BS 7671

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British Standard BS 7671 "Requirements for Electrical Installations. IET Wiring Regulations", informally called in the UK electrical community "The Regs", is the national standard in the United Kingdom for electrical installation and the safety of electrical wiring systems[1]

SCOPE of BS 7671

The regulations in BS7671 applies to the design, selection, erection and verification of electrical installations within;

  1. residential properties
  2. commercial properties
  3. public premises
  4. industrial premises
  5. prefabricated building
  6. low voltage generating sets
  7. highway equipment and street furniture
  8. locations containing a bath or shower
  9. rooms or cabins that contain a sauna
  10. swimming pools and other basins
  11. construction and demolition sites
  12. agricultural and horticultural premises
  13. caravan/camping parks and similar locations
  14. marinas and similar locations
  15. medical locations
  16. exhibitions, shows and stands
  17. Solar photovoltaic (PV) power supply systems (Domestic and commercial)
  18. outdoor lighting installations
  19. extra-low voltage lighting
  20. mobile and transportable units
  21. caravans and motor caravans
  22. temporary installations for structures, amusement devices/booths at fairgrounds, amusement parks, circuses and professional stage and broadcast applications
  23. operating and maintenance gangways
  24. floor and ceiling heating systems
  25. onshore units of electrical shore connections for inland navigation vessels.

Exclusions from the scope of BS 7671 are the following.

  1. systems for the distribution of electricity to the public other than prosumer's installations covered by Chapter 82
  2. Railway traction equipment, rolling stock and signalling equipment
  3. Equipment of motor vehicles, except those to which the requirements of the Regulations concerning caravans or other types of mobile unit are applicable.
  4. Equipment on board ships covered by BS 8450, BS EN 60092-507, BS EN ISO 13297 or BS EN ISO 10133
  5. Equipment of mobile or fixed offshore installations.
  6. Equipment within and aircraft.
  7. Those aspects of mines covered by Statutory Regulations
  8. Radio interference suppression equipment, except so far as it affects safety of the electrical installation.
  9. Lightning protection systems for buildings and structures covered by BS EN 62305.
  10. Those aspects of Lift Installations covered by relevant parts of BS 5655 and BS EN 81 and those aspects of escalator or moving walkway installations covered by relevant parts of BS 5656 and BS EN 115.
  11. Electrical equipment of machines covered by BS EN 60204.
  12. Electric fences covered by BS EN 60335-2-76
  13. The DC side of cathodic protection systems complying with the relevant part(s) of BS EN 12696, BS EN 12954, BS EN ISO 13174, BS EN 13636 and BS EN 14505.

BS 7671 only covers electrical systems that the IET defines as those covered by the following.

  • Circuits supplied at a nominal voltage up to, but not exceeding 1000V AC or 1500V DC.
  • For AC the preferred frequencies of the supply are 50Hz, 60Hz and 400Hz. The use of other frequencies for special purposes in not excluded.

Part 2 - Definitions the voltages covered by BS7671 are defined thus.

Voltage, nominal (U0). The voltage by which an installation (or part of an installation) is designated and the following ranges of nominal voltage (rms values for AC) are defined

  • Extra-low. Not exceeding 50V AC or 120V ripple free DC, whether between conductors or Earth
  • Low. Exceeding extra-low voltage but not exceeding 1000V AC or 1500V DC between conductors or 600V AC or 900V DC between conductors and Earth.
  • High. Voltages that normally exceed those of Low voltage.

It did not become a recognized British Standard until after the publication of the 16th edition in 1992. The standard takes account of the technical substance of agreements reached in CENELEC.[2]

The current version is BS 7671:2018+A2:2022 (the 18th Edition) issued in 2022, and came into effect from 28 March 2022 (the previous version BS 7671:2018+A1:2020 being withdrawn on 27 September 2022). BS 7671 is also used as a national standard by Mauritius, St Lucia, Saint Vincent and the Grenadines, Sierra Leone, Singapore, Sri Lanka, Trinidad and Tobago, Uganda, Cyprus, and several other countries, which base their wiring regulations on BS 7671.

Compilation and publication[edit]

The standard is maintained by the Joint IET/BSI Technical Committee JPEL/64, the UK National Committee for Wiring Regulations, and published jointly by the IET (formerly IEE) and BSI. Although the IET and BSI are non-governmental organisations and the Wiring Regulations are non-statutory, they are referenced in several UK statutory instruments, and in most cases, for practical purposes, have legal force as the appropriate method of electric wiring.[3]

The BSI (British Standards Institute) publishes numerous titles concerning acceptable standards of design/safety/quality across different fields.

History of BS 7671 and predecessor standards[edit]

The first edition was published in 1882 as the "Rules and Regulations for the Prevention of Fire Risks arising from Electric Lighting." The title became "General Rules recommended for Wiring for the Supply of Electrical Energy" with the third edition in 1897, "Wiring Rules" with the fifth edition of 1907, and settled at "Regulations for the Electrical Equipment of Buildings" with the eighth edition in 1924.

Since the 15th edition (1981), these regulations have closely followed the corresponding international standard IEC 60364. In 1992, the IEE Wiring Regulations became British Standard BS 7671 so that the legal enforcement of their requirements was easier both with regard to the Electricity at Work regulations and from an international point of view.[4] They are now treated similar to other British Standards. BS 7671 has converged towards (and is largely based on) the European Committee for Electrotechnical Standardization (CENELEC) harmonisation documents, and therefore is technically very similar to the current wiring regulations of other European countries.

1st Edition[edit]

"Rules and Regulations for the Prevention of Fire Risks arising from Electric Lighting." - Two core cable, line and neutral, no earth. The protection was a re-wirable fuse.

17th Edition[edit]

A bookstore selling the 17th Edition in 2008

The 17th edition, released in January 2008 and amended in 2011 ("Amendment 1"), 2013 ("Amendment 2") and January 2015 ("Amendment 3") became effective for all installations designed after 1 July 2008.[5] One of the more significant changes is (chapter 41) that 30 mA RCDs will be required for socket outlets that are for use by ordinary persons and are intended for general use. This improves the level of protection against electrical shock in the UK to a level comparable to that in other EU countries, where the residual current breaker is usually found in the main- or group central. The 17th edition and its amendments incorporated new sections relating to microgeneration and solar photovoltaic systems, non-combustible consumer units, RCDs, and breakers (including high resilience breaker layout).

  • As originally published highlights - RCDs required for most outlets
  • Amendment 1 highlights - high resilience consumer units
  • Amendment 2 highlights - electric vehicle charging added, earlier change incorporated for medical locations[6]
  • Amendment 3 highlights - non-combustible consumer units/enclosures[7]

18th Edition[edit]


Date Edition / change Information
1882 1st Edition Titled ‘Rules and Regulations for the prevention of Fire Risks Arising from Electric Lighting’, and known as the "Wiring Rules"
1888 2nd Edition Titled 'Wiring Rules & Regulations in Buildings
1897 3rd Edition Titled ‘General Rules recommended for Wiring for the Supply of Electrical Energy’
1903 4th Edition issued as IEE Wiring Regulations, called ‘Wiring Rules’
1907 5th Edition Issued as IEE Wiring Regulations
1911 6th Edition Issued as IEE Wiring Regulations
1916 7th Edition Issued as IEE Wiring Regulations
1924 8th Edition Issued as IEE Wiring Regulations ‘Regulations for the Electrical Equipment of Buildings’
1927 9th Edition Issued as IEE Wiring Regulations
1934 10th Edition Issued as IEE Wiring Regulations 3 phase colours red, white and green, neutral or earth black.
1939 11th Edition Issued as IEE Wiring Regulations. Revised in 1943, reprint with minor amendments in 1945, supplement in 1946, further revised in 1948 last edition to allow sockets in a bathroom. 3 phase colours red, white and blue, Black for neutral or earth.
1950 12th Edition Issued as IEE Wiring Regulations. Supplement issued 1954 First mention of PVC insulated cables.

3 phase colours red white and blue, Black for neutral or earth in fixed wiring. Green earth in flex.

1955 13th Edition Issued as IEE Wiring Regulations. Reprinted in 1958, 1961, 1962, 1964
1966 14th Edition Issued as IEE Wiring Regulations. (adds earthing on lighting circuits) Reprinted in 1968, 1969, 1969 again (metric units[verification needed]), 1970 (in metric units), 1972, 1973, 1974, 1976
1981 15th Edition Issued as IEE Wiring Regulations. (Possibly reprinted 1983, 1984, 1986 amendment to remove voltage operated earth leakage circuit breakers), 1987, 1988?[verification needed])
1991 16th Edition Issued as IEE Wiring Regulations. Reprinted with amendments 1992, 1994, 1997, 2000, 2001, 2004
1992 BSI adopts as a standard Wiring Regulations adopted by the British Standards Institute as BS 7671
1992 Legislation Electricity at Work Regulations come fully into effect in Northern Ireland
2004 Incorporated into building regulations Part P of the Building Regulations ("Requirements for Electrical Installations") comes into force, covering legal requirements for electrical installations in England and Wales. The guidance in the Approved Documents refers to BS 7671 as being one way to achieve compliance. The version in force when the law came into effect was the 16th edition, BS 7671:2001, as amended in 2002 and 2004 Amendment 2 (change of phase colours) .
2008 17th Edition Amended 2015 ("Amendment no. 3") metal consumer units.
2018 18th Edition Introduced energy efficiency performance levels and the use of surge protection devices and arc fault detection devices.[8]

Amended February 2020 ("Amendment no. 1") Changes to rules on car charging.

Amended March 2022 ("Amendment no. 2") Current standard as of March 2022

See also[edit]


  1. ^ BS7671 chapter 11 - scope
  2. ^ BS7671: Preface
  3. ^ "Regulatory Requirements" (PDF). p. 3.
  4. ^ Electrician's guide to the 17th edition of the IEE wiring regulations. 3rd edition pub 2012 John Whitfield
  5. ^ Geoff Cronshaw: The 17th edition: a brief overview Archived 3 September 2014 at the Wayback Machine. IEE Wiring Matters, Summer 2007.
  6. ^ "IET launches Amendment 3 to BS 7671:2008". Voltimum UK. Retrieved 1 March 2018.
  7. ^ "IET launches Amendment to Wiring Regulations". The IET. Retrieved 1 March 2018.
  8. ^ Whitton, Nicole (2016). "BS 7671: the 18th Edition report". IET Electrical. Retrieved 8 February 2018.

External links[edit]