Section 722 EV Charging — What A4:2026 Actually Changed

Section 722 — Electric Vehicle Charging Installations — was first introduced into BS 7671 in the 17th Edition and has been re-edited at almost every amendment since. The headline A4:2026 change is to Regulation 722.411.4.1 on the use of a PME supply: the long-standing exception worded around "not reasonably practicable" has been deleted, and indent (a) is gone, so the permitted PME routes are now the explicit protective-device and earth-electrode options at (b) to (e). A4:2026 also makes changes to external influences, RCDs, socket-outlets and connectors, and aligns the section with the new bidirectional-energy rule at Regulation 551.7.1(c).

The reorganisation is not cosmetic. A4:2026 brings Section 722 into line with the latest IEC 61851 series and with the Electric Vehicles (Smart Charge Points) Regulations 2021. It also tightens the link between Section 722 and the rest of BS 7671 — particularly Chapter 41 (protection against electric shock), Chapter 53 (protection, isolation, switching) and the redrafted Regulation 551.7.1 on bidirectional energy flow where solar PV or battery storage is co-located with V2G.

Residual Direct Current Detection — detection of a smooth DC residual current of 6 mA or more on the AC side of an EV charge point — is the single clause that has caused more confusion than any other in Section 722. A4:2026 does not abandon the requirement; it sharpens the wording and clarifies how the duty interacts with the upstream RCD.

Regulation 722.531.3.101 requires that, for AC charge points, protection against DC fault currents be provided either by a Type B RCD or by an RDC-DD that disconnects when a smooth DC residual current of 6 mA or more is detected. BS 7671 defines the RDC-DD as a device having at least the functionality of detection and evaluation of 6 mA DC residual currents and switching of the monitored circuit, and the device standard is BS IEC 62955:2018. The RDC-DD is permitted as an integral function of the charge point — and is how almost every commercially available 7.4 kW UK-market unit satisfies the clause. Where the RDC-DD is integral, the upstream RCD may be Type A rather than Type B.

The PME (Protective Multiple Earthing) arrangement — known formally in BS 7671 as TN-C-S — is the default UK domestic supply, and the arrangement most likely to cause a dangerous touch voltage on outdoor metalwork during an open-PEN fault. An EV parked on the driveway is bonded to the vehicle chassis through the charging cable; if the supply PEN opens while load is drawn, the vehicle body can rise to a voltage close to line potential. Section 722 has restricted PME for EV charging since the 17th Edition; A4:2026 retains the restriction with refined exception conditions.

Regulation 722.411.4.1 prohibits the use of a PME earthing facility as the means of earthing for the protective conductor contact of a charge point located outdoors (or one that might reasonably be expected to charge a vehicle located outdoors) unless one of the methods (b) to (e) is used. A4:2026 deleted the former indent (a) and the "not reasonably practicable" wording, so the four explicit routes below are now the only compliant ways to keep — or step away from — the PME earth.

1. Method (b) — TT route. Connect the main earthing terminal to an installation earth electrode via a protective conductor complying with Regulation 544.1.1, sized so that the voltage between the MET and Earth during an open-circuit PEN fault does not exceed 70 V RMS. Annex A722, Item A722.3 gives the formula for the maximum earth electrode resistance (and notes electrodes above 200 Ω may be unstable).
2. Method (c) — open-PEN protective device. Retain the PME facility but fit a device that disconnects the vehicle from the live conductors and protective earth within 5 s when the voltage between the circuit protective conductor and Earth exceeds 70 V RMS due to an open-PEN fault (it need not operate if the excess lasts under 4 s). The device must provide isolation, be selected per Table 537.4, and reset only when CPC-to-Earth voltage is back below 70 V RMS.
3. Method (d) — voltage-limit device. A device that disconnects within 5 s when the utilisation voltage between line and neutral rises above 253 V RMS or falls below 207 V RMS, again providing isolation and selected per Table 537.4. This monitors the supply voltage envelope rather than the CPC-to-Earth voltage directly.
4. Method (e) — equivalent alternative device that gives no lesser degree of safety than (c) or (d), also providing isolation and selected per Table 537.4. Equivalent functionality may be built into the charging equipment itself.

The PME restriction does not apply to TN-S supplies (separate earth back to the distribution transformer) — TN-S installations carry no open-PEN risk and may earth the charge point through the existing arrangement. It also does not apply to Protective Neutral Bonding (PNB) supplies, but PNB is a specific DNO arrangement and should be confirmed in writing before relying on it.

There is also a fifth, less common route that sidesteps the PME question entirely: electrical separation under Regulation 722.413. Here a single electric vehicle is supplied from one unearthed source through a fixed isolating transformer complying with BS EN 61558-2-4 — only one charging point may be supplied per transformer (see Regulation 722.413.1.2). Note BS 7671 cautions (NOTE 3 to 722.411.4.1) that creating a TT system as an alternative to PME may itself be inappropriate where sufficient separation from buried metalwork connected to the supply PEN cannot be achieved.

A charge point on a UK driveway must survive rain, hose-down, dust, frost, salt spray near the coast, and accidental impact from car doors, bicycles and tools. The IP rating flows from the external influences assessment in Chapter 32 and Section 522: water splashes from any direction (classification AD4) demand a degree of protection of at least IPX4, which is the floor for an outdoor charge point. A4:2026 made changes to the external-influences requirements of Section 722; the practical specification has tightened above the minimum.

Where the charge point is mounted inside a dry, weatherproof, dust-free garage, the indoor IP regime applies and the minimum may be relaxed to IP21. If the garage is used as a wet workshop, has an unsealed roof, or has a permanently open vehicle door, treat it as outdoor for the purpose of Section 722.

Cable selection for an EV charge point is a standard BS 7671 design exercise, but several factors make the outcome materially different from a domestic socket circuit. The continuous duty cycle of charging, ambient temperature in the run to an outside wall, the protective device type, and the earthing arrangement (TT versus PME) all push the cable size up.

Bidirectional charging — Vehicle-to-Grid (V2G), Vehicle-to-Home (V2H) and Vehicle-to-Load (V2L) — is the headline new content in A4:2026. Previous editions implicitly assumed power flow from grid to vehicle; A4:2026 explicitly recognises that the vehicle may also act as an export source under control of an inverter integral to or external to the charge point.

A bidirectional charge point behaves like a hybrid between a Section 722 charge point and a generator interface. It must meet the EV charging duties when importing and the generator-side duties when exporting. A4:2026 redrafted Regulation 551.7.1 and added a new indent (c) requiring a suitable protective device wherever energy flow is bidirectional — the same rule that now governs PV and battery inverters that can export. The practical effect: protective devices, isolation, anti-islanding and loss-of-mains detection must satisfy the more onerous of the import and export cases.

The choice between Type A upstream (paired with an integral RDC-DD inside the charge point) and Type B upstream (covering DC fault current on its own) is the single most important protection decision on an EV charging install. Both routes are permitted by A4:2026; the choice is driven by the charge point hardware, the wider installation, and the cost-and-discrimination trade-off.

Discrimination — the principle that a fault should be cleared by the nearest protective device only — is a normal Chapter 53 duty, but for EV charging it carries a specific risk. A Type A RCD on the EV circuit will sit in the same consumer unit as the other house RCDs. A fault on the EV circuit must not trip the whole house, and a fault elsewhere must not trip the EV circuit and disrupt charging overnight.

Every new EV charging installation requires an Electrical Installation Certificate (EIC) under Part 6 of BS 7671. The EIC is the same form as for any new addition, but Section 722 imposes specific items that must be recorded — and A4:2026 has tightened the wording on several of them.

1. Earthing arrangement — TN-C-S (with the exception condition under 722.411.4.1 explicitly named), TT (with the local earth electrode resistance recorded), or TN-S (with the supply earth confirmed in writing by the DNO).
2. Protective device — the type, rating and breaking capacity of the upstream RCD or RCBO, and the type (Type A, Type B) and tripping current (typically 30 mA).
3. RDC-DD provision — whether the charge point includes an integral RDC-DD to BS IEC 62955, and the manufacturer model number.
4. Open-PEN protection — if the PME earthing route under 722.411.4.1(c) or (d) is used, the device model number, the disconnection threshold (70 V RMS CPC-to-Earth, or the 207–253 V RMS band), and confirmation it provides isolation and is selected per Table 537.4.
5. Inspection results — visible inspection of cable terminations, glands, IP rating, IK protection, mechanical security, identification of circuits, and confirmation of correct labelling at the consumer unit.
6. Test results — continuity of CPC, insulation resistance (Line-Earth, Neutral-Earth and Line-Neutral with the charge point disconnected), polarity, earth fault loop impedance Zs, RCD operating time at IΔn and 5×IΔn, and where applicable the RDC-DD test using the procedure prescribed by the manufacturer.
7. Functional test — confirmation that the charge point energises the vehicle correctly, that the contactor closes only when the control pilot is established, and (for V2G) that loss-of-mains detection operates correctly.