When was BS 7671 Amendment 4 published?

BS 7671:2018+A4:2026 was issued on 15 April 2026 and could be used immediately. The previous version (A2:2022 + Corrigendum + A3:2024) was withdrawn on 15 October 2026.

Is BS 7671 A4:2026 a new edition?

No. It is the fourth amendment to the 18th Edition, BS 7671:2018, and comes as a full reprint with an orange cover. A copy marked +A2:2022 does not include Chapter 57, Section 545 or Section 716.

Did A4 make AFDDs compulsory?

No. AFDDs became a requirement on socket circuits up to 32 A in high rise residential buildings, HMOs, purpose-built student accommodation and care homes at A2:2022. A4 reworded item (a) to "high rise residential buildings" and added a regulation saying AFDDs are not required for proper EV charging equipment.

Do I need to upgrade existing installations to A4?

No. BS 7671 is not retrospective. The book says installations built to earlier editions may not comply in every respect, which does not necessarily mean they are unsafe or need upgrading. Additions and alterations are designed to A4.

Which exam covers A4?

The City & Guilds 2382-26 covers BS 7671:2018+A4:2026. Only your own copy of the A4 book is allowed in the exam. Elec-Mate has a free 18th Edition mock exam written against A4:2026.

A4:2026

BS 7671 Amendment 4: every change explained

BS 7671:2018+A4:2026 was issued on 15 April 2026, and the A2 and A3 version was withdrawn on 15 October 2026. This guide lists what Amendment 4 changed, part by part, from the book's own change summary, and flags the rules that are often credited to A4 but came earlier.

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9 min readUpdated 2026-10-28Andrew Moore, Founder of Elec-Mate

Written and reviewed by Andrew Moore, founder of Elec-Mate, against BS 7671:2018+A4:2026, IET Guidance Note 3 and the IET On-Site Guide.

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The short answer

What changed in BS 7671 Amendment 4?

A4:2026 added TN-C-S (PNB) earthing (Regulation 312.2.1.1), Table 52.1 for cables in walls, a new Chapter 57 for stationary batteries, new Section 545 (ICT functional earthing), new Section 716 (Power over Ethernet), a new Chapter 81 on energy efficiency, a major revision of Section 710 (medical locations) and revised model forms, on which an FI observation no longer has to make an EICR unsatisfactory.

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Key takeaways

01Issued 15 April 2026; the A2:2022 + A3:2024 version was withdrawn on 15 October 2026, so new work is designed to BS 7671:2018+A4:2026.
02New in A4: Chapter 57 (stationary secondary batteries), Section 545 (functional earthing for ICT), Section 716 (Power over Ethernet) and Chapter 81 (energy efficiency, replacing Appendix 17).
03Earthing: Regulation 312.2.1.1 now includes TN-C-S (PNB) alongside PME, and the model forms list them separately.
04Cables: requirements for cables in walls and partitions are now in Table 52.1, and Appendix 4 has new reference methods for buried cables.
05Reports: an FI observation no longer has to be marked unsatisfactory, and an EICR must include guidance for the recipient (Regulation 653.2).
06Not A4: the AFDD requirement, the single RCD test, the 250 V insulation test after reconnection and the SPD/AFDD form fields came in A2:2022; RCD protection for domestic lighting came in 2018.

01 · A4:2026

Key dates

BS 7671:2018 issued July 2018 (in force January 2019).
Amendment 1:2020 (Section 722, EV charging), February 2020.
Amendment 2:2022, March 2022.
Amendment 3:2024 (unidirectional and bidirectional protective devices), July 2024.
Amendment 4:2026 issued 15 April 2026 (orange cover). The A2:2022 + Corrigendum + A3:2024 version was withdrawn on 15 October 2026.

Existing installations

The book is clear that installations built to an earlier edition may not comply with A4 in every respect, and that this does not necessarily mean they are unsafe or need upgrading.

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Every key change in the 2026 amendment on one page. AFDDs, TN-C-S protection, new schedule columns, model forms. Pinned on your van dash.

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02 · A4:2026

Parts 2, 3 and 4: definitions, earthing and protection

Part 2: terms and definitions expanded and modified, including protective neutral bonding (PNB).
Regulation 312.2.1.1: a PNB figure and requirements added. TN-C-S (PNB) is earthed at a single point near the consumer and sits alongside TN-C-S (PME). See our TN-C-S (PNB) vs PME guide.
Regulation 421.1.7(a): reworded to "high rise residential buildings". The AFDD requirement itself dates from A2:2022.
Regulation 422.2 (protected escape routes): cables meeting 422.2.1 can be installed in a protected corridor; cables in a fire-resisting enclosure are deemed outside the escape route; 422.2.1 now lists the permitted cables.
Regulations 434.2.1 and 434.3(a): the term "inherently short-circuit and earth fault proof" introduced, with related changes.
Section 444: Annex B443 deleted.

03 · A4:2026

Part 5: selection and erection

Table 51: new identification for combined protective and functional earthing conductors, combined protective and functional bonding conductors and functional bonding conductors. Neither FE nor green-and-yellow should be used for a functional bonding conductor.
Regulation 521.10.202 (supports against premature collapse): a note added explaining its intent.
Section 522: the requirements for cables in a wall or partition are now in Table 52.1.
Regulation 536.4.202: redrafted to cover coordination between an LV switchgear assembly and its overload protective device, including load curtailment as one of the conditions.
Regulation 537.4.2: firefighter's switches now required where the fire engineer specifies them; 537.4.2.1 deleted.
New Section 545: functional earthing and functional equipotential bonding for ICT equipment (minimum sizes, identification, continuity, main functional earthing terminal, bonding ring conductors).
Section 551: 551.7.1 gains indents on bidirectional energy flow and on connecting a source to the load side of an RCD; 551.7.2 split in two, with stationary batteries treated as a generating set.
Chapter 56: 560.5.3 amended and the 560.6 rules on sources for safety services modified.
New Chapter 57: stationary secondary batteries used for storage and supply, excluding batteries inside products such as UPSs and emergency lighting.

04 · A4:2026

Part 6, Part 7 and Part 8

Regulation 653.1: the Appendix 6 notes for the person producing the report must be taken into account.
Regulation 653.2: an EICR must include guidance for the recipient, and photographs or thermographic images can be appended.
Section 710 (medical locations): major revision, including independent supplies for group 2 locations and a schedule for supplementary bonding resistances.
New Section 716: ELV DC power over data cabling, including Power over Ethernet. See our Section 716 guide.
Regulation 722.421.1.7.201: AFDDs are not required for EV charging equipment to BS EN 61851 with BS EN IEC 62196-2 socket-outlets or connectors.
New Chapter 81: energy efficiency, pointing to the Building Regulations and BS HD 60364-8-1. Appendix 17 deleted.

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05 · A4:2026

Appendices and model forms

Appendix 4: new reference methods for buried cables, depending on whether the cable is in direct contact with soil or in a duct; Tables 4A2, 4D4A, 4E4A, 4H4A and 4J4A revised.
Appendix 6: the notes for the person producing a condition report redrafted; signatures confirmed as those of the people who did the inspection and testing and authorised the report; FI no longer needs to be marked unsatisfactory. The forms list TN-C-S (PME) and TN-C-S (PNB) separately.
Appendix 13: guidance on cables in protected escape routes redrafted around BS 9991, BS 9999 and the fire engineer's strategy.
Appendix 1: the list of referenced standards updated.

06 · A4:2026

Often credited to A4, but older

Several rules that feel new are regularly described as A4 changes. They were already in force before A4:

AFDDs required on socket circuits up to 32 A in high rise residential buildings, HMOs, purpose-built student accommodation and care homes: A2:2022.
RCD verification by a single AC test at IΔn, and the deletion of Appendix 3 Table 3A: A2:2022.
The 250 V DC insulation resistance test after equipment is reconnected (Regulation 643.3.3): A2:2022.
SPD and AFDD fields on the model forms, and the split into separate schedules of circuit details and test results: A2:2022.
Regulation 411.3.3 redrafted into three indents, with the risk-assessment exception only for sockets in other locations: A2:2022.
RCD protection for domestic lighting circuits (Regulation 411.3.4) and the 0.95 Cmin factor behind the maximum Zs tables: the 2018 edition.
Unidirectional and bidirectional protective devices (Regulation 530.3.201): A3:2024.

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