Introduction section1: general requirements

SECTION - 5

1. 
   CONSUMER'S EARTHING SYSTEM
   

1. 
   An earthing system should be of the highest integrity and of robust construction to ensure that it remains safe and will not endanger the health and safety of persons or their surroundings. Every consumer installation shall be provided with separate earthing system within the consumer’s plot limits, installed and maintained by the consumer.
   

2. 
   Each consumer's earthing system shall comprise of ‘Earth electrode/s' main earth lead conductor connected between the 'Earth electrode/s' and the consumer's main earthing terminal/s or earth busbar, Earth continuity conductors (ECCs) shall be provided for every outgoing circuits from the main, sub-main & final distribution boards, equipotential bonding of all metal work & exposed conductive parts and enclosures, etc.
   

3. 
   BS 7430 shall be referred for guidance.
   

4. 
   Selection of the material for an earthing conductor should take into account the compatibility with the material of the earth electrode, and for a conductor installed in the grounds, the corrosive effect of the soil.
   

5. 
   The consumer's earthing system shall be connected to DEWA earthing system (incoming supply cable armour/Earth continuity conductor, as approved by DEWA).
   

6. 
   MV, LV, ELV Networks, Private Generators & Lightning Protections shall have separate earthing networks and shall not be connected with the main Electrical Earthing System
   

7. 
   Earthing System in General Must be of low electrical resistance , good corrosion resistance , able to dissipate high fault current repeatedly
   

8. 
   An earthing system should be of highest integrity and of robust construction to ensure that it remains safe and will not endanger the health and safety of persons or their surroundings.
   

9. 
   The Consumer main earthing connection shall be combined of TN-S. The exposed- conductive-parts of all the electrical equipment of the installation shall be connected by means of circuit ECCs to the main earthing terminal. The earth fault loop impedance should be sufficiently low for the protective device (fuse, circuit breaker, RCD) to operate in the required time in event of fault to earth.
   

10. 
    In all cases the Neutral and Earth Conductors shall be kept separate and not connected together at the main earth terminal or at any other point in the customers’ installation.
    
11. 
    Where a number of installations have individual earthing arrangements, any ECC common to these installations shall either be capable of carrying the maximum fault current likely to flow through them or to be earthed within one installation only and insulated from the earthing arrangements of any other installation.
    

12. 
    Foundation metalwork in concrete may be used as a readymade and effective earth electrode. The total electrode area formed by the underground metalwork of large structure may often be used to provide an earth resistance lower than that obtainable by other methods; overall values well below 1ohm are obtainable. It is important that consideration is given to the possibility of corrosion of the metalwork reinforcement; the products of corrosion occupy a greater volume than the original metal and cracking might occur. In particular, continuous earth currents shall be given attention; a possible source of such current might be incompatibility with other buried metalwork, including other types of earth electrode to which foundation metalwork may be bonded (It might be necessary to consider the need for cathodic protection. Damage to the concrete in the form of cracking, due to arcing or the rapid evaporation of moisture, can occur where the long-term duration earth fault currents exceed the carrying capability of the electrode. This situation is unlikely to arise if the electrode has a resistance sufficiently low to avoid dangerous voltages to earth .Where, in structures made of bolted sections, the electrical continuity of the structural joints cannot be relied upon to form permanent and reliable earth bonds it is necessary to install loops bonding across these joints.)
    

13. 
    The use of water mains for earthing purposes shall not be permitted. In general, metallic pipes, e.g. for gas, oil, compressed air, or drainage, shall only be bonded to the protective conductors but not used for the sole means of earthing.
    

14. 
    Earth electrodes shall not be installed close to a metal fence, unless they are used for earthing that fence; this is to avoid the possibility of the fence becoming live and thus dangerous at points remote from the substation, or alternatively giving rise to danger within the resistance area of the electrode by introducing a good connection with the general mass of the earth.
    

2. 
   
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