The key changes

Preface

A new informative note in the preface advises that publication of the 2008 edition of BS7671 does not automatically mean installations complying with previous editions are unsafe for continued use or need to be upgraded.

Numbering

The regulation numbers are changed to align with IEC numbers. This enables users to readily relate UK regulations to European Harmonised Documents (HDs) and International Electrotechnical Commission (IEC) regulations.

Fundamental principles

Requirements are added for protection for persons and livestock against injury, and property against damage caused by voltage disturbances and electromagnetic influences.

Protection against electric shock – Chapter 41

This chapter has been rewritten. Many regulations are worded differently but the requirements are not significantly changed.

The terms “direct contact” and “indirect contact” are no longer used. They are replaced with “basic protection” and “fault protection”. Basic protection is protection against touching live parts. Fault protection is protection against receiving a shock from conductive parts that have become live due to a breakdown of insulation or damage to equipment.

Socket outlets rated not exceeding 20A and intended for general use by ordinary persons must be protected with 30mA RCDs. This means that general purpose sockets in domestic and similar properties must have RCD protection.

External sockets rated not exceeding 32A must also have 30mA RCD protection.

Selection and erection of wiring systems – Chapter 52

An important new regulation that particularly affects domestic and similar installations. It requires cables that are buried less than 50mm into a wall or partition, and are not enclosed in earthed metallic covering or have mechanical protection capable of resisting nails, screws or drills, to be protected by a 30mA RCD as well as being installed in the “safe zones” created by the position of accessories etc as previously permitted.

Similarly, cables that are installed in metal framed walls require 30mA RCD protection if not otherwise protected by earthed metallic covering.

The above requirements do not apply to installations that are under the control of skilled or instructed persons, such as office buildings, large retail outlets and industrial premises.

Other equipment Chapter 55

Generator sets 55 – Section 551.2

This section contains requirements that are applicable to low voltage electricity generating sets, including wind turbines, solar-powered generators, pv systems (also covered in Section 712), water turbines and combined heat and power for use in domestic and commercial installations. The use of this equipment is expected to escalate in the next few years, which means that an understanding of this section will become important.

Luminaires and lighting – Section 559

This is a new section applicable to all general lighting installations as appropriate to particular locations and structures. It includes:

• Requirements for fixed outdoor lighting including highway power supplies and street furniture previously in Part 6, and extra low voltage (less than 50V ac and 120V dc) lighting systems.
• Both individual luminaires and multi-luminaire track lighting and similar systems.
• Special considerations for protection against fire.

Special locations – Part 7

Part 7 addresses the particular risks that occur in various special locations. Many of the existing sections have been modified in line with the European HDs:

• 701 Locations containing a bath or a shower

The changes from the 16th Edition are particularly substantial here. Zones 0, 1 and 2 as defined in the 16th Edition are retained. Zone 3 is removed. New regulations require all circuits supplying equipment in the bathrooms to be protected by 30mA RCDs.

All cables buried in walls surrounding bathrooms, regardless of the points they are serving, have to be protected by 30mA RCDs.

Supplementary bonding between metallic service and waste pipes and the earth connections of equipment is no longer required providing the main bonding of services within the property is in place and the metallic pipework can be proved by testing to be continuous. This means green and yellow cables in bathrooms are unlikely to be necessary.

SELV (separated extra low voltage) socket outlets and shaver socket outlets are permitted outside Zone 1. And, 230V socket outlets are permitted provided they are more than 3m from Zone 1.

• 702 Swimming pools

Zones A, B and C have been replaced by Zones 0, 1 and 2. Scope now includes basins of fountains.

• 703 Rooms and cabins containing sauna heaters

Zones A, B, C and D replaced with Zones 1, 2 and 3.

• 704 Construction sites and 705 Agricultural and horticultural premises

In both the above sections the reduced connection time of 0.2s and the 25V equation have been removed.

• 706 Conductive locations with restricted movement
• 707 Previously 607 in the 16th Edition

This is not used. The particular requirements are embodied in the General Earthing Requirements of Chapter 54.

• 708 Caravan and camping parks

This was formerly caravans, motor caravans and caravan parks in the 16th Edition. The section is now divided into Section 708 and Section 721 Caravans and Motor Caravans. Of particular note is the fact that each pitch socket outlet is to have separate 30mA RCD protection.

There are also several new sections in Part 7 including:

• 709 Marinas and similar locations
• 711 Exhibitions, shows and stands
• 712 Solar photovoltaic (pv) power supply systems
• 717 Mobile or transportable units
• 721 Caravans and motor caravans
• 740 Temporary electrical installations for structures, amusement devices and booths at fairgrounds, amusement parks and circuses.