Overview
British Standard BS 7671 is the national standard in the United Kingdom for low voltage electrical installations.
The IET (Institution of Engineering and Technology) has published wiring regulations in the United Kingdom since 1882. Since their 15th edition (1981), these regulations have closely followed the corresponding international standard IEC 60364.
Today, they are largely based on the European Committee for Electrotechnical Standardization (CENELEC) harmonization documents, and therefore are technically very similar to the current wiring regulations of other European countries.
It is also used as a national standard by Mauritius, St Lucia, Saint Vincent and the Grenadines, Sierra Leone, Sri Lanka, Trinidad and Tobago, and Uganda, and several other countries who base their wiring regulations on BS 7671.
In 1992, the IET Wiring Regulations became British Standard BS 7671 and they are now treated similar to other British Standards. They are maintained by the Joint IET/BSI Technical Committee JPEL/64, the UK National Committee for Wiring Regulations. Although the IET and BSI are non-governmental organizations and the Wiring Regulations are non-statutory, they are referenced in several UK statutory instruments.
The BSI publish numerous titles concerning acceptable standards of design/safety/quality etc. in various fields. BS 7671 concerns the safety of electrical wiring in buildings (dwellings, commercial, industrial or otherwise) and is generally known as the “Regs” (wiring regulations).
18th Edition
The 18th Edition, BS 7671:2018, is the current edition of the Wiring Regulations, and it has been amended since it was published. Each new edition and each amendment applies to installations designed after the date it takes effect, so an installation is judged against the edition it was designed to, not the one in print today. That is one of the reasons an older installation can be perfectly serviceable and still show departures on a condition report.
One of the more significant changes carried by the current edition is that 30mA RCDs are 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.
The current edition also carries sections relating to microgeneration and solar photovoltaic systems, and to electric vehicle charging installations, which is why an EV charger or a solar array is not a job for a general handyman.
Cable core colours
Fixed wiring in the UK uses the harmonised cable core colours. On a single phase circuit that is brown for the line (live) conductor, blue for the neutral conductor, and green-and-yellow for the protective (earth) conductor.
If you open a fitting in your home and find red and black conductors, the wiring predates the changeover and is worth having looked at. Please note the presence of old colours is not in itself a fault, but it does tell you the age of the installation.
The I.E.E. (The Institution of Electrical Engineers)
A bit of history, because customers often ask why the regulations carry two different sets of initials.
The Institution of Electrical Engineers (I.E.E.) was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. The I.E.E. was founded in 1871 as the Society of Telegraph Engineers, changed its name in 1880 to the Society of Telegraph Engineers and Electricians and changed it again to the Institution of Electrical Engineers in 1889. It was Incorporated by a Royal Charter in 1921.
In 2006, the I.E.E. merged with the Institution of Incorporated Engineers (I.I.E.) to form the Institution of Engineering and Technology (I.E.T.). Before the merger, the I.E.E. was the largest professional engineering society in Europe, with a worldwide membership of around 120,000.
So anything printed before 2006 says IEE, and everything current says IET. It is the same body.
IEC (International Electrotechnical Commission)
The IEC is the international organisation for the preparation of safety standards and other standards in the area of electrical engineering. International orientation on the focus of its activities is a stated objective of electrotechnical standardisation.
High, Low and Extra Low Voltage
The International Electrotechnical Commission and its national counterparts (IET, IEEE, VDE, etc.) define high voltage circuits as those with more than 1000 V for alternating current and at least 1500 V for direct current, and distinguish it from low voltage (50 to 1000 V AC or 120 to 1500 V DC) and extra-low voltage (below 50 V AC or below 120 V DC) circuits. This is in the context of building wiring and the safety of electrical apparatus.
Low Voltage
This is an electrical engineering term that broadly identifies safety considerations of an electricity supply system based on the voltage used. While different definitions exist for the exact voltage range covered by “low voltage”, most usually 50 to 1000 V AC, the most commonly used ones include “mains voltage”, 230 V AC.
“Low voltage” is characterised by carrying a substantial risk of electric shock, but only a minor risk of electric arcs through air. “Low voltage” is distinguished from:
Extra low voltage, which carries a much reduced risk of electric shock
High voltage, where electrical arcing is a substantial additional risk
Why use us?
ProElec Electrical Services Ltd is an NICEIC Approved Contractor, and our electricians work to the 18th Edition IET Wiring Regulations (BS 7671).
All electrical work meets the requirements of Part P electrical safety.
All our electricians and staff are uniformed and carry company identification.
More information
For more information please contact us or telephone us directly on 01925 222197