| Full title | Requirements for Electrical Installations. IET Wiring Regulations. Eighteenth Edition |
| Publisher | The IET and BSI, jointly |
| Committee | JPEL/64, the UK national Wiring Regulations committee |
| Status | Current. BS 7671:2018+A2:2022+A3:2024 was withdrawn on 15 October 2026 |
| Based on | The IEC 60364 and CENELEC HD 60364 series, in technical intent rather than word for word |
| Legal status | Non-statutory, but referenced by UK law and guidance (see below) |
What BS 7671 is
BS 7671 sets the requirements for the design, erection and verification of electrical installations in the UK, covering installations up to 1000 V AC or 1500 V DC. It is the reference that electricians, designers and inspectors work to, and it is the basis of the electrical installation certificates and condition reports issued for completed work.
For data cabling it matters in three ways: it governs how data and power cables share routes, how equipment is earthed and bonded, and, since Amendment 4, how Power over Ethernet installations are designed.
Legal status
BS 7671 is not law in itself. The HSE’s guidance on the Electricity at Work Regulations 1989 (HSR25) describes it as non-statutory, and says that following it is likely to achieve compliance with the relevant parts of those Regulations. It is cited in law and statutory guidance elsewhere:
- England: Approved Document P, which supports Part P of the Building Regulations for electrical work in dwellings, says installations should be designed and installed in accordance with BS 7671. The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 define the required standard by reference to the 18th Edition.
- Scotland: the Building Standards Technical Handbook guidance on Standard 4.5 (electrical safety) refers to BS 7671.
- Not retrospective: an installation built to an earlier edition is not unsafe or non-compliant simply because a new edition has been published, and does not have to be upgraded for that reason. Periodic inspections are carried out against the current edition.
Amendment history
| Edition | Published | Main content |
|---|---|---|
| BS 7671:2018 | 2 July 2018 | 18th Edition. In effect from 1 January 2019 |
| A1:2020 | February 2020 | Section 722, electric vehicle charging |
| A2:2022 | 28 March 2022 | Part 8 and Chapter 82 (prosumer installations); pink became the only colour for functional earthing conductors, with cream dropped |
| A3:2024 | 31 July 2024 | Definitions of bidirectional and unidirectional protective devices; Regulation 530.3.201 |
| A4:2026 | 15 April 2026 | Section 545 (functional earthing for ICT), Section 716 (Power over Ethernet), Chapter 57 (stationary secondary batteries), revised Section 710 (medical locations) |
Structure
| Part | Title |
|---|---|
| 1 | Scope, object and fundamental principles |
| 2 | Terms and definitions |
| 3 | Assessment of general characteristics |
| 4 | Protection for safety |
| 5 | Selection and erection of equipment |
| 6 | Inspection and testing |
| 7 | Special installations or locations |
| 8 | Functional requirements |
Parts 1 to 7 broadly follow the structure of IEC 60364, so most section numbers match: Section 716 in BS 7671 corresponds to IEC 60364-7-716. Regulations numbered 2xx, such as 422.2.201, are UK additions. Part 8 was added by Amendment 2.
Regulations that affect data cabling
| Regulation | What it covers |
|---|---|
| Section 444 | Measures against electromagnetic disturbances, in Chapter 44. The basis for the functional earthing and bonding of ICT equipment |
| Regulation 528.1 | Band I circuits (including telecommunication, data and signalling) and Band II circuits (low voltage power) must not share a wiring system unless they are segregated or insulated for the highest voltage present |
| Regulation 528.2 | Buried power and telecommunication cables: keep at least 100 mm apart, or use a fire-retardant partition or mechanical protection at crossings |
| Regulation 521.10.202 | Wiring systems must be supported so they will not collapse prematurely in a fire. This applies to data cables as well as power |
| Regulation 422.2.1 | Cables in protected escape routes: flame propagation to BS EN 60332-3 (BS EN 60332-1-2 in a cable management system) and smoke to BS EN 61034-2, at least 60% light transmittance |
| Section 545 | Functional earthing and bonding for ICT equipment: conductor size, identification, continuity, the main functional earthing terminal and bonding ring conductors. New in Amendment 4 |
| Section 716 | Power over Ethernet. The source is either PSE to BS EN 62368-1 and BS EN 60950-22 meeting the interoperability requirements of ISO/IEC/IEEE 8802-3, or a Regulation 414.3 source not exceeding 60 V ripple-free DC in dry conditions and 15 V ripple-free DC elsewhere. Design current in any conductor must not exceed 750 mA. New in Amendment 4 |
Regulation 528.1 allows Band I and Band II cables in the same system when any of these applies:
- every cable is insulated for the highest voltage present;
- each core of a multicore cable is insulated for the highest voltage present;
- cables are insulated for their own system voltage and run in a separate compartment of trunking or ducting;
- cables run on a tray with a partition between them;
- a separate conduit, trunking or ducting system is used;
- in a multicore cable, the Band I and Band II cores are separated by an earthed metal screen.
BS 7671 deals with electrical safety. The separation distances for data performance, which depend on the cable type and containment, are set by BS EN 50174-2.
Voltage bands and ranges
| Term | Meaning |
|---|---|
| Extra-low voltage (ELV) | Not exceeding 50 V AC or 120 V ripple-free DC |
| Low voltage (LV) | Above ELV, up to 1000 V AC or 1500 V DC |
| Band I | Installations where protection against electric shock is provided by limiting the voltage, and installations where the voltage is limited for operational reasons, such as telecommunication, signalling, bell, control and alarm circuits. ELV normally falls in Band I |
| Band II | Supplies to household and most commercial and industrial installations. LV normally falls in Band II |
IET guidance publications
The IET publishes companion books updated to Amendment 4: the On-Site Guide (9th edition) and Guidance Notes 1 to 8. Guidance Note 1 covers selection and erection, 3 inspection and testing, 4 protection against fire and 8 earthing and bonding.
For what Amendment 4 means on site, read BS 7671 Amendment 4: what the new PoE and ICT earthing rules mean for data cabling.