BS 7671 Amendment 4 is now the only wiring standard

What Amendment 4 actually contains

The IET describes Amendment 4 as incorporating Amendment 3:2024 into the main document and adopting further CENELEC and IEC material. The changes most relevant to homes with solar, batteries or rented property are these:

• A new chapter on stationary batteries. The IET's 15 April announcement lists a new chapter on stationary secondary batteries, covering system design, bidirectional and hybrid inverters, battery location, ventilation and fire-risk mitigation. NICEIC identifies it as Chapter 57. This is the part of A4 that matters most to a solar household adding a hardwired battery.
• Protective neutral bonding. NICEIC reports that PNB is recognised in BS 7671 for the first time and can be selected as an earthing arrangement on certificates.
• AFDDs, redefined buildings. "Higher risk residential buildings" become high-rise residential buildings, defined as over 18 metres or more than six storeys. NICEIC states that arc fault detection devices are required on socket-outlet circuits up to 32 A in high-rise residential buildings, HMOs, purpose-built student accommodation and care homes, and that BS 7671 does not require them on battery storage circuits.
• Inspection reports. EICR observations are split so that C1 and C2 make a report unsatisfactory and C3 and FI do not, according to NICEIC. For landlords this could mean fewer reports failing on an FI code alone, although a C1 or C2 still has to be put right.
• Other new sections. Power over Ethernet (Section 716), functional earthing for ICT equipment, and a major revision of Section 710 for medical locations. None of these touches a typical solar install.

What it means for plug-in solar

A plug-in kit is lawful to plug into a 13A socket because of SI 2026 No. 848, which amended the Plugs and Sockets etc. (Safety) Regulations 1994 and the ESQCR 2002 from 27 August 2026, together with EREC G98 Issue 2 Amendment 1. The kit also has to show Compliant on the ENA G98 Type Test Register, checked by model code. That position is the same on 18 October as it was on 14 October.

What BS 7671 says about it is less settled. The IET's own announcement of Amendment 4 and its guidance on the transition do not describe a plug-in solar provision. On the IET's Engx forum, electricians discussing A4 read Regulation 551.7.2 as still pointing a generating set at a dedicated circuit, and some argue the standard will need a further amendment to deal with plug-in devices. The trade view, in short, is that the wiring rules have not yet caught up with the plug-in route.

Who notices the change, and how

Households with a solar install booked. Any new work, including a hardwired battery or a dedicated circuit for a kit that is not on the register, will now be certified to A4. If the job was designed before 15 October, ask your electrician which edition the certificate will reference, because both are allowed for that work.

Landlords. The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require an EICR at least every five years. Reports produced from 15 October 2026 are to A4, according to NICEIC, so the next one for most rented homes will use the new coding. If a tenant asks to use a plug-in kit, the EICR is the natural document to check the circuit against.

Renters. Nothing new is asked of you. The register check, the self-notification to your network operator and the conversation with your landlord are unchanged. The renter guide covers all three.

What I would do about it

1. Check the register before anything else. If your kit's model code shows Compliant on the ENA G98 register, Amendment 4 does not change your plan.
2. Look at the socket you intend to use. A scorched, loose or old socket on a circuit without RCD protection is worth an electrician's visit whatever the kit, and the BS 7671 page sets out what to look for.
3. If you are adding a hardwired battery, ask about the new battery chapter. Location, ventilation and fire risk are now addressed directly, so expect the design conversation to include them.
4. If you let a property, diary the next EICR. It will be to A4, and the FI change may alter the outcome.

I will update this page if the IET publishes guidance on plug-in devices or a further amendment. Corrections go on the changelog.

Common questions

• When did BS 7671 Amendment 4 become mandatory?
  On 15 October 2026. The IET published BS 7671:2018+A4:2026 on 15 April 2026 with a six-month transition, and states that from 15 October 2026 Amendment 4 must be used and the previous edition (A2:2022+A3:2024) is withdrawn.
• Did Amendment 4 make plug-in solar legal?
  No. The plug-in route became lawful on 27 August 2026 through SI 2026 No. 848, which amended the Plugs and Sockets Regulations 1994 and the ESQCR 2002, together with the G98 amendment. A kit must show Compliant on the ENA G98 Type Test Register. The IET's published material on Amendment 4 does not describe a plug-in solar provision.
• Can work started before 15 October still use Amendment 3?
  NICEIC states that work designed before 15 October 2026 can still be completed to the earlier edition. New designs and new inspection reports from that date use Amendment 4.
• Does Amendment 4 change anything for solar batteries?
  Yes. It adds a new chapter on stationary secondary batteries covering system design, bidirectional and hybrid inverters, location, ventilation and fire-risk mitigation. Batteries remain outside the plug-in route, so a battery is a hardwired job for an electrician.