Amendment 4 to BS 7671 lands on 15 October 2026, and for anyone who fits EV chargers it is the biggest shake-up to Section 722 since the section first appeared. Here is a practical engineering analysis of the reorganised clauses, from open-PEN arrangements and RDC-DD duties to the real-world installation decisions.

Why this matters for EV installers

EV charging is no longer a niche add-on. It is a standard domestic circuit, but it is not a standard socket circuit. The load is continuous, the equipment is outdoors or semi-outdoors, the customer expects it to work through the night without tripping the house, and the consequences of a mistake - especially around earthing - are severe. Amendment 4 does not rewrite all of that, but it tidies up the loose ends that A3 left hanging and removes some of the ambiguity that used to let installers talk themselves into a cheap shortcut.

What changed in Section 722

The headline is Regulation 722.411.4.1. The old PME exception language - the one about it being acceptable when it was "not reasonably practicable" to do anything else - has gone. That phrase caused more arguments on site than any other clause in the book. In its place, A4 gives four explicit routes: a TT earth electrode arrangement, an open-PEN protective device, a voltage-limit device, or an equivalent alternative that provides no lesser degree of safety.

What that means in practice is that you cannot simply bond the charge point earth to the PME terminal and call it done. You have to pick one of the recognised methods, document it, and be able to explain it to the customer and the inspector.

RCD requirements for EV charging circuits

The 6 mA smooth DC requirement is not new, but A4 makes the relationship between the RCD and the RDC-DD much cleaner. If the charge point has an integral RDC-DD certified to BS IEC 62955, a 30 mA Type A RCD or RCBO upstream is still the normal route. If it does not - or if you are dealing with three-phase without inherent DC isolation, or multiple units on one protective device - you are looking at Type B.

Checking the charge point datasheet before pricing the job is essential. That one line, "integral RDC-DD: yes/no", changes the cost of the protective device, the testing regime, and sometimes the whole consumer unit layout.

Protection against electric shock

Outdoors, the car body becomes extraneous-conductive-workshop. The driveway is wet more often than it is dry. A broken PEN on a PME supply can put the vehicle chassis at line-to-earth potential, and the person touching it has nowhere to step that is at true earth. That is why the open-PEN route matters. A 70 V CPC-to-earth threshold, or a 207-253 V voltage window, gives a defined safety margin instead of leaving it to site interpretation.

Open-PEN detection devices are not plug-and-play: installers must consider where the device goes, how it isolates, and what happens when it trips.

Practical observations from the field

  • Cables are getting bigger. A 7.4 kW single-phase unit on a 15-metre run can still be 6 mm², but once factoring in a warm garage, grouping, and future headroom, 10 mm² is often the preferred choice.
  • IP ratings matter more than customers think. IPX4 is the floor, but a driveway unit lives through pressure washers, frost, and impact. IP54 or IP65 is recommended.
  • Discrimination is a conversation. If the EV circuit shares a row RCD with the kitchen sockets, a fault while cooking can kill the overnight charge. A dedicated RCBO for the EV circuit is usually the right call.
  • Paperwork is part of the product. The EIC now needs to record earthing route, RCD type, RDC-DD provision, and open-PEN device details.

Conclusion: what to watch for

Amendment 4 does not make EV charging harder. It makes the decisions more explicit, which is what a good standard should do.

Watch the PME wording, confirm the RDC-DD status before quoting, size the cable for continuous loading, and ensure certificate templates are kept up to date.