New 17th Edition

Just to let everyone know that all of our electricians have now completed the new City & Guilds course on the 17th Edition Wiring Regulations and have all passed.

These Regulations were published on January 1st 2008 and come into effect in July 2008. Installations designed before 1st July 2008 can be in accordance
with the 16th Edition IEE Wiring Regulations and installed and certified as such after 1st July 2008. However, all design after 1st July 2008 is required to be to the 17th
Edition IEE Wiring Regulations and installation and certification will have to reflect such.

Introduction to the Changes
BS7671:2001 is the current national standard for all electrical work undertaken in
the United Kingdom. The first edition of BS7671 was published in 1992 and has
so far been amended six times. The 17th Edition is the result of a complete
review of the 16th Edition and aims to standardise the UK standards with the
Harmonised Documents (HD’s) produced by the European Committee for
Electrotechnical Standardisation (CENELEC).
Changes
Preface. A new informative note in the preface advises that publication of the
2008 edition of BS7671 does not automatically mean that installations complying
with previous editions are unsafe for continued use or need to be upgraded.
Numbering. The Regulation numbers are changed so as to be in line with
International Electrotechnical Commission (IEC) Numbers. This enables users to
readily relate UK regulations with European HDs and 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.• The 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 20 A and intended for general use by
ordinary persons must be protected with 30 mA RCDs. This means that
general purpose sockets in domestic and similar properties must have
RCD protection.
• External sockets rated not exceeding 32 A must also have 30 mA
RCD protection.
• Maximum permitted earth loop impedance – Zs values have been adjusted,
based on 230V nominal and this has slightly reduced these, for example for
32amp type ‘B’ MCB protection the maximum permitted is 1.44and was
previously 1.5.
Selection and erection of wiring systems – chapter 52.• An important new regulation that particularly affects domestic and similar
installations, 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 or screws to be protected by a 30 mA
RCD as well as being installed in the ‘safe zones’ created by the position of
accessories etc. as previously permitted.
• Similarly, irrespective of depth of cable, cables that are installed in metal framed
walls require 30 mA 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.
• Maximum permitted volt drop where supplied directly from a public
distribution system is now 3% for lighting and 5% for all other applications.

Luminaires and lighting – section 559• This is a new section applicable to all general lighting installations as appropriate
to particular locations and structures.
• Includes requirements for fixed outdoor lighting including highway power
supplies and street furniture previously in Part 6, and extra low voltage (less
than 50 volts a.c. and 120 volts d.c.) lighting systems.
• Applies to both individual luminaires and multiluminaire track lighting and
similar systems.
• Special considerations for protection against fire.
Inspection and testing – part 6
Minimum permitted insulation resistance values are now 0.5Mfor SELV and
PELV (250Vd.c. test voltage), 1.0Mfor installations up to 500V (500Vd.c. test
voltage) and 1.0Mfor installations in excess of 500V (500Vd.c. test voltage).
Special locations – part 7
Part 7 addresses the particular risks that occur in various special locations. There
are several new sections in Part 7. Many of the existing sections have been
modified in line with the European HD’s.
Modified sections
All of the following Sections have been modified to accommodate the regulations
contained in the European HD’s.
701 – Locations containing a bath or a shower particularly the changes from the
16th Edition are substantial:
• Zones 0, 1 & 2 as defined in the 16th Edition are retained. Zone 3 is
being removed. New regulations require all circuits supplying equipment in
the bathrooms to be protected by 30 mA RCDs.
• Supplementary equipotential bonding is no longer required providing the
main bonding of services within the property is in place.
• SELV (separated extra low voltage) socket outlets and shaver socket outlets
are permitted outside Zone 1. 230 V socket outlets are permitted
provided they are more than 3 metres from Zone 1.
702 – Swimming pools
703 – Rooms and cabins containing sauna heaters
704 – Construction sites
705 – Agricultural and horticultural premises
706 – Conductive locations with restricted movement
707 – Previously 607 in the 16th edition is not used. The particular requirements
are embodied in the General Earthing Requirements of Chapter 54.
708 – Caravan and Camping Parks 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, each pitch socket outlet is to have separate 30 mA
RCD protection.
New sections
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