A Guide to the 18th Edition of the Wiring Regulations

Published:  02 July, 2018

BS 7671, ECA, Steve Martin, 18th Edition of the Wiring Regulations
Steve Martin, ECA

Steve Martin, ECA Director of Technical, gives an overview of the key changes to the 18th Edition of the Wiring Regulations that were published this month and come into full effect on January 1 2019.

The Wiring Regulations, the essential publication for all professionals in the electrotechnical engineering services industry, has undergone a new round of changes (the 18th Edition) to keep up with the ever-evolving ways we design and install electrical installations.

Also known as BS 7671, the publication includes some subtle changes in wording, such as ‘in use without a fault’ being replaced with ‘under normal conditions’, in addition to some Regulations in the 650-page document being introduced for the first time, rewritten or removed entirely.

Existing installations that have been installed in accordance with earlier editions of the Regulations may not comply with this edition in every respect, but this does not necessarily mean that they are unsafe for continued use or require upgrading.

How will building managers be affected?

Other significant changes to BS 7671:2018 include …

Chapter 41 Protection against electric shock:

Metallic pipes entering the building having an insulating section at their point of entry need not be connected to the protective equipotential bonding.

The maximum disconnection times stated in Table 41.1 now apply for final circuits up to 63 A with one or more socketoutlets, and 32 A for final circuits supplying only fixed connected current-using equipment.

Regulation 411.3.3 has been revised and now applies to socket-outlets with a rated current not exceeding 32A. There is an exception to omit RCD protection where, other than in a dwelling, a documented risk assessment determines that RCD protection is not necessary.

A new Regulation 411.3.4 requires that, within domestic(household) premises, additional protection by an RCD shall be provided for AC final circuits supplying luminaires.

Chapter 42 Protection against thermal effects

A new Regulation 421.1.7 has been introduced, on the installation of Arc Fault Detection Devices (AFDDs).

 • Regulation 422.2.1 has been redrafted.

 • Reference to conditions BD2, BD3 and BD4 has been deleted.

 • A note has been added stating that cables need to satisfy the requirements of the CPR Construction Products Regulation) in respect of their reaction to fire.

Chapter 44 Protection against voltage disturbances and electromagnetic disturbances

Section 443 − The AQ criteria (conditions of external influence for lightning) for determining protection against transient overvoltages has been deleted. Instead, protection against transient overvoltages has to be provided where the consequence caused by overvoltage:

(a) results in serious injury to, or loss of, human life, or

(b) results in interruption of public services/or damage to and cultural heritage, or

(c) results in interruption of commercial or industrial activity, or

(d) affects a large number of co-located individuals.

For all other cases, a risk assessment should be performed.

Chapter 52 Selection and erection of wiring systems

Regulation 521.11.201, which gives requirements for the methods of support of wiring systems in escape routes, has been replaced by a new Regulation 521.10.202, which requires cables to be adequately supported against their premature collapse in the event of a fire. This applies throughout the installation (not just in escape routes).

Section 722 Electric vehicle charging installations

This section contains significant changes to Regulation 722.411.4.1 concerning the use of a PME supply. The exception concerning ‘reasonably practicable’ has been deleted plus changes have also been made to requirements for external influences, RCDs, socket outlets and connectors.

BS 7671 is not retrospective, so the changes are aimed at new installations. However, the 18th edition has highlighted some areas that were perhaps lacking clarity in the past.

ECA would recommend that building owners and managers continue to ensure their buildings are kept up to date by carrying out regular inspections of electrical systems by suitably skilled and competent contractors, to highlight any potential failings and areas of improvement.

Energy efficiency

One notable draft section is missing from the 18th Edition: Part 8, Energy Efficiency.

Energy Efficiency, a completely new part and probably one of the most controversial introductions to the 18th Edition, was presented last summer during the Draft for Public Comment (DPC) stage, a period where industry had its say as the revised standard became public for the first time. Previously, BS 7671 was considered a safety standard in for preventing shock and fire.

Although the proposed Part 8 has disappeared from the Wiring Regulations, energy efficiency will still play a key role in BS 7671. It will do as a tool to help meet the requirements to Part L of the Building Regulations in both England and Wales and conservation requirements of Scotland and Northern Ireland. But it is now a condensed `Informative Appendix’.

To many readers the concept of energy efficient electrical installations is nothing new. Regardless of its inclusion into BS 7671, a good design will take into consideration: maximum demand; load profiles; power factor correction; location of equipment; controls, such as lighting control; harmonics and cable sizing.

There are a range of other changes within the 18th Edition. More information on these changes, training and other industry updates can be found at the link below.



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