Voltimum Managing Editor James Hunt looks - in this VoltiBULLETIN - at the 17th Edition in brief one year on from it being implemented and how it has fared in terms of electrical contractor understanding:
The 17th Edition was published in January 2008 and was fully implemented on July 1st that year. One year one, how has it fared? Has it been accepted by electrical contractors and installers? Have they had trouble understanding it and it's implications? How have the wiring accessory and test instrument manufacturers addressed the issue? In fact, did they need to at all?
But first, we need a brief resumé of the 17th Edition and its most important points.
The introduction of the 17th Edition has affected electrical installation practise throughout the UK and Northern Ireland, and will also have had an effect on the Republic of Ireland, which published its own Fourth Edition of the National Rules for Electrical Installations, ET101: 2008 last October. The rationale behind both is mainly to do with international harmonisation of the document with European standards - eg: wiring rules in IEC and CENELEC.
Therefore, the 17th Edition has adopted the IEC numbering system, and its layout and parts have been completely revised. For example, many of the chapters have been completely rewritten. The current Part 6 (Special Locations) has become Part 7 to align with IEC. The 17th Edition also includes extra sections on Special Locations not previously included in BS 7671, and the existing Special Locations have been revised to align with changes in CENELEC harmonisation documents.
The main points:
In brief, the salient points of the 17th Edition are:
- Added requirements to protect against voltage disturbances
- To implement measures against electromagnetic influences, and for emergency escape lighting and fire protection
- A new concept of protection
- All socket-outlets up to 20A in homes now require 30mA RCD protection
- Socket-outlets up to 32A for mobile equipment for use outdoors will require 30mA RCD protection.
- Extra requirements for the connection of low voltage gensets including SSEGs
- A new series of regulations concerning lighting installations.
- Changes been made to the requirements for insulation resistance
- Changes to locations containing a bath or shower, and other Special Locations.
The 16th Edition has now been phased out and all electrical installations affected must conform to17th Edition requirements.
The changes and their impact:
The 17th Edition has affected every electrical contractor and installer working in the UK, and it marks another major change to the way electricians work. How have they coped?
Probably the single most important change in the 17th Edition - especially in terms of the domestic sector - is the requirement for additional protection by the use of RCDs, or RCBOs. These now need to be provided to nearly all circuits within dwellings - at least, all those for use by 'ordinary persons' i.e. a person who is not a 'skilled' or 'instructed' person.
These are significant changes, so how have electrical contractors tackled them? Firstly, clued up contractors quickly noted that the Regulations are open to some interpretation in places. For example, one contractor we spoke to said: "The regulations are open to some interpretation. Provided that you can put a strong argument for an aspect, then I think there are several options.
"The main issue for me early on concerned when the installation was designed. If it was a new build, then I considered a fully integrated consumer unit. If it was an alteration, then a decision had to be made about how, retrospectively, the installation needed to comply with the 17th Edition, because if the job was started before the 17th Edition was fully implemented, it could comprise a mixture of 16th and 17th Edition interpretations."
This contractor thought that there were likely to be many installations having RCD spur connection units supplying additional socket outlets, and with many 'bolt-on' RCD enclosures adjacent to consumer units. This would be expensive and, in any case, he thought that having RCD wall sockets (SRCDs) does not protect the cable between consumer unit and socket. Another contractor contacted had come to the same conclusion, saying: "There is some room for various interpretations in the 17th Edition. We do this where necessary, but we never install RCD protected spur units as they often look ugly, which householders don't like. More importantly, the cable to the consumer unit is not protected, so there's a safety concern." He added that he uses RCDs everywhere inside spilt-load consumer units. He would prefer to use RCBOs but they are, he said, too expensive for most applications, certainly domestically.
To minimise nuisance tripping, another contractor said that he tended to use RCBOs on individual circuits, but he thought that a new installation might have problems with dishwasher/washing machines that could constantly trip the RCD at the heating stage. For commercial work, he said that his main problems concerned older style distribution panels, it being not easy to obtain RCBO modules as direct replacements for older 3871 style MCBs. He also wondered whether the mandatory use of RCDs means that some installers might worry less about cable depths and safe zones/route considerations, because if there was proper RCD protection provided, then the rest of the cabling would be covered and, therefore, might not receive the consideration it deserves.
The second contractor also thought that the 50mm depth requirement for cables buried in walls is too much for most houses, without causing serious damage, so he still has to use RCDs. He said that it is only commercial or industrial work that accepts surface-mounted cable management solutions.
Testing to the 17th Edition:
All electrical installations must now be inspected, tested and certificated to the 17th Edition.
The 17th Edition does not vary greatly from the now defunct 16th Edition, but the changes in terminology, numbering system and additional requirements should be considered. In finding your way around, Part 6 contains electrical installation inspection and testing requirements, plus 'competency' references (see note1).
Regulations 610.5 (initial verification) and 621.5 (periodic inspection and testing) aim to ensure that those carrying out work should be 'competent'. Regulation 631.4 requires Electrical Installation Certificates, Periodic Inspection Reports and Minor Electrical Installations Works Certificates to be produced and authenticated by 'competent person(s)'.
Chapter 61 covers Initial Verification (inspection/testing of new electrical installation work), plus required inspections preceding testing. Chapter 62 covers Periodic Inspection and Testing for existing installations, while Chapter 63 covers Certification and Reporting. Note that Regulation 134.2.2 requires the installation designer to recommend when the first periodic inspection is to be carried out.
The only real alteration concerns insulation test limits for SELV, PELV and systems operating at less than 500V. For operating voltages up to 250V, a minimum insulation resistance of 0.5MO is now required, compared with 0.25MO previously. For operating voltages up to 500V, the minimum insulation resistance will be 1MO, rather than 0.5MO. There are no changes for continuity and RCD testing.
Any instruments providing fixed pass/fail indication for insulation tests on the basis of the old 16th Edition values need adjustment to take into account new values. Almost always, however, existing test equipment can be used, as long as it meets safety and specification requirements. It is important to be clear that, as long as electrical contractors own testers that comply with the 16th Edition that are in good order, they are suitable for all work to the 17th Edition. There is a lot of confusion about this but, as far as test instruments are concerned, nothing has changed - though Fluke's Ken West has noted that 'measuring instruments and monitoring equipment should be chosen to meet the requirements of the relevant parts of BS EN 61557, the standard covering electrical test instruments. Where such equipment does not meet the requirements of this Standard, it must provide no less performance and safety'.
1Note that for NICEIC schemes, ONLY the Approved Contractor or Domestic Installer responsible for the work can issue an NICEIC certificate for that work, irrespective of the responsibility for the design and inspection and testing of the work.
The IEE's view:
VoltiBULLETIN spoke with the IEE's Geoff Cronshaw, asking him how the 17th Edition had fared over the year since implementation. He said that it had generally gone well, with little negative feedback from electrical contractors and installers. He felt that "it has all settled down nicely, with contractors generally working very happily with it, although some had been concerned about alterations and additions to domestic installations, such as adding a few extra sockets/switches etc requiring the fitting of expensive RCDs or RCBOs to meet 17th Edition requirements.
This was echoed by some contactors who have had concerns about older installation repairs and updates. They said that it can be difficult to tell elderly people that they must have the latest safety equipment fitted at considerable cost to enable their existing installations to meet the latest regulations. Geoff Cronshaw said that a working group is looking into this aspect of the 17th Edition.
As far as amendments are concerned, Geoff Cronshaw said that none have been issued and none were planned for the moment, though there is a small corrigenda - for this, see elsewhere in this VoltiBULLETIN.
The 17th Edition is available as a 360-page paperback (code: PWR05060), priced £65. However, if you have booked on a 17th Edition course with the IET, you are entitled to a 20% discount taking the price to £52. Call the IET on 01438 767 328, or go to www.theiet.org.
More on the 17th Edition:
To see more on the 17th Edition, please click on the links below:
'Competent persons' in terms of the 17th Edition and Part P - Voltimum UK managing editor James Hunt reiterates 'competent person' definitions (17th Edition, and also for Part P of the Building Regulations - the definitions are different).
Testing to the 17th Edition - All electrical installations must now be inspected, tested and certificated to the 17th Edition.
17th Edition corrigendum - The 17th Edition corrigendum is the only change so far in this Edition's one year history. In fact, it shows not changes to the 17th Edition but minor corrections to it.
Future developments in the IEE Wiring Regulations - Geoff Cronshaw provides an overview of planned future developments in the IEE Wiring Regulations BS 7671:2008, in this article originally published in its own publication, 'Wiring Matters'.
Provision of information within BS 7671 - Jon Elliott of the IET explains the requirements for provision of information and documentation within BS 7671: 2008 in this article originally published in the IET's Wiring Matters magazine.
Are cable verifications being carried out in line with the 17th Edition? - On the first anniversary of the 17th Edition of the IEE Wiring Regulations, Dr. Jeremy Hodge, Chief Executive of BASEC, comments on worries about certain non-compliant cables in relation to the 17th Edition.
A consumer unit to make installers' lives easier with the 17th Edition - On the first anniversary of the adoption of the 17th Edition Wiring Regulations, which forced a major rethink on circuit protection, Legrand's marketing director, Louis-Benoit Rusterholtz, explains how the company has adapted its consumer units to meet changed requirements.
Schneider Electric extends consumer units range - Square D, a brand of Schneider Electric, is enhancing its Domae and Qwikline ranges of consumer units to offer installers and wholesalers greater options when choosing high quality products that meet 17th Edition regulations.