CGLI 2330 Certificate in Electrotechnical Technology Level 2 Installation Technology: Unit 205 – Installation (Buildings & Structures)
Unit 01 - Statutory and Non-Statutory Requirements
Statutory & Non-Statutory Requirements Unit Aims By the end of the unit participants should be able to:
State how specific sections/topics within BS7671 impact upon electrical installations within buildings and structures a) selection and erection of equipment b) isolation and switching c) inspection and testing d) protection against fire e) protection against electric shock f) protection against overcurrent g) Special Locations (Syllabus Reference: 4.1.03)
State how data from the following may be used to support electrical installations a) BS7671 b) IEE Guidance Notes c) IEE On Site Guide (Syllabus Reference: 4.1.04)
State how BS7671 regulatory requirements may impact upon the electrical installation process on-site (Syllabus Reference: 4.1.05)
State the need for statutory regulation of given hazardous installations a) potentially explosive atmospheres b) storage and delivery of petroleum (Syllabus Reference: 4.1.06)
Outline the requirements of Codes of Practice relevant to specific systems a) Earthing b) lightning protection (Syllabus Reference: 4.1.07)
State the purpose/function of a device or item of equipment identified by a BS or BSEN number within BS7671 (Syllabus Reference: 4.1.08)
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Unit 01 Page 1
August 2011
CGLI 2330 Certificate in Electrotechnical Technology Level 2 Installation Technology: Unit 205 – Installation (Buildings & Structures)
Unit 01 - Statutory and Non-Statutory Requirements
Statutory & Non-Statutory Requirements BS7671 – The IET Regulations The Institution of Engineering and Technology (IET) “Requirements for Electrical Installations” are non-statutory regulations. They relate principally to the design, selection, erection, inspection and testing of electrical installations, whether permanent or temporary, in and about buildings generally and to agricultural and horticultural premises, construction sites and caravans and their sites. Paragraph 7 of the introduction to the Electricity at Work Regulations says, “the IET Wiring Regulations is a code of practice which is widely recognised and accepted in the United Kingdom and compliance with them is likely to achieve compliance with all relevant aspects of the Electricity at Work Regulations”. The IET Wiring Regulations only apply to installations operating at a voltage up to 1 000 volts a.c. They do not apply to electrical installations in mines and quarries where special regulations apply because of the adverse conditions experienced there. BS7671 is divided into a number of Parts and Chapters as shown in the chart on the following page: Numbering System It is preferable to consider BS7671 in three parts:
The regulations
The appendices and
The tables
The Regulations The Regulations use a numbering system to identify individual regulations. This is in line with the system used in the European harmonisation documents and that adopted by European countries generally. You will need to have available a copy of the 17th Edition of BS7671 in order to work through the following exercise. For example: Regulation number 412.2.2.4 [4]12.2.2.4 [41]2.2.2.4 [412].2.2.4 [412.2].2.4 [412.2.2].4 [412.2.2.4]
Part 4 – Protection for Safety Chapter 41 – Protection Against Electric Shock Section 412 – Protective Measure: Double or reinforced insulation Group of Regulations: Requirements for basic protection and fault protection Sub-group of Regulations: Enclosures The actual Regulation
The Appendix There are fifteen sets of appendices in BS7671. Most of the appendices use tables to convey the information. Appendix 4 is the best example as this contains the current carrying capacity tables.
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Unit 01 Page 2
August 2011
CGLI 2330 Certificate in Electrotechnical Technology Level 2 Installation Technology: Unit 205 – Installation (Buildings & Structures)
Unit 01 - Statutory and Non-Statutory Requirements BS7671: Requirements for Electrical Installations - Layout Part 1
Part 2 Part 3
Part 4
Part 5
Part 6
Part 7
Appendices
Scope, object & fundamental principles Chapter 11 Scope Chapter 12 Object & effects Chapter 13 Fundamental principles Definitions Assessment of general characteristics Chapter 31 Purpose, supplies and structure Chapter 32 Classification of external influences Chapter 33 Compatibility Chapter 34 Maintainability Chapter 35 Safety services Chapter 36 Continuity of service Protection for safety Chapter 41 Protection against electric shock Chapter 42 Protection against thermal effects Chapter 43 Protection against overcurrent Chapter 44 Protection against voltage disturbances and electromagnetic disturbances Selection and erection of equipment Chapter 51 Common rules Chapter 52 Selection and erection of wiring systems Chapter 53 Protection, isolation, switching, control and monitoring Chapter 54 Earthing arrangements and protective conductors Chapter 55 Other equipment Chapter 56 Safety services Inspection and testing Chapter 61 Initial verification Chapter 62 Periodic inspection and testing Chapter 63 Certification and reporting Special installations or locations Section 700 General Section 701 Locations containing a bath or shower Section 702 Swimming pools and other basins Section 703 Rooms and cabins containing sauna heaters Section 704 Construction and demolition site installations Section 705 Agricultural and horticultural premises Section 706 Conducting locations with restricted movement Section 708 Electrical installations in caravans/camping parks and similar locations Section 709 Marinas and similar locations Section 710 Medical locations Section 711 Exhibitions, shows and stands Section 712 Solar photovoltaic (PV) power supply systems Section 717 Mobile or transportable units Section 721 Electrical installations in caravans and motor caravans Section 740 Temporary electrical installations for structures, amusement devices and booths at fairgrounds, amusement parks and circuses Section 753 Floor and ceiling heating systems 1. British Standards to which reference is made in the Regulations 2. Statutory Regulations and associated memoranda 3. Time/current characteristics of overcurrent protective devices and RCDs 4. Current-carrying capacity and voltage drop for cables and flexible cords 5. Classification of external influences 6. Model forms for certification and reporting 7. Harmonized cable core colours 8. Current-carrying capacity and voltage drop for busbar trunking and powertrack systems 9. Definitions – multiple source, d.c. and other systems 10. Protection of conductors in parallel against overcurrent 11. Effect of harmonic currents on ... Moved to Appendix 4 secs 5.5 and 5.6 12. Voltage drop in consumers‟ installations Moved to Appendix 4 secs 6.4 13. Methods for measuring the insulation resistance/impedance of floors and walls to earth or to the protective conductor system 14. Measurement of earth fault loop impedance: consideration of the increase of the resistance of conductors with increase of temperature 15. Ring and radial final circuit arrangements, Regulation 433.1 16. Devices for protection against overvoltage.
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August 2011
CGLI 2330 Certificate in Electrotechnical Technology Level 2 Installation Technology: Unit 205 – Installation (Buildings & Structures)
Unit 01 - Statutory and Non-Statutory Requirements Tables Tables found in the Regulations take their number from the Chapter they relate to. This means that the table number starts with two digits followed by a further number. For example Table 41.2 is found in Chapter 41 of Part 4. [4]1.2 [41].2 [41.2]
Part 4 Chapter 41 The second set of tables in Chapter 41
Tables found in the Appendices take their number from the Appendix number they are in. The table number in this case starts with a single digit followed by a letter and then a number and so on. Table 4D1A. [4]D1A [4D]1A [4D1]A [4D1A]
Appendix 4 Fourth group of tables in Appendix 4 First table in this subgroup The actual table number
Relationship between BS7671 and the Electricity at Work Regulations It is important to remember that there is a relationship between these two sets of Regulations, the latter of which is „statutory‟. Although BS7671 is „non-statutory‟, compliance with them is generally considered as meeting all the requirements of the Electricity at Work Regulations; this is the reason why so much emphasis is placed on BS7671. Electricity at Work Regulations Systems, work activities and protective equipment Strength and capability of electrical equipment Adverse and hazardous environments Insulation, protection and placing of conductors Earthing and other suitable precautions Integrity of reference conductors Connections Means of protecting from excess current Means of cutting off the supply and for isolation Precautions for work on equipment made dead Work on or near live conductors Working space, access and lighting Persons to be competent to prevent danger and injury
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BS7671 (IET Wiring Regulations Part 1 and Part 3 Part 1 and Part 5 Part 1 and Part 7 Part 1 and Part 5 Part 1, Part 4 and Part 5 Part 4 and Part 5 Part 1, Part 5 and Part 7 Part 1 and Part 4 Part 1, Part 4 and Part 5 Part 1, Part 4 and Part 5 Part 1 Part 1 and Part 2
August 2011
CGLI 2330 Certificate in Electrotechnical Technology Level 2 Installation Technology: Unit 205 – Installation (Buildings & Structures)
Unit 01 - Statutory and Non-Statutory Requirements
IET On Site Guide The Regulations themselves are primarily for use by design engineers. For everyday reference, electricians make use of the „On Site Guide‟ which is a condensed version of the Regulations covering the more usual day-to-day aspects of electrical installation. Methods of calculating such things as basic cable selection, conduit/trunking capacities, etc. can be done using the On Site Guide. It must be borne in mind however that the calculations are not as accurate as BS7671 and, because they must err on the side of safety, may result in, for example, larger cables than necessary being selected.
Guidance Notes The IET also publish a range of Guidance Notes on specific topics in which the requirements of the Regulations relating to that topic are appropriately grouped and also to provide clarification on how to interpret the Regulations pertaining to that topic. For example, Guidance Note 3 looks at all aspects relating to Inspection and Testing.
Hazardous Environments BS7671 applies to virtually all electrical installations but some situations require additional (statutory) Regulations to ensure that these potentially hazardous environments do not result in dangerous situations arising. For example, where a potentially hazardous atmosphere exists, e.g. floor mills, flammable gases, etc., it is necessary to ensure that, for example, a spark from an electric switch does not ignite that atmosphere. Additionally, where petrol is stored or delivered, for the same reasons, special requirements are required to ensure the chances of the petrol igniting being greatly reduced and preferably eliminated.
Earthing and Lightning Protection BS6651: (1999) „Code of practice for protection of structures against lightning‟ provides guidance on the design of systems for the protection of structures against lightning and on the selection of materials. Recommendations are made for special cases such as explosives stores and temporary structures, e.g. cranes and spectator stands constructed of metal scaffolding. Guidance is also given on the protection of electronically stored data. The principle informing all the provisions of this British Standard is that of the 'Faraday cage' form of lightning protection, and installations employing alternative technologies fall outside the scope of this British Standard. For more information see pages 312 to 318 of „Electrical Installations Level 2 2330 Technical th Certificate‟ – revised for the 17 Edition IEE Wiring Regulations (ISBN 978 0 435401 09 2).
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August 2011