Published:
2 May 2014
Category:
Technical articles
We take a brief look at Amendment 3 to BS 7671:2008 Requirements for Electrical Installations – and the resulting changes on the design, erection and verification of electrical installations. The information was taken from an article originally published in Wiring Matters 50 – March 2014 by Geoff Cronshaw, which readers can download by going to the IET website:
The draft proposals are outlined below, but remember that not all of the proposals may be included in the final version of Amendment Number 3.
Part 2 Definitions - These will be expanded and modified in terms of, for example, ‘skilled and instructed persons’. Such changes will be reflected throughout the wiring regulations.
Chapter 52 Selection and Erection of Wiring Cables:
Cables concealed in a wall or partition - Cables concealed in a wall or partition (at a depth of less than 50 mm) must be protected by a 30 mA RCD for all installations (other than a few special exceptions).
Section 557 Auxiliary Circuits - This is a new section covering auxiliary circuits for LV electrical installations.
Section 717 Mobile and Transportable Units - There are changes to reduce the risks associated with such units, such as automatic disconnection by RCD and other requirements.
Regulation 717.413 will be introduced. It will require an insulation monitoring devices and earth electrodes to be installed for automatic disconnection under certain circumstances.
Regulation 717.551.6 will be added. This will prohibit the interconnection of units with different power supply systems and earthing systems without special precautions.
Regulation 717.551.7.2 will be added, which will give additional requirements for installations where gensets may operate in parallel with other sources.
Sections 559, 714 and 715: luminaires and lighting installations - Amendment 3 will introduce a number of notable changes to align the BS 7671 requirements with the both latest IEC and CENELEC standards in terms of outdoor and ELV lighting, devices connecting luminaires to the supply, protection of cables against heat and more.
Section 714 Outdoor Lighting Installations - There will be a requirment for additional RCD protection by 30mA RCD for telephone kiosks, bus shelters, advertising panels and town plans, and individual circuits will have to be isolated.
Chapter 41 Protection Against Electric Shock - Changes in definitions noted, plus a requirement for RCD protection for socket outlets up to 20A for all installations - with a special exception.
‘Cmin’ factor - maximum earth fault loop impedances given in the tables will be revised to take into account the Cmin factor, which is the minimum voltage factor to take account of voltage and other variations.
Chapter 42 Protection Against Thermal Effects - Regulation 421.1.200 has been introduced and will require switchgear assemblies, including consumer units, to have greater fire protection.
Appendix 6 Model Forms for Certification and Reporting - This contains the electrical installation certificate, the minor works certificate and the electrical installation condition report (EICR). Amendment 3 will make a small number of changes to the EICR and associated notes, including a requirement to carry out an inspection within an accessible roof space where electrical equipment is present in that roof space.
Important: this article does not include all of the changes that are expected in Amendment Number 3 to BS 7671, the 17th Edition of the IET Wiring Regulations. For more information refer to the DPC on the IET website - go to http://www.theiet.org/resources/wiring-regulations/index.cfm or http://electrical.theiet.org/wiring-regulations/updates/index.cfm