What changed in Amendment 4 to BS 7671?

The changes that matter most to a householder are the new dedicated requirements for stationary battery storage systems, a major revision of Section 710 on medical locations, and the conditions under which a plug-in solar device may be connected to a UK socket circuit². The standard is listed as current, with an ICS code of 91.140.50 for electricity supply systems².

For a household, the practical effect is that any generation or storage equipment added to an existing installation is now designed, specified and verified against a single current document. That document is the reference point an installer, a certification body and a building control officer all work to.

What Amendment 4 changes to how systems are designed and specified

Amendment 4 introduces updates that affect how electrical systems are designed, specified and implemented, including considerations around battery storage systems and evolving safety requirements⁷. The scope of BS 7671 itself covers the design, erection and verification of electrical installations, including additions and alterations to existing installations, and the requirements for design, installation, inspection, testing, verification and certification⁸.

The headline addition is a dedicated Chapter 57 for stationary secondary battery installations⁴. This is the first time the wiring regulations have carried a chapter aimed specifically at stationary battery storage, and it means a home battery is now specified against its own set of rules rather than being treated as a generic addition to a circuit. The covered technologies in the amendment include solar photovoltaic systems, battery energy storage, Power over Ethernet (PoE) and electrical installations in medical locations³.

A major revision of Section 710 (Medical Locations) sits alongside the domestic changes, including new requirements for recording resistance of supplementary protective equipotential bonding conductors². That section is unlikely to touch a dwelling, but it shows the breadth of the amendment.

The amendment also carries forward the direction set by Amendment 3:2024, which added two new definitions to Part 2 of BS 7671 in addition to a new regulation in Chapter 53¹⁰. Those definitions and that regulation addressed the issue of electrical sources applied to the load side of protective devices, which is the technical problem that arises when generation feeds power into a circuit from the wrong end¹¹.

For a household, the design consequence is that the protective devices in a consumer unit must be selected for the installation being worked on, and the installer must establish whether the devices being installed are bi-directional or unidirectional¹⁰. A device that cannot carry fault current in both directions is not suitable where generation feeds back into the circuit.

Plug-in solar: the conditions for safe connection to UK installations

Plug-in solar is the area where Amendment 4 meets the newest product category. Official interim product specification sets out the conditions. Plug-in solar intended for connection to UK sockets must use plugs designed to BS 1363-1¹². The device must be connected only to socket circuits and not to circuits supplying lighting or other fixed equipment¹². It must be connected to a UK mains socket solely by the manufacturer-supplied plug¹².

The device must also comply with the technical requirements for connection and parallel operation with low voltage distribution networks in Great Britain, which means Engineering Recommendation G98 Issue 2 Amendment 1¹².

The joint statement from ECA, Electrical Safety First, IET, NICEIC and SELECT notes that Amendment 3:2024 to BS 7671:2024 addressed the issue of electrical sources applied to the load side of protective devices¹¹. That is the technical groundwork that makes a socket-connected generator addressable under the wiring rules at all.

NAPIT states it supports the principle of permitting compliant plug-in solar products to be connected to UK electrical installations, subject to conditions, and that enforcement prevents unsafe or non-compliant imports entering the UK market¹³. NAPIT is a certification body and training provider¹⁴.

Application of the specification to Northern Ireland is subject to further consideration and may require amendment⁵. That is a live difference between the nations and it matters to a household in Northern Ireland considering a plug-in product.

Older homes: wiring and RCD limitations when generation feeds back

The IET has warned that some older homes may have wiring or protection devices not designed for electricity flowing back into a circuit, and that older consumer units may contain RCDs that may not trip properly, meaning they do not offer shock protection when a fault occurs¹⁵. That warning is the single most important limit on retrofitting generation to an older installation.

The technical reason sits in BS 7671:2018 Section 722, where further requirements apply to both Type A and Type B RCDs to take account of DC fault current¹⁶. A DC fault current can blind certain RCD types, which is why the type matters as much as the rating.

Where equipment does not comply with British Standards, the resulting degree of safety of the installation must be not less than that obtained by compliance with BS 7671:2018+A2:2022¹⁷. That is the fallback rule: non-standard equipment is not automatically barred, but the safety outcome must be equivalent.

All electrical work should follow the safety standards in BS 7671, and the standard applies to all new build and properties being rewired¹⁸. Solar panel installations must meet the requirements of BS 7671 to be considered safe and compliant²⁰.

For a household, this means the state of the existing installation, not the new equipment, is often the deciding factor. A generation or storage device added to a circuit whose protective devices were never selected for reverse current is a design problem before it is a product problem.

Inspection, testing and who can certify the work

BS 7671 covers requirements for design, installation, inspection, testing, verification and certification of electrical installations⁹. Work carried out by a registered electrician will meet the UK national standard, BS 7671²¹. That is the assurance a competent person scheme is built to give.

Building regulations approval is a separate track. Applications are required for new build, property extensions and also work of a minor nature, particularly installing fittings, new heating appliances and systems, altering a building's structure, changing the use of a building or building work affecting fire safety, and in some instances repair work²². Replacing windows and doors is also covered alteration work²³.

Installers accredited by bodies such as NAPIT can submit a building regulations application on the householder's behalf²⁴. That is the route by which a self-certifying installer notifies the work rather than the householder making a separate application.

The nations differ. In Scotland, building regulations were revised to amend Section 0 General, Section 2 Fire, Section 3 Environment and Section 4 Safety in the technical handbooks for use from 6 April 2026, and the Building (Scotland) Amendment Regulations 2025 changed Regulation 8 with new 8(4)(k) and 8(4)(l) and updated definitions²⁵. A household in Scotland therefore works to a separate technical handbook track alongside the UK-wide wiring standard.

The Boiler Upgrade Scheme (England and Wales) Regulations 2022 cite BS EN ISO/IEC 17065:2012 for conformity assessment of bodies certifying products, processes and services under Regulation 4(1)(a)(i)²⁷. That is the certification architecture that sits behind product approval for funded work.

NAPIT's role, accreditation and what happens when work is non-compliant

NAPIT is a certification body and training provider¹⁴. Its complaint process applies when a company certificated by NAPIT has been contracted or subcontracted to carry out work covered by the scope of their certification⁶. It is NAPIT's policy to review all complaints with impartiality⁶.

The process has conditions. The consumer or consumer representative must have formally contacted the member directly and allowed a minimum of 14 days for the member to acknowledge the complaint⁶. NAPIT requires evidence of authority for a representative to act on behalf of a consumer⁶. Once the complaint is received, receipt is acknowledged within 5 working days, and any communication will be responded to within 10 working days unless this is outside NAPIT's control⁶. Where further investigation is required, this may be completed via desktop review or inspection⁶.

Eligibility turns on the nature of the failure. A complaint can be raised if work undertaken does not comply with Building Regulations, British Standards, MCS published standards, or has resulted in an unsafe situation, and the issue must first be raised directly with the installer²⁴.

If rectification work is not done satisfactorily or no resolution is agreed, the installer may jeopardise their NAPIT certification²⁴. Non-routine matters that fall outside of procedure will be referred to the NAPIT Compliance Panel⁶. Where sanctions are imposed onto a member's certification, NAPIT can share the status of the membership, but the specific details as to any sanctions imposed will not be disclosed to the consumer or consumer representative⁶.

Two exclusions are worth knowing. The process does not cover work carried out as part of the plan for a new build property constructed within the last ten years⁶. NAPIT also cannot remove personal data whilst the complaint is ongoing, or if a guarantee related to the complaint has not yet expired⁶.

NAPIT states plainly that it will not compensate or reimburse monies in regard to non-compliant work²⁴. A householder's remedy through the scheme is rectification by the member, not payment.

What this means for a household's energy independence

Amendment 4 widens what a home can legally connect and store, and it does so by tightening the design rules around the point of connection. A home battery now has its own chapter⁴. A plug-in solar device has a defined route to a socket circuit, with a specified plug standard and a network standard to meet¹². Solar installations must meet BS 7671 to be considered safe and compliant²⁰.

The dependence that remains is on the installation itself and on the people who certify it. The grid connection is still governed by Engineering Recommendation G98 for parallel operation⁵. The protective devices in the consumer unit must be right for reverse current, and in some older homes they are not¹⁵. Certification runs through a competent person scheme and a building control notification, and the scheme's complaints process rectifies work rather than paying for it²⁴.

For a household, the sequence the rules imply is: establish the state of the existing wiring and protective devices, confirm the equipment meets the current standard, and confirm who is certifying the work and notifying building control. The rules set what is permitted; they do not choose a product or an installer.