City & Guilds Electrical Installation (Level 3) BS 7671 Wiring Regulations and Special Installations Syllabus

BS 7671 Wiring Regulations and Special Installations syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for BS 7671 Wiring Regulations and Special Installations in City & Guilds Electrical Installation (Level 3), not a summary of it.

1. 1

   Structure and Application of BS 7671

   4 topics

   • Scope and structure of the Regulations
     • Parts, chapters and appendices
     • Relationship with statutory law and guidance
   • Fundamental principles (Part 1 and 13)
     • Protection for safety
   • Assessment of general characteristics (Part 3)
     • Maximum demand and supply characteristics
     • External influences classification
   • Using tables and appendices effectively
2. 2

   Selection and Erection Requirements

   4 topics

   • Common rules (Chapter 51)
     • Operational conditions and external influences
     • Identification and notices
   • Wiring systems requirements (Chapter 52)
     • Current-carrying capacities and methods
   • Protection, isolation and switching (Chapters 53/46)
     • Devices for isolation and switching
     • Emergency switching and functional switching
   • Earthing and protective conductors (Chapter 54)
3. 3

   Special Locations and Installations (Part 7)

   4 topics

   • Locations with bath or shower (Section 701)
     • Zones and equipment selection
     • Supplementary bonding requirements
   • Swimming pools and saunas
     • Section 702 and 703 requirements
   • Construction sites and agricultural premises
     • Reduced low voltage on sites (Section 704)
     • Agricultural and horticultural (Section 705)
   • Other special installations
     • Caravans, caravan parks and marinas
     • Solar PV systems (Section 712)
     • Electric vehicle charging (Section 722)

BS 7671 Wiring Regulations and Special Installations flashcards for City & Guilds Electrical Installation (Level 3)

19 of 55 cards from the BS 7671 Wiring Regulations and Special Installations deck — real questions with worked answers.

1. What is BS 7671 and what is its formal title?

   BS 7671 is the British Standard for electrical installations, formally titled the 'Requirements for Electrical Installations, IET Wiring Regulations'. It is a non-statutory document used to demonstrate compliance with the Electricity at Work Regulations 1989.

2. How is BS 7671 structured into Parts and Appendices?

   It comprises 7 Parts (Part 1 Scope, Part 2 Definitions, Part 3 Assessment, Part 4 Protection for safety, Part 5 Selection and erection, Part 6 Inspection and testing, Part 7 Special installations or locations) followed by a set of Appendices providing supporting information.

3. Which Part of BS 7671 contains the special installations and locations, and how are its numbers structured?

   Part 7. Each special location is given a section number in the 700 series (e.g. 701 baths/showers, 702 swimming pools), and its regulation numbers parallel the corresponding general chapters.

4. What does the numbering of a regulation such as 411.3.2.2 tell you about its location in BS 7671?

   The first digit (4) is the Part, the next digits give the Chapter (41), then the Section (411), then progressively the regulation group and individual regulation. So 411.3.2.2 is Part 4, Chapter 41, Section 411.

5. Is compliance with BS 7671 a legal requirement?

   BS 7671 is not statutory itself, but compliance is generally accepted as satisfying the legal duties of statutes such as the Electricity at Work Regulations 1989 and is referenced by Part P of the Building Regulations.

6. What is the scope of BS 7671 with respect to voltage?

   It applies to installations operating at voltages not exceeding $1000\text{ V}$ AC or $1500\text{ V}$ DC. Standard low voltage AC supplies fall within this scope.

7. Define 'low voltage' and 'extra-low voltage' as used in BS 7671.

   Low voltage (LV) is above extra-low voltage but not exceeding $1000\text{ V}$ AC or $1500\text{ V}$ DC between conductors. Extra-low voltage (ELV) does not exceed $50\text{ V}$ AC or $120\text{ V}$ ripple-free DC between conductors or to earth.

8. What is the fundamental principle of Chapter 13 regarding protection against electric shock?

   Persons and livestock must be protected against dangers arising from contact with live parts (basic protection) and from contact made hazardous by a fault (fault protection).

9. According to the fundamental principles, what must an installation provide protection against besides electric shock?

   Protection against thermal effects, overcurrent, fault current, overvoltage and undervoltage, and against the effects of supply interruption, plus protection of livestock and against fire/burns.

10. What is meant by 'basic protection' and 'fault protection' (the two facets of shock protection)?

    Basic protection prevents contact with live parts during normal operation (e.g. insulation, barriers, enclosures). Fault protection prevents danger from indirect contact under a single fault (e.g. automatic disconnection, earthing, bonding).

11. What general characteristics must be assessed under Part 3 of BS 7671?

    The purpose, supplies and structure of the installation; external influences; compatibility of equipment; maintainability; recurring safety services; and continuity of service requirements.

12. What does the assessment of 'external influences' in Part 3 cover, and how are they coded?

    It covers environmental, utilisation and building-construction conditions. Each is given a two-letter, one-number code: first letter = general category (A environment, B utilisation, C building), second letter = nature, number = class (e.g. $AD4$ = splashing water).

13. What does the external influence code $AD$ represent, and give examples of its classes.

    $AD$ represents the presence of water. Classes range from $AD1$ (negligible/dry) through $AD3$ (sprays), $AD4$ (splashes), $AD5$ (jets) to $AD8$ (submersion).

14. What are the principal earthing systems classified in BS 7671 and how are they designated?

    They are designated by letters: first = source earthing (T earthed, I isolated), second = installation earthing (T own electrode, N connected to source). Types are TN-S, TN-C-S (PME), TN-C, TT and IT.

15. Describe the TN-C-S (PME) earthing system.

    In TN-C-S the supply uses a combined neutral and earth (PEN) conductor up to the origin, then separate neutral and earth within the installation. It is the Protective Multiple Earthing arrangement and gives a low earth fault loop impedance.

16. Describe a TT earthing system and its key protective implication.

    In TT the supply is earthed at the source but the installation has its own earth electrode (no metallic earth from the supplier). Because earth electrode resistance is high, an RCD is normally required for fault protection.

17. What are the main types of supply that must be assessed under Part 3?

    Nature of current (AC/DC), purpose (normal, safety, standby), nominal voltage, frequency, prospective fault current at the origin, earth fault loop impedance $Z_e$, suitability/capacity, and the protective measures provided by the distributor.

18. Where in BS 7671 would you find current-carrying capacities of cables, and which appendix?

    In Appendix 4, which gives current-carrying capacity and voltage drop data for cables under various installation/reference methods, together with rating factors.

19. Which Appendix of BS 7671 explains the maximum demand and diversity guidance?

    Appendix 1 lists British Standards referenced; diversity/maximum demand allowances are given in Appendix (and the On-Site Guide), but the formal current-rating and correction-factor tables sit in Appendix 4.

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