At a glance - the 17th Edition

The revised standard will include the changes necessary to maintain technical alignment with European Harmonization Documents. It's important to note that all of the regulations have been renumbered to align with the International Electrotechnical Commission's (IEC) numbering system. This has also involved partial restructuring of the standard with Part 6 becoming Part 7 and vice-versa.

Parts 1 - 5:

But let's start at Part 1; additional regulations relate to the requirements to protect against voltage disturbances and to implement measures against electromagnetic influences. Part 2, 'Definitions', includes a number of significant new and amended definitions. New requirements relating to safety services and continuity of service considered necessary during the intended life of the installation are addressed in Part 3.

There are several significant changes to Part 4, 'Protection for safety'. Whilst the fundamental principles of shock protection remain the same, the changes to definitions such as basic protection for direct contact and fault protection for indirect contact, along with a partial restructuring of Part 4 (such as Chapter 41 which now includes parts of Chapter 47) means that those readers familiar with the 16th Edition will need to spend time familiarising themselves with the revised Part 4. The provision of supplementary protection by Residual Current Device (RCD) now comes under the heading 'Additional Protection' and the requirements to provide RCDs have been extended.

The Tables in Chapter 41 for earth fault loop impedances are based on a nominal voltage of 230 V (not 240 V), hence the values have been adjusted accordingly. The chapter also includes a new Table 41.5 which gives maximum values of earth fault loop impedance for RCDs.

Chapter 42, Protection against thermal effects now includes the requirements for where particular risks of fire exist (previously in Section 482).Chapter 43, Protection against overcurrent now includes the requirements previously given in Section 473.

Protection against voltage disturbances (Chapter 44) has now been expanded including a new Section 442, 'Protection of low voltage installations against temporary overvoltages due to earth faults in the high voltage system and due to faults in the low voltage system'.

In Part 5, 'Selection and erection of wiring systems' will now include requirements for busbar trunking systems and powertrack systems. Previously, the requirements for protection, isolation, switching, control and monitoring were covered in several different sections of BS 7671. In the 17th Edition, Chapter 53 now includes all the requirements relating to these issues. 'Earthing arrangements and protective conductors', Chapter 54, now incorporates the requirements applicable to equipment with high protective conductor currents which were previously given in Section 607.

RCBO protection - 'serious cost implications':

The requirements relating to cables concealed in a wall or partition less than 50mm deep and are not protected by earthed conduit or have an earthed outer case such as MICC or SWA, are that they must be installed in the prescribed zones. This requirement is almost identical to the requirements of the 16th Edition. However, there has been a further regulation added, which states that these circuits are required to have additional protection by means of a 30mA RCD (in a premise not under the supervision of a skilled or instructed person).

This may have far reaching implications for new installations, additions and alterations. In the majority of new domestic dwellings (depending on the type and method of installation of the wiring system) it may mean that all circuits will require 30mA RCD protection. Other regulations indicate that it would be inappropriate to have a 30mA RCD as the front-end device because of the problem of unwanted and unnecessary tripping. It appears (at this stage), to comply with the requirements of the 17th Edition that you may have to fit Residual Current Circuit-Breakers with Overcurrent Protection (RCBOs) on each circuit. This has a serious cost implication on each installation.

Other equipment:

Chapter 55, 'Other equipment', includes additional requirements to ensure the safe connection of low voltage generating sets, including small scale embedded generators. 'Luminaires and lighting installations', Section 559, gives a new set of requirements for fixed outdoor lighting installations, extra-low voltage lighting installations, lighting for display stands and highway power supplies and street furniture (previously in Section 611).

Parts 6 - 7:

Part 6 'Inspection and testing', the requirements are generally similar to those in BS 7671: 2001. The minimum values of insulation resistance have been increased.

Part 7, 'Special installations or locations', there are significant changes and additions: Section 607 of BS 7671: 2001 relating to high protective conductor current has been incorporated into Section 543. Section 611 of BS 7671: 2001 relating to highway power supplies has been incorporated into Section 559.

Perhaps the area causing much speculation prior to the launch of the 17th Edition is Section 701, relating to locations containing a bath or shower. The requirements have now changed to permit RCD-protected socket-outlets to be installed 3m horizontally beyond the boundary of Zone 1. Zone 3 is no longer defined and supplementary bonding is no longer required, providing the appropriate disconnection times are met, all circuits are protected by RCD and all extraneous conductive parts of the location are effectively connected to the protective main equipotential bonding.

In Section 704, 'Construction and demolition site installations' and Section 705 'Agricultural and horticultural premises,' reduced disconnection times and the 25V equation are no longer included. The requirements relating to caravan parks can now be found in Section 708 and include the requirement that each pitch socket-outlet must be provided individually with overcurrent and RCD protection.

The requirements for electrical installations in caravans and motor caravans are now in Section 721. Part 7 also includes the following new Sections: Section 709 Marinas and similar locations, Section 711 Exhibitions shows and stands, Section 712 Solar photovoltaic (pv) power supply systems, Section 717 Mobile and transportable units, Section 740 Temporary electrical installations for structures, amusement devices and booths at fairgrounds, amusement parks and circuses and Section 753 Floor and ceiling heating systems.

Appropriate changes have been made to Appendices 1 to 7, in particular the methods and tables used in Appendix 4 and there are also several new Appendices.

Log on to www.niceic.com and follow the links to the 17th Edition for up to the minute changes.

How NICEIC can help:

To help NICEIC Approved Contractors and Domestic Installers get a better understanding of the regulations, the organisation are hosting free nationwide seminars on the 17th Edition as part of our added value service, details of which are on the NICEIC website.

NICEIC is also providing information for the wider trade. For those not registered with NICEIC, a useful one day paid for seminar is available to book. These seminars include an overview of BS7671:2008, the reasons for the change, including the harmonization process. It also looks at the changes to the structure of the Standards and a summary of the new sections and regulations along with an explanation of the many important technical changes. Attendees will also receive information about guidance documents, courses and City & Guilds qualifications.

For most contractors, the most suitable way to update their skills will be to attend a 17th Edition City & Guilds course which will be available across the country from January.

NICEIC training courses are available to all electricians, and it has worked closely with City & Guilds over the past six months to ensure the qualifications meet the demand for practical, relevant and up-to-date qualifications for the industry, both for those who want a comprehensive qualification on the 17th and for those who require an update from the 16th to the 17th.

NICEIC has created a range of publications and videos for those electricians who just require an overview of the standard or wish to learn on their own, including 'A Learners Guide to the 17th Edition'. A contractor friendly, cost effective, 17th Edition Toolbox is also available and includes a simplified, accessible and practical guide to the Regulations, a copy of the standard, a 17th Edition DVD and a book of vouchers to redeem against products, insurance and training courses.

In summary, there are comprehensive training courses and publications dedicated to the 17th Edition and, so soon after Part P, NICEIC has consciously made its offering as cost effective as possible. Changes to the Wiring Regulations have occurred over many years and the 17th Edition, phased in gradually from January to July, takes into account harmonization and new technologies.

For more information on NICEIC 17th Edition publications, training or the Contractor Toolbox telephone 0870 013 0382 or visit www.niceic.com.