Amendment 4 to BS 7671: What electrical contractors need to know

The UK's wiring regulations have been updated. Amendment 4 to BS 7671:2018, the 18th Edition of the IET Wiring Regulations, is now published, and it's one of the most substantial updates the industry has seen in recent years.

For electrical contractors, this isn't a future consideration. It applies now to all new low-voltage electrical installations, additions and alterations to existing installations, and periodic inspection and testing work.

Here's a breakdown of what's changed and what it means in practice.

1. PNB earthing gets formal recognition

PNB earthing is an arrangement that differs from the more widely used PME setup and is now directly addressed in the regulations. For contractors working on jobs where this is the appropriate approach, formalising it in the standards brings useful clarity and removes ambiguity around compliance.

2. More flexibility for low-carbon technology

Revised guidance on switchgear and assemblies gives contractors more options when integrating low-carbon technologies, solar PV generators in particular, into new and existing low-voltage switchgear. As more projects involve on-site generation, clearer rules around what's permissible is a practical and timely update.

3. Battery storage gets its own chapter

Stationary secondary batteries, or energy storage systems, now have dedicated coverage in the regulations for the first time. Battery installations have been growing steadily across domestic and commercial projects, and the previous guidance didn't reflect that reality. This gives contractors a proper framework to work from when specifying and installing these systems.

4. New guidance for ICT systems and connected buildings

There is new guidance on functional earthing and equipotential bonding for ICT equipment and systems. As smart controls, data infrastructure and connected building technologies become standard across commercial projects, this update reflects where installations actually are today.

5. Power over Ethernet now has a dedicated section

PoE installations, where a single cable carries both power and data, are increasingly common in modern commercial fit-outs. A new section in the regulations sets out the requirements clearly, removing a lot of the grey area that previously existed around compliance.

6. A meaningful change to EICRs

A further investigation code on an Electrical Installation Condition Report will no longer automatically result in an unsatisfactory outcome. This is a more proportionate approach and has practical implications for how contractors communicate results to clients and building owners.

7. Major revision to medical locations

Section 710, which covers medical locations, has had a significant overhaul. Updated testing requirements and a new schedule for recording the resistance of supplementary protective equipotential bonding conductors mean that contractors working in healthcare environments should give this section close attention.

What to do now

The regulations are in effect, so now is the time to get up to speed. For teams already holding the 18th Edition qualification, Amendment 4 is essential CPD. For anyone who doesn't yet hold the qualification, this is a good prompt to get it sorted.

The areas most likely to affect day-to-day estimating and installation work in the near term are battery storage, PoE and the EICR changes. These are growing fast, and understanding the updated requirements will put contractors in a stronger position when pricing and delivering this kind of work.

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