The 17th Edition Wiring Regulations contains seven Parts and sixteen Appendices. Within this structure there are many thousands of regulations which although you are not expected to know by heart, you are expected to know where to them.

The Regulations themselves are contained with Sections and Chapters of the Parts of the 17th Edition.

Each part contains a chapter, each chapter contains sections, each section contains regulations. The Regulations themselves may contain multiple clauses. The Regulations is a well organised but complex document.

The 7 Parts Of The 17th Edition Wiring Regulations

Part 1     Scope, object and fundamental principles

Part 2     Definitions

Part 3     Assessment of general characteristics

Part 4     Protection for safety

Part 5     Selection and erection of equipment

Part 6     Inspection and testing

Part 7     Special installations or locations

The 16 Appendices Of The 17th Edition Wiring Regulations

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
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, DC and other systems
10. Protection of conductors in parallel against overcurrent
11. Effect of harmonic currents on … Moved to Appendix 4 sec 5.5 and 5.6
12. Voltage drop in consumers’ installations…Moved Appendix 4 sec 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

*Note that following the update BS7671:2008 Amendment 1 in 2011, two of the appendices, 11 and 12, were moved to Appendix 4. In effect this means there are in fact only fourteen appendices which contain information. Appendices 11 and 12 remain in the 17th Edition Wiring Regulations for information purposes.

Understanding the Structure of the Regulations

Although there are 7 parts and 16 Appendices, the 17th Edition Wiring Regulations can best be understood by considering it as organised into four chunks of information:

1. Part 1- Scope, object and fundamental principles
   This section outlines general requirements for installations
2. Part 2 – Definitions
   This section details the 290 definitions which are used in the Regulations
3. Part 3 to Part 7
   This is the body of the regulations, each part deals with a critical area of wiring regulations. Parts 3 to 6 describe general regulations in details and the longest part, Part 7 deals with special installations and locations.
4. Appendices
   The extensive appendices provide detail information related to the Wiring Regulations