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BS 7671:2018+A4:2026 is now in force: what changed

BS 7671:2018+A4:2026 is now the version of the IET Wiring Regulations that must be used. It replaced BS 7671:2018+A2:2022+A3:2024, which was withdrawn on 15 October 2026. (Wiring Matters 109; ESF BPG4)

Below: what is in force, the main changes on site, and what changes on certificates and EICRs. Each point names its source, listed in full at the end. If our sources do not cover a detail, we leave it out.

What is in force, and from when

  • A4 was published on 15 April 2026 and could be used from that day. (Wiring Matters 109; ESF BPG4)
  • From 15 April to 15 October 2026 there were two current versions of BS 7671, and either could be used. (ESF BPG4)
  • On 15 October 2026 Amendments 2 and 3 were withdrawn. From that date A4 must be used. (Wiring Matters 109)
  • The A4 document includes Amendment 3:2024 as part of the main text. (IET press release)
  • ESF says it was often assumed that work designed before a withdrawal date could still be installed after it. A4 now makes clear that a withdrawn standard no longer applies. ESF adds that contracts may be used to manage this on long-running projects. (ESF pocket guide, p.3)
  • Standards are not retrospective. An installation that complied with an earlier edition is not necessarily unsafe, and upgrading it to the current standard is not a requirement. (Wiring Matters 109)

The main changes you will meet

Chapter 57: stationary secondary batteries (new)

A new Chapter 57 covers stationary battery installations used for energy storage and supply. It applies to domestic battery systems. It excludes batteries built into products that have their own product standards, such as UPS units and emergency lighting. (ESF pocket guide, p.9)

The IET's summary of the chapter covers system design, power conversion equipment, bidirectional and hybrid inverters, and protective devices suited to two-way energy flow. It puts strong emphasis on battery location, ventilation and fire-risk mitigation. (IET press release)

For where batteries are installed, the chapter refers to BSI PAS 63100, which gives guidance on locations that reduce fire risk. (ESF pocket guide, p.9)

Section 551 also changes. Stationary batteries are treated as generating sets, not loads. New requirements cover bidirectional energy flow, and some arrangements with a source on the load side of an RCD are prohibited under defined conditions. (ESF pocket guide, p.9)

Section 716: Power over Ethernet (new)

Section 716 covers ELV DC power distributed over telecommunications cabling. ESF notes this is increasingly relevant in homes with smart home systems, access control and networked devices. (ESF pocket guide, p.10)

Within Section 716 the usual SELV and PELV limits are modified to 60 V ripple-free DC in dry locations and 15 V ripple-free DC elsewhere. PoE connections must comply with BS ISO/IEC 11801-1 and be able to carry a continuous 750 mA per contact. (IET press release)

ESF warns that equipment conforming to BS EN IEC 62368-3 might still need further consideration before the SELV or PELV requirements of BS 7671 are met. (ESF pocket guide, p.10)

Section 545: functional earthing for ICT (new)

Section 545 brings in requirements for functional earthing and functional equipotential bonding of ICT systems. In homes, it may apply where advanced communications, data systems or Power over Ethernet are present. (ESF pocket guide, p.11)

Table 51 now covers how functional earthing and bonding conductors are identified, and it clearly restricts where green-and-yellow may be used. (ESF pocket guide, p.8)

Section 710: medical locations (revised)

Section 710 has been significantly revised. Medical locations are classified as Group 0, 1 or 2. Group 2 locations need medical IT systems with a transformer and an insulation monitoring device. Two independent supplies and a UPS must be provided, as close as possible to the equipment. The changes align with IEC 60364-7-710:2021. (IET press release)

The IET's A4 model forms include a schedule of supplementary protective equipotential bonding inspection and test results, with a box for the medical location group number. (IET A4 forms)

Chapter 81: energy efficiency (new)

A new Chapter 81 covers energy efficiency, which was previously covered briefly in Appendix 17. It refers users to the Building Regulations and BS HD 60364-8-1. (ESF pocket guide, p.10)

Protective Neutral Bonding (PNB)

A4 introduces requirements and figures for Protective Neutral Bonding at Regulation 312.2.1.1. Installers must be able to recognise a PNB supply and understand how it differs from PME. (ESF pocket guide, p.6)

Other changes flagged for domestic work

  • Regulation 434.2 has been redrafted, separating overload protection from fault current protection. (ESF pocket guide, p.8)
  • Regulation 536.4.202 lists load curtailment as one of the conditions that may satisfy coordination between assemblies and overload protective devices. (ESF pocket guide, p.8)
  • Regulations 422.2 and 422.2.1: some cables that meet 422.2.1 can now run in protected corridors, and a cable inside a fire-resisting enclosure counts as outside the protected escape route. (ESF pocket guide, p.7)
  • Regulation 537.4.2 requires firefighter's switches where the building's fire strategy specifies them. (ESF pocket guide, p.11)

What it means for EICRs and certificates

Use the A4 model forms. The IET's free forms are headed BS 7671:2018+A4:2026 and dated 15 April 2026. (IET A4 forms)

FI no longer makes a report unsatisfactory

On the A4 EICR, an observation coded C3 or FI is advisory and does not affect the overall assessment. An unsatisfactory assessment means C1 and/or C2 conditions were found. (IET A4 forms; ESF pocket guide, p.11)

The FI wording has changed. It used to say further investigation was required without delay. It now says "further investigation is advised". (Wiring Matters 110)

Section K is split into two tables: one for C1 and C2 observations, and one for C3 and FI observations. (IET A4 forms)

Wiring Matters 110 says it should not be necessary to use FI in most cases. It gives two examples of misuse: a circuit that is not identified, and an insulation resistance below 1 MΩ. Both should get an appropriate classification code instead. (Wiring Matters 110)

Guidance and images on reports

Under Regulations 653.1 and 653.2, the inspector must take the Appendix 6 notes into account and give guidance to the people who receive the report. Photographs and thermal images may be attached as evidence. (ESF pocket guide, p.11)

Model form changes

  • On the EIC, EICR and Minor Works forms, the TN-C-S box is split into TN-C-S (PME) and TN-C-S (PNB). The A2 forms had a single TN-C-S box. (IET A4 forms; IET A2 forms)
  • The Minor Works earthing options are now TN-S, TN-C-S (PME), TN-C-S (PNB), TT, TN-C and IT. The A2 Minor Works form offered TN-S, TN-C-S and TT. (IET A4 forms; IET A2 forms)
  • The EICR schedule of inspection has a new item 4.23: confirmation of indication that AFDD(s) are operational, citing 421.1.7, 532.6 and 651.2(e). (IET A4 forms; IET A2 forms)
  • Minor Works ring continuity is now labelled r1 - r1, rn - rn and r2 - r2, in place of L/L, N/N and cpc/cpc. (IET A4 forms; IET A2 forms)
  • The schedules now ask for a DB/CU reference, where the A2 forms said DB reference. (IET A4 forms; IET A2 forms)

A short checklist

  • Work to BS 7671:2018+A4:2026 on everything from 15 October 2026. (Wiring Matters 109)
  • Find out whether a TN-C-S supply is PME or PNB before you tick the box. (IET A4 forms; ESF pocket guide, p.6)
  • Use FI only where the extent or limitations stop a potential safety issue being fully determined. (Wiring Matters 110)
  • Where AFDDs are fitted, confirm the indication that they are operational (EICR item 4.23). (IET A4 forms)
  • Before a battery job, read Chapter 57 and PAS 63100 on battery location. (ESF pocket guide, p.9)
  • Before PoE or ICT work, read Sections 716 and 545. (ESF pocket guide, pp.10-11)
  • On a long-running job designed to the old version, check what your contract says. (ESF pocket guide, p.3)

Practise the A4 changes

Our BS 7671 A4:2026 Practice Papers are written to Amendment 4: three 60-question papers, with an explanation and a 'where to look' reference for every answer.

Or start with the free post: BS 7671 A4:2026: 10 free practice questions with answers.

Sources

This page summarises published guidance in our own words. It does not reproduce BS 7671. Always check your own copy of the current book.