Blue is the colour

The revised version will be called BS 7671: 2001 – IEE Wiring Regulations 16th Edition. Don't be caught out by this; although the version is now BS 7671: 2001, it is still known as the IEE Wiring Regulations 16th Edition. It will be less confusing if, as per previous editions, it is referred to by its colour.

Implementation
The 1 June publication date may slip, however the IEE has stated that the document will definitely be released in June; keep your eye on the IEE's web site at www.iee.org.uk for an exact date.

BS 7671: 2001 must be implemented for new designs starting on or after 1 January 2002. As with previous versions, the document may be optionally used or specified before that date.

It should be noted that it is possible to have a building design, for example, currently on your CAD system, that won't be completed for say five years. This installation will be certified to the yellow book.

The changes
The majority of changes to BS 7671 have come about to correspond with various CENELEC harmonised documents (HDs). The list of HDs that BS 7671: 2001 aligns with is published in the preface to the document. Most parts of the standard are now regulated with HD 384, which is used as an alignment document for all of the CENELEC countries.

Major revisions have been made to the following parts:

• Part 1 – scope;
• Section 601 – bathrooms;
• Section 607 – high earth leakage currents;
• Chapter 74 – certification and reporting.

• Chapter 44 – atmospheric switching and overvoltage;
• Chapter 48 – choice of protective measure in fire risk situations.

Part 1 has had extensive new sections added to align with respective parts in HD 384 (130 – safety; 131 – design; 132 – section of electrical equipment; and 133 – verification).

There is nothing particularly new in these regulations as the requirements in nearly all cases were included in the general body of the yellow version. It could be viewed that being in the fundamental part 1 now additionally reinforces the requirements in the general regulations. This will not make any difference to most designers and contractors, but those who needed to refer to Part 1 of the yellow book are now advised to read and compare the revised Part 1 in the blue book.

The latest revision to BS 7671 has taken the opportunity to correct some problems in Section 601 discovered in the third amendment.

The common rules section (601-06-01) has been modified to allow shaver supply units to be installed in zone 2 areas within a bathroom. They must however be located only "where direct spray from showers is unlikely".

A little commonsense applied to this regulation means that it is really quite useful and allows shaver supply units to be located in many areas in Zone 2 that were prohibited by the third amendment. It means that we do not have to note shaver outlets on a periodic inspection report for an existing bathroom where they are not in a position likely to be splashed (which is, in practice, most positions).

The wording of the regulations concerning local supplementary equipotential bonding within bathrooms has been improved upon and now reads: "local supplementary equipotential bonding complying with 547-03 shall be provided, connecting together the terminals of the protective conductors of each circuit supplying class I and II equipment in zones 1, 2 or 3 and extraneous- conductive- parts in these zones."

The improved clarity of the above wording removes many of the ambiguities present in the third amendment wording. It is now clear that one bond is required (to extraneous-conductive-parts) for each circuit in a bathroom. If there are no electrical circuits, then no bonding is required. If there is no extraneous-conductive-part, then no bonding is required. Only one bond per circuit is required (not one for each outlet).

Section 607 – high leakage protective conductor currents – has been totally redrafted for BS 7671: 2001.

Since the introduction of the existing section 607 some years ago, confusion has reigned in many areas of the industry. The main problem has been with the design of socket-outlets circuits, where, to comply with section 607, knowledge of the equipment likely to be plugged was required.

This has obvious problems, and designers were faced with either guessing, sticking to standard circuitry or defaulting to section 607 designs.

With BS 7671: 2001 there is good and bad news on this front. A knowledge, estimate or guess of equipment that the client is likely to use on the circuit is still required.

However, after careful scrutiny of the new regulations, the circuit design requirements have changed – they have been made simpler. Duplicate terminals are still required at distribution boards, junction boxes and socket-outlets, but section 607 states that cpcs complying with section 543 will be large enough for compliance with section 607. Thus, if you have got 1·5 mm (or even 1 mm) it will satisfy the new section 607 as long as it is duplicated in separate terminals at distribution boards, junction boxes and socket-outlets. For smaller and domestic installations, twin and earth cables can be utilised for compliance with section 607.

The new chapter 44 is concerned with measures of protection against overvoltage due to both atmospheric or switching origins.

On inspection of the new chapter, it first appears that there would be some work to do to comply with its content (ie fitting of surge protective devices). However on closer reading, the key to the additional measures is whether the installation is in an area which receives more than 25 thunderstorm days per year. This does not apply to the UK (it may apply where BS 7671: 2001 is used abroad).

The other measure in this section is a table of a voltage impulse withstands (table 44A), but equipment manufactured to BS EN standards will comply with these. Therefore, if equipment complying with BS EN standards is used, chapter 44 can effectively be ignored.

Chapter 48 – precautions where risk of fire exist – is again a new section. This makes new requirements for electrical installations in locations where stored flammable materials are present (in factories, for example) and in locations where combustible construction is used.

The section for stored materials only need apply to industrial applications, but the section on combustible construction is not as well defined and some may interpret it to include domestic construction. However, as it restricts the use of cables to those of a non flame-propagating type, it appears that they were not meant to apply to domestic installations. At the time of writing this problem remained unresolved.

This gives a summary of what you can expect when the blue book is published in June. Due to the complexity and style of drafting of BS 7671:2001, designers, installers and those responsible for inspection and testing will have to obtain and read the blue book and carefully consider the amendments. IEE Guidance Note revisions will follow the general publication of the main document. The ECA will be holding awareness seminars in the autumn (see box 'Revisions in brief').

At least the main publication should not change for another three years!