How the 18th Edition brings opportunities for you

May 14th 2019

With the 18th Edition of the IET Wiring Regulations come new business opportunities. Whether that’s a need for an increased number of devices per installation or new devices entirely, it’s important to understand where the opportunity lies, explains Jim Hutchison, National Sales Manager for Wylex.

The 18th Edition Wiring Regulations call for overvoltage protection, considerations for the unwanted tripping of RCDs (residual-current device), additional protection by 30mA RCD and for devices for protection against the risk of fire. Wylex consumer units and devices provide solutions for each of these in turn, making them ‘must stock’ items.

Overvoltage protection

In certain circumstances overvoltage protection is mandatory. For all other situations a risk assessment is necessary. However, if there is no risk assessment carried out overvoltage protection must be installed and in single unit dwellings the final decision is made on a value judgement.

To meet this requirement, installations will have to use SPDs (surge protection devices) and designers & installers will have to include more SPDs in their installations.

Unwanted tripping of RCDs

To avoid unwanted tripping of RCDs from PE currents leaking through the protective conductor during normal (non fault) operating conditions the designer must ensure that accumulated PE current is less than 30% of the RCD rating (regulation 531.3.2). This may be difficult to achieve but fortunately the regulations provide an alternative which is to use an individual RCBO (residual-current circuit breaker with overcurrent protection) on each circuit, each RCBO would be powering fewer items of equipment and avoiding excessive PE currents in order to maintain power continuity and occupier safety.


Additional protection

Today’s typical domestic installation will have 30mA RCD protection on every circuit, especially as another new regulation in the 18th Edition (411.3.4) has extended the use of 30mA RCDs to include all lighting circuits in dwellings. All of which means that each circuit in a consumer unit needs to have several types of protection against a variety of potential faults. Lighting circuits should not be grouped with power circuits on one RCD. Lighting circuits ought to be on individually protected circuits so as to remain on at all times and not plunge people into darkness when other circuits are faulty. See Chapter 31 Division of the Installation. The simple way to comply is to use RCBOs.

Protection against the risk of fire

The 18th Edition recognises that risk of injury may result from arcing or burning (131.1) and it includes requirements for installations to be so arranged that the risk of ignition of flammable materials due to high temperature or electric arc is minimized, and requires people, livestock and property to be protected against the risk of burns (Chapter 13).

Electrical fires caused by dangerous arc faults typically occur at loose connections, poor terminations, or in impacted and damaged leads and cables, or through old, weak and failing insulation. AFDDs (Arc fault Detection Devices) can decrease the likelihood of electrical fires from these conditions by detecting the arcing conditions before the overheating and ignition of flammable materials.

AFDDs detect arc faults that cannot be detected by RCDs or MCBs. These new devices use digital technology to provide additional protection against fires caused by arcs in AC 230V final circuits, making them a must-have for new installations.

Only Use Manufacturer Approved Parts

Another new regulation, 536.4.203, refers to devices and components that are used in low voltage assemblies, such as consumer units, must only be those that have been declared suitable for that purpose by the manufacturer of the assembly. Or put another way: only use manufacturer approved parts, don’t mix brands of devices or control items.  Using unapproved parts will invalidate manufacturer guarantees and may result in an unsafe installation.

Get the latest on the 18th Edition

To understand these requirements in more detail, we have Bitesize look at some of the new content in the 18th Edition Wiring Regulations. It has been produced in order to help simplify and emphasise certain key points.

This bitesize document includes requirements for overvoltage protection, prevention of unwanted tripping of RCDs and the use of AFDDs - to name a few.

Download our bitesize guide here. 

We also have a host of help and information on the 18th Edition with our dedicated online area. Here we cover a hosts of topics, including the key changes, Arc Fault Detection Devices and Surge Protection.

Check out our 18th Edition section here. 

Designers and installers should obtain their own copy of BS7671:2018 and follow the requirements and recommendations in the 18th Edition of the IET Wiring Regulations.

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