IET advises on wiring regulations
Geoff Cronshaw (pictured), Chief Electrical Engineer at the IET, on the recently launched IET Wiring Regulations, 17th Edition, BS 7671:2008 incorporating Amendment No 1: 2011.
The Institution of Engineering and Technology (IET, formerly the IEE) has launched the IET Wiring Regulations, 17th Edition, BS 7671:2008 incorporating Amendment No 1: 2011. Jointly published with BSI, the amended IET Wiring Regulations sets the standard for all new electrical installations in the UK.
Here, Geoff Cronshaw, Chief Electrical Engineer at the IET, highlights the key changes – which come into effect on 1st January 2012 – and which are highly relevant to anybody working within the electrical industry, particularly those involved in the wholesale market and more so - the design, erection and verification of electrical installations.
Background to the new regulations
The amended Wiring Regulations, BS 7671:2008(2011) is based on CENELEC HDs and IEC standards, i.e. those of Europe and of the international community. The standardisation process is perpetual and standards are continually evolving requiring national standards bodies to incorporate the technical changes. Therefore, the amended Wiring Regulations embody the most recent changes made at a European and International level.
One of the major changes which those working within the electrical product field should be aware of is Appendix 6 which introduces the new Electrical Installation Condition Report to replace the Periodic Inspection Report. In addition, a number of new sections have been added which are also relevant. These relate to electromagnetic disturbances, devices for protection against overvoltage, and operating and maintenance gangways. This article outlines these key changes.
Changes to the Periodic Inspection Report
The Electrical Installation Condition Report (EICR) has replaced the Periodic Inspection Report. The model forms to be issued for reporting have also changed. The change from the Periodic Inspection Report to the Electrical Installation Condition Report (EICR) represents a major shift from the 17th Edition of the Wiring Regulations. The new report, both in terms of its content and name, is felt to be more descriptive than the previous Periodic Inspection Report.
Within the EICR, new codes and definitions have been developed with the intention of being clearer. For example, within the observations section the four codes of the old PIR: 1 (requires urgent attention), 2 (requires improvement), 3 (requires further investigation), 4 (does not comply with BS 7671:2008 amended to…) have been replaced by three codes. These are code 1 danger present (e.g. bare live wires which can easily be touched), code 2 potentially dangerous (e.g. RCD will not operate correctly when tested), code 3 improvement recommended (e.g. no 30 mA RCD for additional protection for socket-outlets used by non-skilled/non-instructed persons). Under this new coding system a summary of the condition of the installation in terms of safety should be clearly indicated in Section E of the condition report.
Section 444 – Electromagnetic disturbances
This is an entirely new section brought about by developments in CENELEC - HD 60364-4-444 Measures against electromagnetic disturbances. In 1996, the EMC Directive (89/336/EEC) was issued requiring electromagnetic compatibility of products being sold across Europe. The Directive relies on harmonised standards to which products are to comply; the CE mark, for example, is a direct result of the work undertaken to remove trade barriers and, hence, allowed development of the EMC Directive. In 2004, the EMC Directive was modified as 2004/108/EC and came into force in July 2007; the main change was the inclusion of fixed installations.
Therefore, Section 444 has been developed to provide the basic requirements and recommendations to enable the avoidance and reduction of electromagnetic disturbances and meet the Directive. The section includes guidance for the location and sources of electromagnetic disturbances relative to the positioning of other equipment as well as measures for minimising electromagnetic disturbances.
Section 534 – Devices for protection from over voltage
This is a new section which has been implemented by CENELEC in HD 60364-5-53. A surge protective device (SPD) is a device that is intended to limit transient over voltages and divert damaging surge current away from sensitive equipment. Equipment is now more precise with little tolerance on the components, hence, less robust than it ever was, making SPDs more important than ever.
SPDs must have the necessary capability to deal with the current levels and durations involved in the surges to be expected at their point of installation. SPDs can operate in one of two ways, based on the component technologies within them.
One way is as a voltage switching device where under normal conditions, the device is an open circuit, but at a certain threshold voltage the SPD conducts and diverts the current through it. It has two states, ON and OFF, hence the name of voltage switching.
Another way is as a voltage limiting device. Voltage limiting type SPDs again present an open circuit under normal circuit conditions. When an overvoltage is detected the device begins to conduct, dropping its resistance dramatically such that the overvoltage is limited and the surge current is diverted away from the protected equipment.
Section 534 gives detailed requirements on the selection, connection, installation and co-ordination of Surge Protection Devices.
Section 729 – Operating and maintenance gangways
Section 729 is intended to ensure a safe working environment for skilled or instructed persons working in areas such as switchrooms and controlgear assemblies where, historically, not much space has been allocated. The Section has been incorporated into Amendment Number 1 in order to align with the European Harmonised Document. Regulation 15 of the Electricity at work Regulations requires that adequate working space, means of access and lighting shall be provided at all electrical equipment on which, or near which, work is being done.
The Section sets out minimum requirements for the provision of adequate working space, means of operational and emergency access and evacuation at, or near, electrical equipment which is being worked on. The amended regulations outline new requirements that the width of gangways and access areas shall be adequate for work, operational access, emergency access, emergency evacuation and for the movement of equipment.
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