Energy Efficiency and the 18th Edition by Steve Martin of ECA

Steve Martin takes us through the upcoming changes to the Wiring Regulations:

The official list of changes to the 18th Edition of the IET Wiring Regulations, otherwise known as BS 7671, has been announced. This provides us with a general overview of what is expected prior to the 18th Edition being published on 2 July 2018 and coming into full effect on 1 January 2019. Notably, this comes with one considerable draft section missing − 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. This came 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. Until then, BS 7671 had only ever been considered as a safety standard in terms of preventing electric 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 an aid in meeting the requirements to Part L of the Building Regulations (conservation of fuel and power) in both England and Wales and conservation requirements of Scotland and Northern Ireland. But it is now a condensed `Informative Appendix’.

Electrical installations

Appendix 17 − Energy efficiency will now provide recommendations for the design and implementation of electrical installations, including installations having local production and storage of energy, for optimizing the overall efficient use of electricity. The recommendations within the scope will apply to the new and modification of existing electrical installations. However, most will not apply to domestic and similar installations.

 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.

As the world continues to strive to reduce energy consumption, the UK still has an obligation to implement International and European standards on energy efficiency. As such the intention of Appendix 17 is that, it should be read in conjunction with BS IEC 60364-8-1 to provide a systematic continual assessment of energy efficiency.

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

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 socket-outlets, 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.