SANS 10142-1 – 2012 Edition 1.8 (SOUTH AFRICAN NATIONAL STANDARD) The wiring of premises Part 1: Low-voltage installations There is two section to Bonding and Earthing Regulation 6.12 and 6.13 depending on what specific requirements is look at. 6.12 Earthing NOTE 1 This subclause addresses earthing arrangements, earth continuity conductors and equipotential bonding in order to ensure the safety of the electrical installation. Functional requirements for information technology installations are addressed in annex N. Earthing arrangements may be used jointly or separately for protective and functional purposes according to the requirements of the electrical installation. Requirements for protective purposes always take precedence. NOTE 2 The requirements for earthing arrangements are intended to provide a connection to earth that a) is reliable and suitable for the protective and functional requirements of the installation (for example, surge arresters, etc.), b) can carry earth fault currents, protective conductor currents and * ¹leakage currents to earth without danger from thermal, thermo mechanical and electromechanical stresses and from electric shock that arise from these currents, and c) where relevant, is also suitable for functional requirements. Note: * ¹leakage currents (Protection of live) See attached document 6.12.2 Earth electrodes An earth electrode might be required for purposes such as antennas and surge voltage protection. Earth electrodes shall comply with the requirements of SANS 1063 and shall be installed in accordance with SANS 10199. (see document SPD’s) 6.12.3 Earthing of exposed conductive parts 6.12.3.1 The following conductive parts shall be earthed: a) all exposed conductive parts of an installation other than those described in 6.12.3.2; NOTE Metal enclosures on PVC conduit should be earthed if they can become live and can be touched. b) all conductive cable sheaths and armouring, wireways and catenary wires; c) the earthing terminal of a socket-outlet; d) the secondary winding of a transformer if it is not a safety transformer; e) earthing terminals of all permanently connected electrical equipment and appliances; f) conductive parts of discharge luminaires *²and equipment that need special earthing arrangements; and g) all class I equipment. Note : *²and equipment that need special earthing arrangements.(This is misread by electrical contractors) Special earthing arrangements deals with all aspects For Example: SANS 10313: Protection against lightning SANS 10292 2001 1.01 Earthing of low-voltage (LV) distribution systems. Occupational Health and Safety Act, Act 85 of 1993: Electrical Machinery Regulations SANS 10123 2001 1.01 The control of undesirable static electricity Also earthing (Grounding of Sub Stations) IEEE 80 NB* Regulation 8.7 8.7 Testing 8.7.2 Continuity of bonding Test the continuity of the bonding between the consumers earth terminal and all exposed conductive parts using a supply that has a no-load d.c. or a.c. voltage of 4 V to 24 V, and a current of at least 0,2 A. In each case, the resistance shall not exceed 0,2 Ω. 8.7.3 Resistance of earth continuity conductor Use a resistance meter to measure the resistance of the earth continuity conductors between the consumers earth terminal and the earthing terminals of all points of consumption and switches. The values shall not exceed those given in table 8.1. NOTE In the case of metallic roofs, gutters, down pipes and waste pipes (see 6.13.2.4), the resistance of the earth continuity path shall not exceed 0,2 Ω. Annex N (informative) Earthing arrangements and equipotential bonding of information technology installations for functional purposes C Extraneous conductive part Conductive part that does not form part of the electrical installation and is liable to introduce an electric potential, generally the electric potential of a local earth. C1 water pipe (metal – from outside) C2 waste-water pipe (metal – from outside) *³ C3 gas pipe with insulating piece (metal – from outside) C4 air conditioning C5 heating system C6 water pipe (metal – for example, in a bathroom) C7 extraneous conductive part within arms reach of exposed conductive parts M Exposed conductive part Part of equipment which can be touched and which is not normally live, but can become live when basic insulation fails. Note : * ³ C3 gas pipe with insulating piece (metal – from outside). We teach earthing which shows our learners proper earthing methods especially hazardous location (See sample Pic)
Posted on: Fri, 21 Feb 2014 11:15:48 +0000
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