fire resistance shall be internally selected to the degree of fire resistance of the respective element before penetration as well as being externally sealed as required by Point 5.2 of this Article. 

5.4.        No wiring system shall penetrate an element of building construction which is intended to be load bearing unless the integrity of the load bearing element can be assured after such penetration. 

5.5.        Sealing arrangements shall resist external influences to the same degree as the wiring system with which they are used and in addition they shall all of the following requirements: 

5.5.1.     They shall be resistant to the products of combustion to the same extent as the elements of building construction which have been penetrated; 

5.5.2.     They shall provide the same degree of protection from water penetration as that required for the building construction element in which they have been installed; 

5.5.3.     The seal and the wiring system shall be protected from dripping water which may travel along the wiring system or which may otherwise collect around the seal unless the materials used in the seal are all resistant to moisture when finally assembled for use. 

5.6.        During erection of a wiring system temporary arrangements may be required. 

5.7.        During alteration work, sealing should be reinstated as quickly as possible. 

5.8.        The sealing arrangements shall be inspected to verify that they conform to the erection instruction associated with the Integrated Circuit Type Test for the product concerned. 

5.9.        Band I and Band II voltage circuits, as per IEC 60449, shall not be contained in the same wiring system unless every cable is insulated for the highest voltage present or one of the following methods is adopted: 

5.9.1.     Each conductor of a multi-core cable is insulated for the highest voltage present in the cable; or  

5.9.2.     The cables are insulated for their system voltage and installed in separate compartment of a cable ducting or cable trunking system; or 

5.9.3.     A separate conduit system is employed. 

5.10.       Wiring systems shall not be installed in the vicinity of service which produce heat, smoke or fumes likely to be detrimental to the wiring, unless it is protected from harmful effects by shielding arranged so as not to affect the dissipation of heat from the wiring. 

5.11.       Where a wiring system is routed below services liable to cause condensation (such as water, steam or gas services), precautions shall be taken to protect the wiring system from deleterious effects). 

5.12.       Where electrical services are to be installed in proximity to non-electrical services they shall be so arranged that any foreseeable operation carried out on the other services will not cause damage to the electrical services or the converse. 

1. Selection and erection in relation to maintainability, including cleaning 

6.1.        The knowledge and experience of the person or persons likely to carry out the maintenance shall be taken into account in the selection and erection of the wiring system. 

6.2.        Where it is necessary to remove any protective measure in order to carry out maintenance, provision shall be made so that the protective measure can be reinstated without reduction of the degree of protection originally intended. 

6.3.        Provision shall be made for safe and adequate access to all parts of the wiring system which may require maintenance. 

Article 32. Insulation, switching and control devices 

1. Every Electrical Installation for residential use at LV shall be equipped with at least:  

1.1.        A Power Control Switch (PCS): 

1.1.1.     Capable and configured to disconnect the Electrical Installation main supply in case the power demanded is higher than the power contracted (and for which the PCS is configured). 

1.1.2.     The PCS shall be installed at the distribution board serving the Electrical Installation. 

1.2.        A main switch circuit breaker shall be selected to be able to cut the aggregated current of the group of Electrical Installation supplied from it in case of short-circuit, and in any case at least 4.5k A. 

1.3.        A residual current protective device: 

1.3.1.     Residual current devices in direct current system shall be specially designed for detection of direct current residual currents, and to break circuit currents under normal conditions and fault conditions. 

1.3.2.     Residual current protective devices shall ensure the disconnection of all live conductors in the circuit protected.  

1.3.3.     No protective conductor shall pass through the magnetic circuit of a residual current protective device. 

1.3.4.     Residual current protective devices shall be so selected, and the electrical circuits so subdivided, that any earth-leakage current which may be expected to occur during normal operation of the connected lead(s) will be unlikely to cause unnecessary tripping of the device. 

1.3.5.     The use of a residual current protective device associated with circuit not having a protective conductor, even if the rated operating residual current does not exceed 30 mA, shall not be considered as a measure sufficient for protection against indirect contact. 

1.3.6.     The use of residual current protective devices with an auxiliary source not operating automatically in the case of failure of the auxiliary source is permitted only if one of two following conditions is fulfilled:  

1.3.6.1.        Protection against indirect contact is ensured even in the case of failure of the auxiliary supply; 

1.3.6.2.        The devices are installed in installation operated, tested and inspected by instructed person or skilled persons. 

Article 33. Earthing arrangements and protective conductors 

1. The performance of the earthing arrangements shall be adapted to the safety and functional requirements of the Electrical Installation. 
2. The selection and erection of the equipment of the earthing arrangements shall be such that: 

2.1.        The  value of earthing resistance is in accordance with protective and functional requirements of the installation and expected to be continuously effective; 

2.2.        Earth-fault currents and earth-leakage currents can be carried without danger, particularly from thermal, thermo-mechanical and electro-mechanical stresses; and 

2.3.        It is adequately robust or against or has additional mechanical protection appropriate to the assessed condition of external influences. 

1. Precautions shall be taken against the risk of damage to other metallic parts through electrolysis.
2. Earth electrodes for earthing Electrical Installations 

4.1.        The following types of earth electrodes may be used: 

4.1.1.     Earth rods or pipes; 

4.1.2.     Earth tapes or wires; 

4.1.3.     Earth plates; 

4.1.4.     Earth electrodes embedded in foundation; 

4.1.5.     Metallic reinforcement of concrete 

4.1.6.     Metallic water-pipe system  

4.1.7.     Other suitable underground structures 

4.2.        The type and embedded depth of earth electrodes shall be such that soil drying and freezing will not increase the earth resistance of the earth electrodes above the required value. 

4.3.        The materials used and the construction of the earth electrodes shall be such as to withstand mechanical damage due to corrosion. 

4.4.        The design of the earthing arrangements shall take account of possible increase in earth resistance of earth electrodes due to corrosion. 

4.5.        Metallic water-pipe system may be used as earth electrodes provided that the consent of the distributor of the water is obtained and that suitable arrangements exist for the user of the Electrical Installation to be warned of any proposed changes in the waterpipe system. 

4.6.        Metallic pipe system of service other than that mentioned in Point 4.5 as this concerns only the water service, (e.g. for flammable liquids or gases, heating system, etc.) shall not be used as earth electrodes for protective purposes. 

4.7.        Lead sheaths and other metallic covering of cables not liable to deterioration through excessive corrosion may be used as earth electrodes provided the consent of the owner of the cables is obtained and suitable arrangements exist for the user of the Electrical Installation to be warned of any proposed changes to the cable that may affect its suitability as an earth electrode. 

1. The connection of an earthing system to an earth electrode shall be soundly made and electrically satisfactory. Where a clamp is used, it shall not damage the electrode (e.g. a pipe) of the earthing conductor. 
2. In every installation, a main earthing terminal or bar shall be provided and the following conductors shall be connected to it: 6.1.Earthing conductors; 

6.2.        Protective conductors; 

6.3.        Main equipotential bonding conductors; and 

6.4.        Functional earthing conductors, if required. 

1. Means shall be provided in an accessible position for disconnecting the earthing conductor. Such means may conveniently be combined with the main earthing terminal or bar, to permit measurement of the resistance of the earthing arrangements. This joint shall be disconnectable only by means of a tool, shall be mechanically strong, and ensure the maintenance of electrical continuity. 
2. The cross-sectional area of every protective conductor which does not form part of the supply or cable enclosure shall be , in any case, not less than: 

8.1.        2.5 mm²if mechanical protection is provided; or 

8.2.        4 mm²if mechanical protection is not provided. 

1. Protective conductors may comprise: 

9.1.        Conductors in multi-core cables; 

9.2.        Insulated or bare conductors in a common enclosure with live conductors; 

9.3.        Fixed bare or insulate conductors; 

9.4.        Metal covering, for example, the sheaths, screans and armouring of certain cables; 

9.5.        Metal conduits or other metal enclosures for conductors; and 

9.6.        Certain extraneous conductive parts. 

1. Protective conductors shall be suitable protected against mechanical and chemical deterioration and electrodynamic forces. 
2. Joints of protective conductors shall be accessible for inspection and testing except in compound-filled or encapsulated joints. 
3. No switching devices shall be inserted in the protective conductors, but joints can be disconnected for test purposes by use of a tool. 
4. Where monitoring of earth-continuity is used, the operating coils shall not be inserted in protective conductors. 
5. Where overcurrent protective devices are used for protection against Electric Shock, the incorporation of the protective conductor in the same wiring system as the live conductors or in their immediate proximity is strongly recommended. 
6. An auxiliary earth electrode shall be provided electrically independent of all other earthed metal, for example, constructional metalwork, pipes, or metal-sheathed cables. This requirement is considered to be fulfilled if the auxiliary earth electrode is installed at specified distance from all other earthed metal- 
7. The earthing conductor leading to the auxiliary earth electrode shall be insulated to avoid contact with the protective conductor or any of the parts connected thereto or extraneous conductive parts which are, or may be, in contact with them. 
8. The protective conductor shall be connected only to the exposed conductive parts of those items of electrical equipment whose supply will be interrupted in the event of the protective device operating under fault conditions. 
9. Earthing arrangements for functional purposes shall be provided to ensure correct operation of equipment or to permit reliable and proper functioning of the installation.
10. In TN system, for cables in fixed installation having a cross-sectional area not less than 10 mm²for both copper and aluminium, a single conductor may serve both as protective conductor and neutral conductor, provided that the part of the installation concerned is not protected by a residual current-operated device. 
11. The minimum cross-sectional area of a PEN conductor may be 4 mm2, provided that the cable is of a concentric type conforming to IEC standard and that duplicate continuity connection exist at all joins termination in the run of the concentric conductors. 
12. The PEN conductors shall be insulated for the highest voltage to which it may be subject to avoid stray currents. 
13. If from any point of the installation the neutral and protective function are provided by separate conductors, it is inadmissible to connect these conductors to each other from that point. At the point of separation, separate terminal or bars shall be provided for the protective and neutral conductors. The PEN conductor shall be connected to the terminal or bar intended for the protective conductor. 
14. Main equipotential bonding conductors shall have cross-sectional areas not less than half the cross-sectional area of the largest protective conductor of the installation, subject to a minimum of 6 mm². However, the cross-sectional area need not exceed 25 mm²if the bonding conductor is of copper or a cross-sectional area affording equivalent current-carrying capacity in other metals. 
15. A supplementary equipotential bonding conductor connecting two exposed conductive parts may have a cross-sectional area not less than of the smaller protective conductor connected to the exposed conductive parts. 
16. A supplementary equipotential boning conductor connecting exposed conductive parts to extraneous conductive parts may have a cross-sectional are not less than the cross sectional area of the corresponding protective conductor. 
17. Supplementary equipotential bonding may be extraneous conductive parts of a permanent nature, such as structural metalwork, or by supplementary conductors, or by a combination of these. 
18. Where water pipes of building are used for earthing or as protective conductors, the water meter shall be bonded across and the bonding conductor shall be of appropriate crosssectional area according to its use as a protective conductor, equipotential bonding conductor or functional earthing conductor. 

CHAPTER V. STANDARDS FOR MV ELECTRICAL 

INSTALLATIONS (OUTDOOR AND PUBLIC AREAS AND 

PRIVATE AREAS) 

Section 1. Standards for MV Overhead Lines 

Article 34. Standard voltage levels 

1. Any voltage level higher than 1 kV and equal or lower than 35 kV (phase to phase) shall be considered MV. Out of all the possible voltage levels, the preferred nominal system voltage levels for overhead lines in outdoor areas and public areas in the Republic of Maldives are 6 kV and 11 kV (phase to phase). 
2. Equipment in MV Electrical Installations shall be able to withstand the following maximum voltage without deterioration as per IEC 60183: 

Table  17 – Maximum voltage levels for equipment in MV Electrical Installations 

1. Electrical Installations in private areas may present any voltage level as long as the adequate voltage level conversion systems are installed where those installations are connected to the Distribution Network.  
2. All MV overhead lines shall use copper conductors of cross section no lower than 10 mm². 
3. Connection between conductors shall withstand, without breakage or slippage, at least 95% of the maximum breaking stress of the conductors linked. 
4. It is forbidden to connect conductors through welding techniques. 
5. Fittings are those mechanic elements that are used for fixing insulators to the conductors and to the support structures and the elements installed for the electrical protection of insulators. 
6. Separators, vibration dampers and other accessory elements shall be considered accessories.
7. All fittings and accessories installed shall be designed to be compatible with the electrical and mechanical requirements imposed on the line. 
8. All fittings that shall be able to withstand the weight of a person shall withstand a concentrated load of at least 1.5 kN. 
9. All fittings and accessories installed shall be able to withstand the same atmospheric corrosion conditions that the conductor to which they are associated. 
10. Insulators, which are usually grouped in insulators chains of individual insulators, shall be made in ceramic, glass, silicon rubber, polymers or other materials able to fulfil the insulation role.  
11. All insulators shall be designed to be compatible with the electrical and mechanical requirements imposed on the line. In particular, insulators shall ensure minimum insulation levels to protect against the highest voltage for equipment listed in Article 34 and the minimum voltage protection requirements set in the table below: 

Article 35. Conductors 

Article 36. Fittings and accessories 

Article 37. Insulators 

Table  18 – Minimum withstand voltages for insulators in the MV overhead lines of the Distribution Network 

1. Insulators shall be selected taking into account the need to withstand atmospheric corrosion and pollution, including UV radiation and marine salt. 
2. All metallic elements of insulators shall be galvanized, or protected through equivalent techniques, against corrosion. 
3. Insulators shall grant minimum creepage distances of 31 mm./kV. 
4. Conductors shall be connected through insulators directly to the support structures. 
5. Support structure can be either poles or lattice structures made in steel, galvanized iron, concrete or wood. 
6. Support structures shall be able to withstand the same atmospheric corrosion conditions that the conductor to which they are associated.  
7. In metallic support structures: 

Article 38. Support structures 

4.1.        and any metallic element of any support structure shall not use open profiles less than 4 mm. thick. 

4.2.        Holes shall not be made in profiles below 35 mm. thick. 

4.3.        Buried profiles, if not covered by concrete, shall not be less than 6 mm. thick. 

4.4.        Screws used, if any, must be at least 12 mm. in diameter. 

4.5.        Closed profiles shall be designed to avoid cumulating water inside. 

4.6.        Closed profiles shall not be less than 3 mm. thick.

1. In concrete support structure, vibrated concrete poles and spun concrete poles shall be preferred. 
2. In wood poles, wood shall be treated against rot by humidity and corrosion. 
3. Support structures located in outdoor areas and public areas shall be designed to hinder its scaling to a minimum height of 2 metres.  
4. Stays and struts shall only be used as temporary solution in case of failure, damage, replacement or temporary deviation of the support structure.   
5. Stays installed shall have a breaking stress of at least 1,750 daN and be formed by wires of at least 2 mm. in diameter. 
6. Stays shall be equipped with solutions to regulate their tension without twisting the wires, which is prohibited. 
7. Support structures shall be uniquely identified by means of a number, code or geographic coordinates, which shall be readable from ground level. 
8. Support structures shall be clearly marked with the name of its manufacturer and its type. 
9. Support structures installed in frequented areas shall have attached a warning panel indicating electrical hazard. 

Article 39. Mechanical calculations 

1. Mechanical calculations for any element of the line shall take into account the following loads: 

1.1.        Permanent loads: all vertical loads caused by the weight of line elements, including support structures and foundations. 

1.2.        Wind loads: 

1.2.1.     Wind loads on overhead line elements shall be calculated for a minimum wind speed of 120 km/h. 

1.2.2.     The forces generated by the wind on line elements calculated as per IEC 60826. 

1.2.3.     For each support structure, the forces generated by the wind on each of the conductors connected to it and the associated equipment shall be considered. 

1.3.        Forces created by the imbalance of tensile strengths in the support structures and, as particular scenarios, the case where one of the phase conductors breaks. 

1. Conductors shall not be imposed tensile strengths higher than 2.5 times their breaking stress in the case of multi-thread wire and not higher than 3 times in the case of singlethread wires. 
2. Maximum sag of overhead lines shall be calculated for two scenarios: 

3.1.        taking into account the permanent loads and the wind loads created by a wind of 120 km/h at +15 ºC; and 

3.2.        Taking into account the permanent loads and the maximum operation temperature foreseen for the line, which shall never be lower than 50 ºC. 

1. Fittings and insulators installed shall have a breaking stress higher than 3 times the maximum tensile strength to which they are expected to be exposed. 
2. Fasteners such as bolts, screws and studs shall be at least of class 5.6 as per ISO 898-1. 
3. Foundations and support structures shall be designed so that the forces that prevent pulling out the structure from its foundation (support structure’s weight, foundation’s weight, weight of the soil that would have to be removed to pull out the support structure and resistance of fasteners to the ground, if any) are at least 1.5 times the nominal pull out load to be imposed on the support structure. Article 40. Electrical calculations 
4. Electrical calculation shall be made to obtain the electrical parameters, maximum currents, voltage drops and power losses associated to the MV overhead line under all foreseen operation modes.  
5. MV overhead lines shall be designed to be able to withstand short-circuit currents in case of 3-phase, phase-to-phase, phase-to-earth, double phase-to-earth short-circuits for: 

2.1.        0.5 s for conductors; and 

2.2.        1.0 s for fittings and line accessories. 

1. Maximum current density of each conductor shall be determined by the material and the cross section of the conductor according to the following table or as indicated by the manufacturer: 

Table  19 – Maximum current density for copper conductors for the MV overhead Distribution Network 

1. The maximum current through the conductor shall then be calculated as the product of the maximum current density (σ_max) and the conductor’s cross section (S).  

𝐼 _𝑚𝑎𝑥(𝐴) =  𝜎_𝑚𝑎𝑥∙ 𝑆

1. The voltage drop in a MV overhead line shall be calculated as: 

𝑃 ∙ 𝐿 ∙ (𝑅 + 𝑋 ∙ 𝑡𝑔(𝜑))

                                                       ∆𝑈 (%) =                   10 ∙ 𝑈₂                  

                           Where: 

• P = Power wheeled, expressed in kW. 
• L = length of the line, expressed in km. §     U = line-phase voltage. 
• φ = power factor. 

1. The maximum power that can be wheeled through a MV overhead line can be calculated 

as: 

𝑃𝑚𝑎𝑥𝐼_𝑚𝑎𝑥 ∙ cos (𝜑)

        Or