18th Edition Amendment 4: what changed in BS 7671:2018+A4:2026

The biggest addition is a brand-new chapter covering stationary secondary batteries used for electrical storage and supply: reflecting the rapid growth of battery energy storage, with and without solar PV. It sets out requirements for system design, power conversion equipment, bidirectional and hybrid inverters, and protective devices suitable for two-way energy flow (important for vehicle-to-home and vehicle-to-grid setups). It also emphasises battery location, ventilation and fire-risk mitigation.

PoE now has its own section. As more devices: lighting, cameras, access control, sensors Not available are powered over data cabling, the new rules address the safe installation of PoE systems, including the heating effects of bundled cables carrying both power and data.

A new section covers functional earthing and functional equipotential bonding for information and communication technology (ICT) equipment and systems, giving clear requirements where sensitive electronic equipment needs earthing for correct operation rather than purely for safety.

Section 710 has been substantially revised, and now includes a schedule of test results for recording the resistance of supplementary protective equipotential bonding conductors : a key record for hospitals and clinical environments.

The model Electrical Installation Condition Report form has been updated:

• "Further Investigation" (FI) moves to an advisory status: an installation can now be marked satisfactory even with FI observations.
• Reports can now include photographic evidence and thermal imaging results to support findings.

• Indented lists switch from Roman numerals to letters, aligning BS 7671 with other British Standards: this shifts reference points throughout the document.
• Updates to Section 702 (swimming pools), Section 709 (marinas), Section 714 (outdoor lighting) and Section 722 (EV charging installations).
• Revisions in Part 4 and Part 5, including RCD selection (Regulation 531.3.3), isolation and switching (Section 537) and earthing arrangements (Chapter 54).
• Appendix updates, including current-carrying capacity and voltage drop (Appendix 4).

The 2382-26 qualification assesses knowledge of BS 7671:2018+A4:2026. If you're sitting the exam, you need to know the new battery, PoE, ICT earthing and medical location requirements: and the updated numbering throughout the book.

The fastest way to check you're ready is to sit a timed mock under exam conditions.