BS 7671 – IET Electrical Regulations: The key changes

The 18^th edition of the BS7671 IET Wiring Regulations is due to be published on July 2 this year and will come into force on January 1, 2019. The regulations outline UK compliance requirements for wiring in new and amended electrical installations. Any installations designed after December 31 this year will need to comply with this latest edition.

The Wiring Regulations – which are the essential reference guide for electrical industry professionals – are being updated to ensure the UK stays in step with changes to international and European standards. The updates also ensure that the regulations accurately reflect the industry and its needs, as well as maintaining the safety of both electrical professionals and members of the public.

Some of the key changes in the new 18^th edition concern requirements which give further protection from fire and overvoltage, while there are additions around energy efficiency, amends to requirements for electric vehicle charging installations, and new guidance on energy efficient production and storage installations.

Here we take a brief look at some of the key changes and additions since the last edition of the Wiring Regulations.

What are the key changes?

Amends to current sections

• Chapter 41 has seen a number of major changes to ensure further protection against electric shocks. Among these are amends to regulations 411.3.1.2, 411.3.2.2, 411.3.3 and 411.4.3, while 411.4.4 and 411.4.5 have been redrafted.
• Alongside smaller revisions, there has been a significant change within Chapter 52, which concerns the selection and erection of wiring systems. Regulation 521.11.201, which details how wiring systems in escape routes should be supported, has been replaced by a new regulation, 521.10.202, which applies to all cables throughout the installation rather than the escape routes only, and requires them to be adequately supported in the event of a fire, to safeguard against their premature collapse.
• The numbering of regulations within Part 6, which deals with inspection and testing, has been completely changed to fit with the CENELEC standard. Two new chapters, 64 and 65, have been created using the content of chapters 61, 621 and 63, which have been deleted.
• Amends have been made to regulation 722.411.4.1 within section 722 which concerns electric vehicle charging installations. Alongside some smaller changes, a key amend has been regarding the use of a PME supply, with the exception for reasonably practicable being deleted.

New sections / regulations

• New additions to Chapter 41 include a new regulation 411.3.4, and the insertion of a new regulation group (419) for occurrences where automatic disconnection according to regulation 411.3.2 is not feasible. Also, in this chapter, the regulations around IT systems (411.6) have been reorganised, with 411.6.3.1 and 411.6.3.2 being deleted, 411.6.4 redrafted and the new regulation 411.6.5 inserted.
• There is a new regulation in Chapter 42 which lays down the requirements for the protection of people, animals and property from electrical fires, burns and overheating. Regulation 422.2.1 provides further protection against thermal effects and recommends the use of AFDDs.
• Chapter 44 has been redrafted to provide further protection from overvoltages caused by the atmosphere or switching. A risk assessment must be carried out to determine if protection against transient overvoltage is required, but protection always has to be provided where the overvoltage causes
  • serious injury or death
  • interruption or damage to public services or cultural heritage buildings
  • disturbance to commercial or industrial activity
  • an impact on a large group of people within the same area
• Chapter 46 is a new chapter about devices for isolation and switching, and aims to lower the risks involved with electrical installations or electrically powered equipment.
• Chapter 53, which concerns general requirements for protection, isolation, switching, control and monitoring, has been completely revised to provide requirements for the selection and erection of devices which fulfil any of these functions. The main technical change is in section 534 and concerns the selection requirements for the voltage protection level.
• In Chapter 54, four new regulations have been added, with 542.2.3 and 542.2.8 concerning earth electrodes, and 543.3.3.101 and 543.3.3.102 concerning switching devices in protective conductors.
• In Section 710 which covers medical locations, there have been some small changes such as removing Table 710 and changes regarding equipotential bonding. However, there is also a new regulation 710.421.1.201 regarding medical locations of group 2. This states that for all final circuits supplied by a medical IT system, AFDD shall not be used.
• There is also a new section, 730, about onshore installations which supply inland navigation vessels in ports and berths. This section has been created to distinguish the size of the supply needed for such vessels as opposed to those in marinas.
• The section covering floor and ceiling heating systems – section 753 – has been extended to cover embedded electric heating systems for surface heating, as well as required documentation. It also covers electric heating systems for preventing frost or de-icing but does not cover heating systems for industrial and commercial applications complying with IEC 60519 and IEC 62395.
• Appendix 14 now has details about prospective fault current, while the part about earth fault loop impedance has been moved to Appendix 3.
• A new appendix – number 17 – focuses on energy efficiency. It applies to new electrical installations as well as any changes to existing ones, such as lighting, metering, and electric vehicles. It gives recommendations on how less electricity can be consumed, while at the same time ensuring safety and quality. An installation may earn points for energy efficiency performance, which can be added together to give it a rating from EIEC0 to EIEC4.