Making changes to increase wiring safety

7th August 2017
Source: Hager
Posted By : Joe Bush
Making changes to increase wiring safety

Paul Collins, Technical and Training Manager, Hager, has highlighted three key safety driven changes that could emerge as the 18th Edition of the Wiring Regulations Standard BS 7671 review progresses through the public consultation phase.

The Draft for Public Comment on the 18th Edition of the Wiring Regulations has now been published and highlights a number of potential changes to the existing regulations. The document does remain a draft at this stage and is subject to further change, revision and amendment.

The overall objectives for the review are to ensure harmonisation with current European standards, provide an opportunity to clarify existing regulations and allow new technology and methodology to be incorporated into the wiring regulations.

Having scrutinised the draft regulations as they currently stand, three key areas covering protection against electric shock, thermal effects and over voltages will be of primary interest to all stakeholders across the industry.

1. Chapter 41 – Protection against electric shock
The protective measure of automatic disconnection of supply gives maximum disconnection times in Table 41.1. This table at present applies to final circuits up to and including 32A.

It is proposed that this table will apply to final circuits up to 63A that contain one or more socket outlets and up to 32A if only fixed equipment is connected. The usual time of 0.4s for systems where the U0 is 230V remains unchanged for a TN system.

The requirements of regulation 411.3.3 for protection by means of an RCD up to 30mA currently includes socket outlets up to a 20A rating or for mobile equipment used outdoors up to 32A.
There is also currently an exception allowed by labelling socket outlets for a particular use or by carrying out a risk assessment to alleviate the requirement of using RCDs where the installation is not a dwelling.

The proposed change in the draft will now include socket outlets up to 32A and there is no exception allowed, which means that every socket outlet up to the rating of 32A will require RCD protection no matter what the type of installation or equipment it is supplying.
A new regulation, 411.3.4 will require RCD protection up to 30mA of circuits supplying luminaires in domestic installations regardless of their wiring method.

2. Chapter 42 – Protection against thermal effects
Section 421, Protection against fire caused by electrical equipment could have a new regulation. The proposed 421.1.7 introduces arc fault detection devices saying they may be used to provide additional protection against fire caused by arc faults.

3. Section 443 – Protection against over voltages
This entire section has now been rewritten, with an exception for dwellings where the value of the installation does not justify the inclusion of overvoltage protection.

The draft suggests that they shall be provided where the result of an overvoltage would affect different aspects - such as danger to life, public services, commercial or industrial activity. This is likely to mean there will be a requirement to install surge protection devices.

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