18th Edition Intro: What Electrical Designers and Electricians Need to Know

April 5, 2018

wiring regulations

If you are involved in the electrical building industry you will no doubt be aware that the 18th Edition to the Wiring Regulations (BS 7671:2018), is due to be published on 1 July 2018, and will come into effect for all installations designed after 31 December 2018.

It is essential that anyone working in this area is familiar with the regulations, and any changes that are distinct from the 17th Edition, BS7671 - Amd 3.

Details are subject to change up to the final publication of the regulations, but here we present some of the changes and what we know about the 18th Edition so far.

Energy efficiency

One of the most significant changes in the 18th Edition is the addition of regulations pertaining to energy efficiency. It was originally thought that this would form a whole new section (Part 8) of the regulations. It was confirmed in February 2018 that this section would not be added but a new entry in the Appendix (Appendix 17 – Energy Efficiency) will still be included.

This is the first time energy efficiency considerations have been set down in the regulations. Designers/installers will have to consider how to get the required performance and meet all safety standards for the lowest consumption.

The effects could be minor for some and substantial for others. Draft proposals, include allowing clients to specify required energy efficiency measures across a number of different areas, including lighting, electric vehicles, metering, and cable and transformer losses.

This is certainly one area where the final version will be of great interest to everyone.

Protection against electric shock

There are a number of additions and changes set to be included in Chapter 41: ‘Protection against electric shock’.

Drafts now state, for example, that “metallic pipes entering the building having an insulating section at their point of entry need not be connected to the protective equipotential bonding”. This should lead to a reduction in both testing and installation work, due to the fact that these connections were formerly mandatory.

Regulation 411.3.2.2 is being changed in relation to automatic disconnection in case of a fault. Socket-outlets rated up to 63A must now disconnect at 0.4 seconds instead of the 5 seconds previously set down in the 17th Edition of the regulations.

Where socket systems with current ratings of up to 20A previously required ‘Additional Protection’ under Regulation 411.3.3, this maximum range is now being extended to 32A. All socket-outlets up to this rating and all mobile equipment for outdoor use up to the same rating will need additional protection via an RCD, with a rated residual operating current not exceeding 30mA. There is an exception to omit RCD protection where, other than a dwelling, a documented risk assessment determines that the RCD Protection is not necessary (This was a change from the draft but has been confirmed in future documentation presented by the IET). 

A new regulation is also being introduced that requires circuits with luminaires to be provided with Additional Protection. Again, this will be by means of an RCD with a rating not exceeding 30mA. Essentially, this means that more complicated and costly protective devices may need to be considered.

Protection against voltage and electromagnetic disturbances

This is covered in part by Clause 443 and, according to the Institution of Engineering and Technology (IET), this clause is likely to get a major overhaul.

Instead of considering whether protection against transient overvoltage is required, the new provisions will consider how any overvoltage could affect several different elements.

Transient overvoltage would have to be protected against where it affects:

  • Human life or health (such as in medical and healthcare facilities)

  • Public services and/or cultural heritage facilities (a loss of public services, museums, large-scale IT provision)

  • Commercial and industrial interests (such as manufacturing, banks, hotels, farms and commercial centres)

In other cases, risk assessment will need to be carried out. In addition to the examples above, there is an exemption on the need for risk assessment in single dwelling units where certain criteria are met.

Protection against thermal effects

Protecting against the dangers of fire is an obvious focal point for electrical regulations. Chapter 42 is intended to provide protection for people, property and livestock against thermal effects caused by electrical equipment. As well as the risk of fire, this includes burns and overheating.

A new requirement may be introduced regarding the installation of arc fault detection devices (AFDD) to protect against the risk of fire initiated by an arc originating from a fault current. This is due to the fact that, while RCDs are able to detect earth faults and therefore reduce the risk of fires, they cannot mitigate the risk of fire due to series or parallel arcing across live conductors.

This stipulation demands more details. It may be the case that space requirements in boards will have to be increased to account for the physical space requirements of AFDD units.

Drafts and future changes

There will be numerous other things to look out for, including additions and amendments to the installation of cables, earthing arrangements and periodic inspection and testing.

It’s worth restating, however, that nothing is final until the 18th Edition is published in July 2018. The above information is based on access to draft versions but these are subject to change in the final document.

If you are looking for 18th Edition courses and qualifications, you should be wary of providers offering products too early, as any changes in the final draft could mean courses contain incorrect or misleading information.

For a more detailed look at everything we know about the regulations so far, access our free guide: 20 Things You Need to Know About the 18th Edition.

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