BS 7671 Amendment 4 (2026): Complete Guide for Engineers
The Orange Book — All 12 Changes Explained with Calculator Integration
What is BS 7671 Amendment 4?
BS 7671:2018+A4:2026 is the fourth amendment to the 18th Edition of the IET Wiring Regulations, published jointly by the IET and BSI on 15 April 2026. Known as the “Orange Book”, it is the most comprehensive update since the 18th Edition was first published in 2018.
Amendment 4 introduces entirely new chapters — notably Chapter 57 for battery energy storage and Chapter 81 for energy efficiency — while substantially revising existing sections covering medical locations, functional earthing for ICT equipment, and Power over Ethernet installations.
Crucially, Amendment 4 also tightens individual competence requirements: every person doing high-risk work (Solar PV, EV Charging, EICRs) must now hold their own Level 3 qualification, ending the practice of relying solely on a Qualified Supervisor's sign-off.
All 12 Confirmed Changes
Sources: IET, BSI, NICEIC, NAPIT, EAL, ClearSafety
Chapter 57 — Battery Storage
New dedicated chapter for stationary secondary battery installations. Covers thermal runaway mitigation, safe isolation, location restrictions (prohibited in lofts/escape routes), and protection requirements.
Section 545 — ICT Functional Earthing
New section covering functional earthing and equipotential bonding for broadcast, communication, and computer network equipment. Clear distinction from protective earthing.
Section 716 — PoE & ELV DC
New requirements for distributing extra-low voltage DC via balanced data cabling. Addresses heat management in PoE cable bundles for smart buildings.
Chapter 81 — Energy Efficiency (NEW)
Brand new introductory chapter establishing an energy efficiency framework for low-voltage installations. Signals broader focus aligning with UK net zero goals.
Section 710 — Medical Locations
Major revision aligning with IEC 60364-7-710. Updated Group 0/1/2 classifications, new supplementary bonding resistance test schedule, enhanced healthcare requirements.
Firefighter's Switches
Revised guidance for emergency disconnection switches, addressing fire service requirements for rapid isolation of electrical installations.
Chapter 65 — Inspection & Testing
Clarifications to periodic inspection and testing requirements, improving consistency of condition reports and test schedules.
Regulation 521.5.1 — Ferromagnetic Enclosures
Clarified requirements: all line, neutral, and protective conductors must be grouped together in ferrous enclosures to prevent eddy current heating.
Appendix Updates — Buried Cable Data
New voltage drop and current-carrying capacity data for cables in buried ducts, enabling more accurate underground cable sizing calculations.
Condition Reports — Revised Notes
Redrafted notes for condition report producers. Signatures now required from both the person conducting the inspection AND the person authorising the report.
Individual Competence (EAS)
Every person doing high-risk work (Solar PV, EV Charging, EICRs) must hold their own Level 3 qualification. Cannot rely solely on Qualified Supervisor sign-off.
EV Supply Equipment
Revised earthing and protection requirements for EV charging installations, building on the Section 722 framework introduced in Amendment 2.
Who Does This Affect?
Impact matrix by role — save or share this table
| Change | Domestic | Commercial | Industrial | Medical | Data Centre |
|---|---|---|---|---|---|
| Chapter 57 — Battery Storage | |||||
| Section 545 — ICT Functional Earthing | — | ||||
| Section 716 — PoE & ELV DC | — | — | |||
| Chapter 81 — Energy Efficiency (NEW) | |||||
| Section 710 — Medical Locations | — | — | — | — | |
| Firefighter's Switches | — | — | |||
| Chapter 65 — Inspection & Testing | |||||
| Regulation 521.5.1 — Ferromagnetic Enclosures | — | — | |||
| Appendix Updates — Buried Cable Data | — | — | |||
| Condition Reports — Revised Notes | |||||
| Individual Competence (EAS) | |||||
| EV Supply Equipment | — | — |
5 Days to Orange Book Readiness
Free 5-day email course covering every Amendment 4 change with calculator links and a compliance action plan.
- Day 1: All 12 changes at a glance
- Day 2: Battery storage deep-dive + calculator
- Day 3: PoE cable derating + earthing
- Day 4: Medical locations + competence
- Day 5: Compliance action plan + 20% off Pro
No account required — just your email
Amendment 4 Timeline
15 April 2026
Publication — available for purchase and voluntary adoption
April — October 2026
Transition period — either current or amended standard may be used
15 October 2026
Mandatory compliance — all new installations should meet Amendment 4
How ECalPro Supports Amendment 4
Our BS 7671 calculators are being updated to incorporate all Amendment 4 changes — including new battery storage requirements, PoE derating factors, buried cable duct data, and revised medical location parameters.
Explore 27 Free CalculatorsFrequently Asked Questions
When does BS 7671 Amendment 4 come into effect?
Amendment 4 is published on 15 April 2026. There is a six-month transition period ending 15 October 2026, after which compliance with the amended standard becomes expected for all new installations.
What is the Orange Book?
The Orange Book is the informal name for BS 7671 Amendment 4, following the colour-coding tradition of the IET Wiring Regulations. Previous editions used blue (18th Edition) and green (Amendment 3). The orange cover distinguishes this consolidation.
What are the biggest changes in Amendment 4?
The headline changes are: Chapter 57 on stationary battery storage, Section 545 on ICT functional earthing, Section 716 on PoE requirements, Chapter 81 on energy efficiency, a major revision of Section 710 for medical locations, revised firefighter's switches, updated competence requirements, and new buried cable duct voltage drop data.
Do I need additional training for Amendment 4?
Competent persons should familiarise themselves with the new and revised sections. The IET, NICEIC, NAPIT, and EAL will offer Amendment 4 update courses. Individual competence requirements now mean every person doing high-risk work must hold their own Level 3 qualification.
How does Amendment 4 affect cable sizing calculations?
The new PoE cable derating requirements mean cables carrying power and data in bundled installations may need to be upsized. New buried cable duct voltage drop data in the appendices provides more accurate calculations. ECalPro's Cable Size Calculator will incorporate these changes.
Is BS 7671 a legal requirement?
BS 7671 is not itself legislation, but it is referenced by the Electricity at Work Regulations 1989 and Building Regulations Part P (England and Wales). Compliance with BS 7671 is the primary way to demonstrate that an installation meets the legal requirements.
What happens during the transition period?
During the six-month transition (April to October 2026), installations may be designed and installed to either the current standard (BS 7671:2018+A3:2024) or the new Amendment 4. After October 2026, new installations should comply with Amendment 4.
Does Amendment 4 apply to existing installations?
No. Amendment 4 applies to new installations and alterations. Existing installations that were compliant when installed do not need to be retrospectively upgraded, unless alterations or additions are made.
What are the new competence requirements?
Every person doing high-risk work (Solar PV, EV Charging, EICRs) must hold their own Level 3 qualification. You can no longer rely solely on a Qualified Supervisor's sign-off. City & Guilds 2391-52 or equivalent is required for periodic inspections.
Will ECalPro update its calculators for Amendment 4?
Yes. ECalPro will update all relevant calculators — including cable sizing, earthing, and protection — to reflect Amendment 4 requirements on publication day. Users on Professional and Team plans will have immediate access.
Related Resources
Official Sources
- Institution of Engineering and Technology (IET) — theiet.org
- British Standards Institution (BSI) — bsigroup.com
- NICEIC — niceic.com
- NAPIT — napit.org.uk
- EAL — eal.org.uk
- ClearSafety — clearsafety.co.uk