BS7671:2008 The Changes.

by Steve on March 29, 2009

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

On-Site Guide

Electrician’s Guide to the Building Regulations

 electriciansblog.co.uk

{ 1 comment… read it below or add one }

A Johnson July 20, 2011 at 09:56

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.

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