BS 7671:2008 The Changes from the 16th Edition
Below are are a summary of the Changes from 16th Edition as detailed in the ECA’s 17th Edition factsheets. You can view or download PDF versions from the electricians forums website.
This article may be useful to both those who are new to BS7671 as well as those familiar with the 16th Edition.
The following list of changes gives the reader a good idea of the scope and direction of the new BS7671:2008.
These Regulations came into effect in July 2008.
BS7671:2008 is the result of a complete review of the 16th Edition and is the current national standard for all electrical work undertaken in the United Kingdom.
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 Electro technical Commission (IEC) Numbers.
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
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 1.44Ω and was
previously 1.5Ω.
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 are made for protection against fire.
Inspection and testing – part 6
Minimum permitted insulation resistance values are now 0.5MΩ for SELV and
PELV (250Vd.c. test voltage), 1.0MΩ for installations up to 500V (500Vd.c. test
voltage) and 1.0MΩ 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 has been 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 and 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
This article is intended as an overview of the changes and not an authoritative guide to BS7671:2008.
The following qualifications deal with this subject matter in detail.are:
City & Guilds 2382 17th Edition Wiring Regulations BS7671:2008
City & Guilds 2382 17th Edition Wiring Regulations BS7671:2008 Update
City & Guilds 2391 Inspection, Testing & Certification of Electrical Installations
Courses are widely available throughout the country.
For further information on Elecsa & ECA courses visit http://www.elecsa.org.uk/downloads/17th%20Edition%20brochure%202009.pdf or contact enquiries@elecsa.co.uk
Sources of information:
BS 7671- Requirements for Electrical Installations
Electrician’s Guide to the Building Regulations
electriciansblog.co.uk
{ 1 comment… read it below or add one }
Electrical sockets have been provided immediately behind taps within a refurbished
Food Technology Room – the contractor has advised that this is within the 17th Amendment, comments please.