17th Edition Amendment 3

The third amendment of the BS7671:2008 wiring regulations was published on the 5th January 2015 and provided a six month grace period for electrical installers to get up to speed with the new standards. From July 2015, all electrical installations were required to be compliant with BS7671:2008+A3, except 421.1.203, which came into full affect on the 1st January 2016.
What caused the change?
The BEAMA was working closely with the Electrical Safety First and the London Fire Brigade and discovered that statistics displayed consumer units caused five domestic fires a week. Therefore, additional specifications were included into the regulations to improve personal safety within homes.
Terminology alterations:

  • A list of abbreviations has been added to Amendment 3
  • The definition of a ‘competent person’ has been removed
  • The term ‘skilled person’ has been added and refers to an electrician with adequate education, training and skills
  • The term ‘Instructed person’ has also been added and refers to someone who is adequately supervised by a skilled person to perceive electrical risks and avoid hazards
The main changes:
  • Regulation 421.1.201 was included, requiring that within a domestic dwelling all consumer units and similar switchgear must have an enclosure manufactured from non-combustible material, or be in a cabinet/enclosure constructed of non-combustible material and complying with regulation 132.12, regarding to the accessibility of electrical equipment
  • Chapter 41 now stipulates that RCD protection is required for all installations up to 20A and for mobile equipment (for use outdoors) up to 32A. However, this rule is not applicable where a socket outlet is specifically labelled or in a installation that is not within a dwelling, where a documented risk assessment determines that RCD protection is not necessary
  • A new section – 424 Protection Against Overheating, has been added regarding locations containing forced air heating systems or appliances producing hot water or steam
  • Regulation 521.201 has been included incorporating requirements for the methods of support wiring systems in escape routes. In addition to this, the previous regulations regarding the selection and erection of wiring systems has been altered, removing the reference “under the supervision of a skilled or instructed person”
  • Section 551 – The common rules regarding compliance with standards now requires all equipment to be suitable for the nominal voltage, and also requires certain information to be noted on the electrical installation certificate
  • Section 512 now makes reference to the Electromagnetic Compatibility (EMC) directive
  • Section 557 has been included to focus upon auxiliary circuits, specifically focusing on issues such as a.c. or d.c. power supplies, protection against overcurrent and wiring systems
  • Section 559 -The requirements in Section 559 for outdoor lighting and installations, and extra low voltage lighting installations have been moved to sections 714 and 715 respectively
  • Regulation 701.411.3.3 now requires all low voltage circuits serving zones 1 and 2 to be RCD protected, as well as all low voltage circuits passing through but not serving zones one and two
  • Section 715 now includes extra requirements for isolation, switching and control, with regards to extra-low voltage lighting installations
  • Regulation 717.551.6 has been added to 717 - Mobile or Transportable units, prohibiting units with different power supplies and earthing systems from being interconnected
  • Appendix 3 has been altered to stipulate that the maximum earth fault loop impendence must take account of the Cmin factor given in PD CLC/TR 50480
  • Appendix 4 - tables 4A3, 4C3 and 4F3A have been modified and reference is now made to the national annex PD CLC/TR 50480, giving calculation methods for cable resistance. Reference has also been made to the standard for calculating fault currents and circuit impendences
  • Appendix 6 - the schedule of inspections, has been removed and replaced with: ‘examples of items requiring inspection during initial verification’ and a ‘schedule of inspections (for new installations work only) for domestic and similar premises with up to 100 A supply’
  • Appendix 14 - The equation for earth fault loop impendence has been altered to consider the Cmin voltage factor given in PD LC/TR 50480
Please note: the above is only a guide of the main changes in Amendment 3, for the exhaustive list of changes please refer to BS 7671:2008.