BS 7671

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

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.

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
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.

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
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. 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
"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
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. 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
 * Amendment 3 highlights - non-combustible consumer units/enclosures