BS-7671-2008-CORR.1-2008.pdf

This corrigendum contains corrections to BS 7671:2008. For clarification, where appropriate, deleted text has been ruled through and additional text has been underlined. Sufficient of the existing text has been included to enable users to identify the nature and extent of the change. Amend Table 41.1, NOTE 2 and 411.4.5, NOTE by deleting “(typically 2In)”. Amend 434.2.1 as follows: 434.2.1 The regulations in Regulation 434.2 shall not be applied to installations situated in locations presenting a fire risk or risk of explosion and or where the requirements for special installations and locations specify different conditions. Amend 515.3.1 and 515.3.2 by replacing references to “BS EN 50082” and “BS EN 50081” with “BS EN 61000 series”. Amend 533.3 as follows: 533.3 Selection of devices for protection of wiring systems against fault current The application of the regulations of Chapter 43 for fault currents of duration up to 5 s shall take into account maximum fault current conditions. Where the device provides protection against fault current only, account shall be taken of minimum short-circuit fault current conditions. Where the standard covering a protective device specifies both a rated service short-circuit breaking capacity and a rated ultimate short-circuit breaking capacity, it is acceptable to select the protective device on the basis of the ultimate fault current short-circuit breaking capacity for the maximum short-circuit fault current conditions. Operational circumstances may, however, make it desirable to select the protective device on the service short- circuit breaking capacity, e.g. where a protective device is placed at the origin of the installation. Where the short-circuit breaking capacity of the protective device is lower than the maximum prospective short- circuit or earth fault current that is expected at its point of installation, it is necessary to comply with the requirements of the last paragraph of Regulation 536.1 and Regulation 536.5. Amend Table 53.2 as follows: Device Standard Isolation(5) Emergency Switching(2) Functional switching (5) In an installation forming part of a TT or IT system, isolation requires disconnection of all the live conductors. See Regulation 537.2.2.1. Replace 537.1.2 as follows: 537.1.2 Combined protective and neutral (PEN) conductors shall not be isolated or switched except as permitted by Regulation 543.3.4. Except as required by Regulation 537.1.4, in a TN-S or TN-C-S system the neutral conductor need not be isolated or switched where it can be regarded as being reliably connected to Earth by a suitably low impedance. For supplies which are provided in accordance with the Electricity Safety, Quality and Continuity Regulations 2002, the supply neutral conductor (PEN or N) is considered to be connected to Earth by a suitably low impedance. Corrigendum (July 2008) BRITISH STANDARD BS 7671:2008 Requirements for Electrical Installations IEE Wiring Regulations, Seventeenth Edition © The Institution of Engineering and Technology and BSI NO FURTHER ELECTRONIC COPYING WITHOUT WRITTEN PERMISSION Amend 702.411 as follows: 702.411415 Protective measure: Automatic disconnection of supply Additional protection Amend Regulation number 702.411.3.3 to 702.415.2 Note the changing of the above two Regulation numbers effectively moves that group from page 171 to 172. Amend 702.55.1(ii) and (iii) by replacing “702.411.3.3” with “702.415.2”. Amend 705.1, NOTE by deleting “and BS EN 6100-1” Amend Figure 705, bottom left-hand corner, by replacing “150 mm ? 150 mm” with “150 mm x 150 mm” Appendix 1, British Standards to which reference is made in the Regulations Amend as follows: BS 6220:1983 (1999) Electric cables. Single core PVC insulated flexible cables of rated voltage 600/1000 V for switchgear and controlgear wiring Deleted by BS 7671:2008, Corrigendum (July 2008) Appx 15 BS EN 61000 Electromagnetic compatibility (EMC) BS EN 61000 is a multiple part standard 515.3.1 515.3.2 Appx 5 AM Appx 11 para 1 BS EN 6100-1 Glossary of building and civil engineering terms Deleted by BS 7671:2008, Corrigendum (July 2008) 705.1 note Appendix 9, Definitions multiple source, d.c. and other systems Amend Figures 9D to 9M as follows: Change symbol: to: . Appendix 15, Ring and radial final circuit arrangements, Regulation 433.1 Amend Figures 1 and 2 as shown over page: Index Amend as shown: Page 364 - swimming pools- - supplementary equipotential bonding 702.411.3.3(ii) 415.2 Page 366 - swimming pools 702.411.3.3 415.2 Page 372 - swimming pools 702.411.3.3 415.2 Page 373 - swimming pools 702.411 415.2 - swimming pools 702.411.3.3 415.2 Page 379 - starting currents 522.1.1 552.1.1 Page 382 - swimming pools 702.411.3.3 415.2 Page 386 - swimming pools 702.411.3.3 415.2 - supplementary equipotential bonding required 702.411.3.3 415.2 APPENDIX 15 (Informative) RING AND RADIAL FINAL CIRCUIT ARRANGEMENTS, REGULATION 433.1 This appendix sets out options for the design of ring and radial final circuits for household and similar premises in accordance with Regulation 433.1, using socket-outlets and fused connection units. It does not cover other aspects of the design of a circuit such as: Protection against electric shock, Chapter 41 Protection against thermal effects, Chapter 42 Protection against overcurrent, Chapter 43 Selection and erection of equipment, Part 5. 1 Fig 15A RING FINAL CIRCUIT ARRANGEMENTS, REGULATION 433.1.5 The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable (Regulation 433.1.5 refers). This can generally be achieved by: (i) locating socket-outlets to provide reasonable sharing of the load around the ring (ii) not supplying immersion heaters, comprehensive electric space heating or loads of a similar profile from the ring circuit (iii) connecting cookers, ovens and hobs with a rated power exceeding 2 kW on their own dedicated radial circuit (iv) taking account of the total floor area being served. (As a rule of thumb Historically, a limit of 100 m2 has been adopted.) 2.5 mm2 A ring final circuit starts and finishes at the distribution board, where it is connected to a 30 A or 32 A overcurrent protective device. NOTE: Consideration must be given to the need for additional protection by an RCD in accordance with Regulation 411.3.3 and Regulations 522.6.6 to 522.6.8. 2.5 mm2 conductors forming the ring Spur using an FCU connected directly to the ring The number of socket-outlets supplied from a fused connection unit is dependent upon the load characteristics, having taken diversity into account. Unfused spur An unfused spur should feed one single or one twin socket-outlet only. An unfused spur may be connected to the origin of the circuit in the distribution board. BS 1363 socket-outlet Spur using an FCU not connected directly to the ring The number of socket-outlets supplied from a fused connection unit is dependent upon the load characteristics, having taken diversity into account. Fused connection unit (FCU) supplying fixed equipment 2.5 mm2 2.5 mm2 2.5 mm2 1.5 mm2 1.5 mm21.5 mm2 1.5 mm2 Cables should, wherever practicable, be fixed in a position such that they will not be covered by thermal insulation. Where a cable is partially or completely covered by thermal insulation, reference should be made to Regulation 523.6.6 523.7. Fixed equipment Fused connection unit (FCU) to BS 1363-4 Maximum fuse 13 A f u s e Junction box to BS EN 60670-22 or BS 6220. Junction boxes with screw terminals must be accessible for inspection, testing & maintenance or, alternatively, use maintenance-free terminals / connections (Regulation 526.3). NOTE: Conductor size relates to BS 6004 “flat twin & earth” cable and the minimum cross-sectional area for the live conductors only i.e. L & N. Reduced circuit protective conductor size is permitted i.e.: Live = 2.5 mm2, CPC = 1.5 mm2 Live = 1.5 mm2, CPC = 1.0 mm2. 2 Fig 15B RADIAL FINAL CIRCUIT ARRANGEMENTS, REGULATION 433.1 Cables should, wherever practicable, be fixed in a position such that they will not be covered by thermal insulation. Where a cable is partially or completely covered by thermal insulation, reference should be made to Regulation 523.6.6 523.7. All live conductors 2.5 mm2 BS 1363 socket-outlet 20 A overcurrent protective device NOTE: As a rule of thumb Historically, the floor area served has been limited to 50 m2 30 A or 32 A overcurrent protective device NOTE: As a rule of thumb Historically, the floor area served has been limited to 75 m2 Live conductors 4.0 mm2 BS 1363 socket-outlet 2.5 mm2 1.5 mm2 Unfused spur An unfused spur run in 2.5 mm2 cable should feed one single or one twin socket-outlet only. An unfused spur may be connected to the origin of the circuit in the distribution board Spur circuit using an FCU The number of socket-outlets supplied from a fused connection unit is dependent upon the load characteristics having taken diversity into account. A radial final circuit starts and finishes at the distribution board, where it is connected to an 30 A or 32 A overcurrent protective device. NOTE: Consideration must be given to the need for additional protection by an RCD in accordance with Regulation 411.3.3 and Regulations 522.6.6 to 522.6.8. NOTE: Conductor size relates to BS 6004 “flat twin & earth” cable and the minimum cross-sectional area for the live conductors only i.e. L & N. Reduced circuit protective conductor size is permitted i.e.: Live = 4.0 mm2, CPC = 1.5 mm2 Live = 2.5 mm2, CPC = 1.5 mm2 Live = 1.5 mm2, CPC = 1.0 mm2. Fused connection unit (FCU) to BS 1363-4 Maximum fuse 13 A f u s e Junction box to BS EN 60670-22 or BS 6220. Junction boxes with screw terminals must be accessible for inspection, testing & maintenance or, alternatively, use maintenance-free terminals / connections (Regulation 526.3).