EARTH ELECTRODE & GROUNDING CONDUCTOR FOR LV -BS7671 TT & TN-S SYSTEM
Earthing or Earthed:
Earthing or Earthed alternately known as Grounding or Grounded is to describe the connection of metallic parts of an Electrical Installation or an Appliance to Earth.
The conductive mass of earth whose voltage at any point is generally consider as zero. The earth is the reference point for any voltage, eg- the system voltage is 33kv or 33,000 volt means earth to conductor voltage difference is 33kV.
The focus point of this article is on earthed system for LV wiring system accumulation at connection point of utility company and consumer premises.
Customer Earthed system:
Customer earthed system is, where the Customer provides a Main Earth Terminal for the Installation, which is connected to a sufficient number of local Earth Electrodes. This system is also known as TT system when follows the British Standard BS7671 TT system.
Distribution Company Earthed system:
Distribution company earthed system is, where the Distribution Company provides a connection to the Customer’s Main Earth Terminal using the distribution network Earthing system. Generally Distribution Company makes earthing via the armoring or metallic sheath of the main incoming supply cables. This system is also known as TN-S system when it follows British Standard BS7671 TN-S system.
Earth Conductor & Earth Electrode:
The protective conductor that used to connect the exposed metallic parts of an electrical installation and associated appliances to earth is Earth Conductor. This may also be known as the Circuit Protective Conductor (CPC) or Earth Continuity Conductor (ECC) or commonly known as the ‘earth wire’.
Earth Electrode is a piece of conductor rod or group of conductors in closed contact with Earth, providing a good electrical connection to Earth having measurable low resistance of earth, earth resistance for premise wiring is desired below one Ohm. Earth Electrode also known as Earth Rod or Grounding Rod.
Main Earth Terminal:
The main connection point at which the nominal value of Earth Resistance for an installation is taken and at which Earth Conductors from the Earth Electrodes will be connected. This will normally be at or close to the customer connection point.