BS 7671, Requirements for Electrical Installations, better known as the IET Wiring Regulations, is the British Standard that sets the rules for designing, erecting, inspecting and testing low-voltage electrical installations in the UK. The current version is BS 7671:2018+A4:2026, the 18th Edition with Amendment 4, published by the IET and BSI on 15 April 2026. On 15 October 2026 the previous version (A2:2022 with the 2023 corrigendum and A3:2024) was withdrawn, so A4 is now the only current standard. Every EIC, Minor Works Certificate and EICR you sign either certifies compliance with it or reports an installation's condition against it.
- BS 7671 is a standard, not a law, but HSE, Approved Document P and the landlord regulations all treat compliance with it as the way to meet a legal duty.
- The 18th Edition (2018) has had four amendments: A1:2020, A2:2022, A3:2024 and A4:2026. The 2018 base text plus all four is what the orange book contains.
- A4 was published 15 April 2026 and became the sole current version on 15 October 2026. The Regs book is 640 pages and sells at £125 (Screwfix, 26 October 2026).
- A4's headline additions are Chapter 57 (stationary batteries), Section 545 (functional earthing for ICT), Section 716 (Power over Ethernet) and a rewritten Section 710 (medical locations), plus revised Appendix 6 model forms.
- BS 7671 is not retrospective. Older installations are judged on safety, and a non-dangerous departure from the current edition is a C3 on an EICR.
Where did BS 7671 come from?
The Wiring Regulations are older than the National Grid. The first edition appeared in 1882 as the Rules and Regulations for the Prevention of Fire Risks Arising from Electric Lighting, a four-page document of 21 rules issued by the Society of Telegraph Engineers and Electricians, the body that became the IEE in 1889 and, after merging with the Institution of Incorporated Engineers in 2006, the IET. The numbering you still hear on site, "the 16th", "the 17th", "the 18th", counts editions from that 1882 document.
The 16th Edition (1991) is the one that matters for the name. In 1992 it was adopted by the British Standards Institution and retitled Requirements for Electrical Installations, BS 7671:1992, which is why the standard carries a BSI number and an IET name at the same time. The 16th Edition also introduced certificates with recorded test results and schedules of inspection, the direct ancestors of the forms you fill in today. The 17th Edition (BS 7671:2008) was the first published jointly by the IET and BSI, brought in 30 mA RCD protection for general-use sockets, and its 2015 amendment required non-combustible consumer units. The 18th Edition (BS 7671:2018) was issued on 2 July 2018 and took effect on 1 January 2019.
Since the 15th Edition (1981) the UK text has followed the international IEC 60364 series and the CENELEC HD 60364 harmonisation documents, which is why regulation numbers such as 411.3.3 or 701.512.3 look the same in a German or Irish installation standard. The UK-specific additions are the regulations ending in .201, .202 and so on.
What does the book actually contain?
BS 7671 is organised into eight parts followed by appendices. Knowing the layout is the quickest way to find a regulation under pressure, because the first digit of any regulation number is the part it lives in.
| Part | Covers | Regulations you use most on certificates |
|---|---|---|
| 1 Scope, object and fundamental principles | What the standard applies to (110.1.1), departures (120.3), design responsibility (132), alterations and additions (132.16) | 120.3 departures box on the EIC; 132.16 for the existing installation |
| 2 Definitions | Every defined term, including PNB and the new battery and TSE definitions from A4 | Earthing arrangement names, "skilled person", "competent person" |
| 3 Assessment of general characteristics | Supply characteristics, earthing arrangements (312.2), maximum demand, external influences | Section B of the EIC: TN-S, TN-C-S (PME), TN-C-S (PNB), TT |
| 4 Protection for safety | Shock (Chapter 41, including 411.3.3 RCDs and Tables 41.2 to 41.5 maximum Zs), thermal effects (Chapter 42, including 421.1.7 AFDDs and 421.1.201 consumer units), overcurrent (43), voltage disturbances and SPDs (44) | Max Zs column, RCD and AFDD entries, SPD item 4.19 on the EICR |
| 5 Selection and erection | Identification (Table 51), wiring systems (52), protective devices and isolation (53, including 530.3.201 bidirectional devices), earthing (54, including Section 545), other equipment (55), safety services (56), stationary batteries (57, new in A4) | Earthing and bonding conductor sizes, cable reference methods |
| 6 Inspection and testing | Initial verification (Chapter 64), periodic inspection (Chapter 65), test methods (643), certification (644), reporting (653) | The whole certificate: 643 test sequence, 644.4.201 one Minor Works per circuit, 653.1 EICR |
| 7 Special installations or locations | 701 bathrooms, 702 pools and hot tubs, 704 construction sites, 705 agricultural, 708/709 caravan parks and marinas, 710 medical, 712 solar PV, 714 outdoor lighting, 716 PoE (new), 722 EV charging, 730 onshore units | The "special location" tick in Part P and the extra tests each section calls for |
| 8 Functional requirements | Chapter 81 energy efficiency (informative, moved here from Appendix 17 by A4), Chapter 82 prosumer installations | Rarely on a domestic cert, but Chapter 82 applies where there is local generation or storage |
The appendices carry the material you consult daily: Appendix 3 (time/current characteristics and the 0.8 rule for measured Zs), Appendix 4 (cable current-carrying capacities, with A4 adding installation methods 72 and 73 and reference method D2 for buried cables), Appendix 6 (the model certificate forms) and Appendix 13 (escape routes and fire protection, rewritten in A4). Appendix 1 became normative in A4 and lists every other standard the book references.
Is BS 7671 a legal requirement?
No, and yes. BS 7671 is a British Standard published by two non-governmental bodies, so breaching it is not itself an offence. Its legal weight comes from the statutory instruments that lean on it.
| Instrument | Who it binds | How it uses BS 7671 |
|---|---|---|
| Electricity at Work Regulations 1989 | Every employer, employee and self-employed person, so every working electrician | Regulation 4(1) requires systems to be constructed so as to prevent danger so far as reasonably practicable, 4(2) requires them to be maintained. HSE's guidance HSR25 (third edition, 2015, paragraph 9) says BS 7671 "is a code of practice which is widely recognised and accepted in the UK" and that following it is likely to achieve compliance with the relevant aspects of the Regulations |
| Part P of the Building Regulations 2010 (England and Wales) | Anyone carrying out electrical work in dwellings | Requirement P1 asks for "reasonable provision" to protect people from fire or injury. Approved Document P (2013 edition) says installations "should be designed and installed in accordance with BS 7671". The 2013 document still names BS 7671:2008+A1:2011, but its own "how to use" section allows a newer version of a listed standard where it still covers the requirement, and the competent person schemes assess against the current edition |
| Electrical Safety Standards in the Private Rented Sector and Social Rented Sector (England) Regulations | Private landlords from 2020, social landlords from 1 November 2025 | Define "electrical safety standards" as the 18th Edition of the Wiring Regulations, require a 5-yearly EICR, remedials within 28 days and a civil penalty of up to £40,000 |
| Building (Scotland) Regulations 2004 | Electrical work in Scottish buildings | Technical Handbook Standard 4.5 cites BS 7671 as the means of meeting the electrical safety standard; certification is through SELECT and NICEIC approved certifiers |
| Electricity Safety, Quality and Continuity Regulations 2002 | Distributors and generators | Regulation 8(4) and ENA Engineering Recommendation G12 govern PME, and the regulations require certain generator-connected installations to conform to BS 7671 |
The practical consequence is that if your work complies with BS 7671 you have a ready-made defence under the Electricity at Work Regulations, and if it does not, you need to show why your departure is at least as safe. That is what the departures box on the EIC (Regulation 120.3) is for. See the guide on Part P notification for how the building regulations side works in practice, and the England landlord EICR regulations for the rented-sector duties.
How have the amendments changed the 18th Edition?
Each amendment is published as a complete consolidated book, so "A4" means the 2018 text plus everything from A1 to A4. The dates matter when you are reading an old certificate or deciding what a job was designed to.
| Version | Published | Status | What it brought |
|---|---|---|---|
| BS 7671:2018 (18th Edition, blue cover) | 2 July 2018, effective 1 January 2019 | Superseded | AFDDs recommended, SPD requirements in Section 443, Section 722 EV charging rewritten, energy efficiency in Appendix 17 |
| A1:2020 | 1 February 2020 | Superseded | Short amendment revising Section 722 (EV charging), including the PME restrictions and open-PEN device options |
| A2:2022 (brown cover) | 28 March 2022, six-month transition to the end of September 2022 | Withdrawn 15 October 2026 | AFDDs required in HMOs, student accommodation, care homes and higher-risk residential buildings (421.1.7); Type AC RCD restrictions (531.3.3); Chapter 82 prosumer installations; SPD opt-out moved to the owner of the installation (443.4.1); new certificate forms with separate circuit details and test results schedules. A corrigendum followed in May 2023 |
| A3:2024 | 31 July 2024, effective immediately | Withdrawn 15 October 2026 | New Regulation 530.3.201 on unidirectional and bidirectional protective devices, with two new definitions, for boards feeding PV and battery storage |
| A4:2026 (orange cover) | 15 April 2026, six-month transition | Current, sole version from 15 October 2026 | Chapter 57 batteries, Section 545 ICT functional earthing, Section 716 PoE, Section 710 rewritten, PNB earthing, pink functional earth conductors, revised Appendix 6 forms, Appendix 17 removed in favour of Chapter 81 |
One trap: the A4 book is dated 2026 but the amendment also carries forward A3's bidirectional-device rule, so an "A3" board requirement does not disappear just because A3 was withdrawn. The content lives on in the consolidated text.
What did Amendment 4 change that affects certificates?
The IET and BSI published A4 on 15 April 2026 and it could be used immediately. Work designed to A2/A3 before 15 October 2026 can still be erected and certified to that version, subject to the contract, but NICEIC's guidance is to discuss it with the client and to issue A4 certificates for anything started on or after 15 October. These are the changes you will meet on the forms and on site, taken from the SELECT and NICEIC summaries of the amendment.
Scope and definitions. Regulation 110.1.1 adds stationary secondary batteries and Power over Ethernet to the scope. Part 2 gains definitions of battery, primary and secondary cell, transfer switching equipment, balanced cable and protective neutral bonding (PNB). PNB is a TN-C-S variant with a single-source earth connection to the neutral near the consumer's terminals (Regulation 312.2.1.1 and new Figure 3.9B), and it now appears as a selectable earthing arrangement on the certificates, so Section B of an EIC offers TN-C-S (PME) and TN-C-S (PNB) separately. The full set is covered in the earthing arrangements guide.
Protection for safety. Regulation 421.1.7(a) now says "high rise residential buildings" instead of "higher risk residential buildings" to avoid confusion with Building Safety Act terminology. NICEIC describes these as buildings over 18 m or more than six storeys. Nothing changed about where AFDDs are required, and new Regulation 722.421.1.7.201 confirms AFDDs are not required for circuits supplying EV charging equipment to BS EN 61851 with BS EN IEC 62196-2 connectors. Regulations 422.2.201 and 422.2.202 restrict what may be run through fire-fighting shafts and protected stairways, and Appendix 13 was rewritten to match. The AFDD detail is in the AFDD explainer.
Selection and erection. Table 51 makes pink the identifier for functional earthing and functional bonding conductors, replacing cream, with green-and-yellow not permitted for that purpose. Regulation 526.2 requires the conductor class (new Table 52.4) to be considered when choosing a connection method, with a note that fine-wire conductors may need crimps. Regulation 536.4.202 was redrafted so that diversity cannot be used as a means of load curtailment in an assembly. Regulation 551.7.1 adds indents (c) and (d) on bidirectional energy flow and on not connecting a source to the load side of an RCD, and 551.7.2.2 sets out how to rate a consumer unit that has a generator running in parallel: InA at least In plus Ig, so a 100 A supply with a 16 A inverter wants a 116 A-rated assembly.
Chapter 57 and the special locations. Chapter 57 brings more than 18 new regulations for stationary secondary batteries, covering selection, power conversion equipment, earthing, shock protection, d.c.-side fault protection, isolation and notices. Regulation 570.6.7.203 requires batteries in dwellings to be sited with regard to the manufacturer's instructions and PAS 63100, and a Type B RCD is required unless the power conversion equipment provides simple separation, separation is provided by transformer windings, or the manufacturer states a Type B is not needed. Section 716 covers Power over Ethernet, with a 750 mA per-conductor design limit and PSE sources to BS EN 62368-1. Section 710 was rewritten for medical locations and gains Annex B710, a model schedule for recording supplementary bonding conductor resistance. Section 702 now includes outdoor hot tubs and religious pools explicitly, with hot tubs to conform to BS EN 60335-2-60. Section 714 confirms street furniture and traffic signals are in scope and requires RCD additional protection for publicly accessible lighting under 714.411.3.4. Neither Section 712 solar PV nor Sections 443 and 534 on surge protection changed in A4; see the Section 712 guide and the SPD guide.
Inspection, testing and the forms. Regulation 653.1 requires an EICR based on the Appendix 6 model, with the notes for the person producing the report rewritten, and 653.2 requires the recipient guidance, also redrafted, with a note permitting photographs and thermal images to be appended. The A4 model EICR separates C1 and C2 observations, which make the report unsatisfactory, from C3 and FI items, which do not, and the FI wording no longer says "without delay". The Minor Works form relabels the end-to-end ring readings as r1, rn and r2 instead of L/L, N/N and cpc/cpc. For bidirectional devices you record the British Standard of the device only; the comment box is there if you want to note the direction. Forms carry an 18.4 reference to show they are the A4 versions. The column-by-column walk-through is in how to do an EICR step by step and what is an EICR.
How do I cite BS 7671 on a certificate?
The declaration on the IET model forms says the work has been designed, constructed, inspected and tested in accordance with BS 7671:2018, amended to a date you write in. That date is the amendment you designed and verified against, not the date of the job. Three rules keep you right.
First, for any work designed on or after 15 October 2026, write 2026 (A4). An "A2:2022" declaration on a job that started after the withdrawal date cites a superseded document, and a scheme assessor will pick it up.
Second, for a job designed before 15 October 2026 and still in progress, you may complete and certify it to A2/A3, but agree that with the client and record it. If anything in the design is cheaper to bring to A4 than to argue about, bring it to A4.
Third, on an EICR the edition you cite is the one you inspected against, which should always be the current edition. The installation itself is not expected to comply with A4; you are using A4 as the yardstick for safety, and anything that fails that yardstick without being dangerous is a C3. The coding logic is in the observation codes guide and the limits in the unsatisfactory EICR guide.
What are the supporting IET publications?
The Regs book gives requirements, not methods. The IET publishes the method books alongside it and they were all reissued for A4.
| Publication | A4 edition | Use it for |
|---|---|---|
| BS 7671:2018+A4:2026 | Published 15 April 2026, 640 pages, £125 at Screwfix on 26 October 2026 | The requirements themselves; the only document you can cite on a certificate |
| On-Site Guide | 9th edition, 2026 | Domestic and small commercial design tables, maximum Zs figures already corrected for conductor temperature, the IR and continuity quick references |
| Guidance Note 3, Inspection and Testing | 10th edition, published 15 April 2026 | Test methods, the recommended intervals in Table 3.2, maximum measured Zs, the inspection schedule items; the book NICEIC and NAPIT expect your test procedures to follow |
| Guidance Notes 1, 2, 4 to 8 | Updated for A4 through 2026 | Selection and erection (1), isolation and switching (2), protection against fire (4), shock (5), overcurrent (6), special locations (7), earthing and bonding (8) |
| Electrical Safety First Best Practice Guide 4 | Issue 7.4, August 2026 | Classification codes for EICR observations; the industry reference for C1, C2, C3 and FI decisions |
The Electrotechnical Assessment Specification (EAS), published by the IET with a June 2026 edition, is the other document scheme assessors work from. It sets the qualification and Qualified Supervisor requirements for NICEIC, NAPIT and the other schemes, including evidence of a current BS 7671 qualification within two years of an edition change. That is why the Level 3 BS 7671 award (City & Guilds 2382 and the EAL equivalent) was reissued for A4 in 2026. The QS side is explained in the Qualified Supervisor guide.
Common mistakes with BS 7671
Citing the wrong edition. After 15 October 2026 "BS 7671:2018+A2:2022" is a superseded reference on new work.
Treating a departure from the current edition as a C2. The standard is not retrospective. A non-dangerous departure is a C3, and C3s alone leave an EICR satisfactory.
Quoting regulation numbers from memory. Numbers shift between amendments: the Type B RCD requirement for PV moved from 712.411.3.2.1.2 to 712.531.3.5.12 at A2, the SPD risk-assessment regulation 443.5 was deleted, and A4 moved energy efficiency from Appendix 17 to Chapter 81. Check the current book before writing a number on a form.
Treating 653.2 as the interval regulation. In A4, 653.2 is the requirement to give the recipient guidance with the EICR. The interval is a judgement made under Chapter 65 using GN3 Table 3.2, with the next inspection date recorded in Section F of the report.
Missing the carried-forward rules. A3's bidirectional-device regulation 530.3.201 and A2's Type AC RCD restriction still apply under A4. The withdrawn documents are withdrawn because their content is now inside A4, not because the rules went away.
Confusing Part P with BS 7671. Part P is the building regulation requirement and the notification duty. BS 7671 is the technical standard that satisfies it.
How Certio helps
Certio produces the EICR, EIC, Minor Works certificate and PAT records on the BS 7671 model forms and turns them into branded PDFs. Photograph the consumer unit and the circuit schedule drafts itself; point the phone camera at a Megger MFT-X1 and the reading goes straight into the schedule of test results, or dictate it while your hands stay on the probes. Suggested observation wording with the regulation reference is there for you to check and confirm. The judgement stays yours; the typing goes. Starter is £4.99 a month, charged when you sign up.