IET Code of Practice for EV Charging (5th ed) — what it adds beyond BS 7671
The IET Code of Practice for EV Charging Equipment Installation (5th Edition, 2023) is industry guidance that interprets BS 7671 for EV scenarios — not a substitute for it. For V2L the value is concentrated in Section 10, 'Vehicle as Storage', which the 5th edition expanded to cover prosumer (PEI) installations, vehicle-to-home integration and island-mode operation — the core V2L home-backup case — plus earthing where the vehicle acts as storage on a PME (TN-C-S) supply and the use of open-PEN detection devices. Section 9 carries the inspection-and-testing regime that underpins 'proven by test'. The catch is currency: the 5th edition is aligned to BS 7671:2018+A2:2022, so it predates A3:2024 and A4:2026, and its ENA G12/4 earthing alignment is now behind ENA G12 Issue 5 (2023). It must still be applied by a competent person to the current edition of BS 7671, and the contested floating-V2L-on-PME approach is only ever valid designed and proven by test; the vehicle manufacturer does not sanction this use.
In short
- The IET EV Charging CoP is guidance interpreting BS 7671 — it does not replace BS 7671 or design by a competent person.
- Section 10, 'Vehicle as Storage' is the V2L-relevant chapter: prosumer (PEI) installations, vehicle-to-home, and island-mode operation.
- It covers earthing for vehicle-as-storage on a PME supply and open-PEN detection devices — the contested floating-on-PME area, design-and-prove-by-test only.
- Section 9 is the inspection-and-testing regime (extended loop-impedance and RCD testing, Mode 3 simulators, prosumer installations) behind 'proven by test'.
- Currency caveat: the 5th ed (2023) is A2:2022-aligned — it predates A3:2024 and A4:2026, and its ENA G12/4 alignment is behind G12 Issue 5 (2023). Apply it to the current BS 7671.
Where this stops: This explains what the IET EV Charging CoP adds and where its currency lags. It is not a design recipe — interpreting the CoP and applying it to a real V2L arrangement is for a competent person.
Some details below depend on sources still being verified against the published standard, so we mark them Not confirmed rather than guess:
- The 5th-edition update is reported to reflect a narrowing of the PME open-PEN workaround in BS 7671 §722.411.4.1, but the exact indent lettering ((i)–(v)) is amendment-dependent — describe it as a narrowing of the route, not a clean 'removal of indent (i)'. (safety-critical — not treated as settled until verified)
- What (if anything) A4:2026 changed for §722 / V2X / V2H / PME / open-PEN is not confirmed — the IET's published change-lists do not name these. Do not assert any A4-specific V2X/PME change until confirmed against the published standard. (safety-critical — not treated as settled until verified)
- ENA G98/G99 exact section/clause locators are not confirmed (no direct official PDF in the card). Treat the G98/G99 references here as the notification process in general terms, not precise citations.
- An A4:2026-aligned edition of the IET EV Charging CoP is not yet published as of the review date; the 5th edition remains the current edition.
What the IET EV Charging CoP is — and is not
The IET Code of Practice for Electric Vehicle Charging Equipment Installation, 5th Edition (2023) is industry guidance on planning, installing, inspecting and testing EV charging equipment across domestic, on-street, commercial and industrial settings. It interprets and applies BS 7671 for EV-specific scenarios — supply arrangements, earthing, protective devices, charging modes and inspection-and-testing regimes. What it is not is a regulatory standard or a design recipe: it does not replace BS 7671, and it does not replace design by a competent person.
Guidance, not a substitute
When the CoP and BS 7671 appear to disagree, BS 7671 (the standard) governs the installation. The CoP helps a competent person apply it correctly — it does not authorise anything BS 7671 does not.
Electric vehicle charging installations — the special-location section the CoP interprets. A car's standalone V2L socket sits outside §722 until its output is wired into the fixed installation.
Reference only — verify against the current edition; standard text is not reproduced.
What the 5th edition adds for V2L
The 5th edition substantially expanded the bidirectional / 'vehicle as storage' material. For a V2L home-backup arrangement the value is concentrated in three places.
Section 10 — 'Vehicle as Storage'
This is the most directly V2L/V2X-relevant chapter. The 5th edition updated it for BS 7671 prosumer (PEI) requirements and vehicle-to-home integration, including island-mode operation — where the EV supplies the home with the grid disconnected. That island-mode case is exactly the core V2L home-backup scenario this site is built around.
'Vehicle as Storage' — prosumer (PEI) installations, vehicle-to-home integration and island-mode operation. The CoP's home for the V2L home-backup case.
Reference only — verify against the current edition; standard text is not reproduced.
Section 10 — earthing on PME and open-PEN detection
Section 10 also addresses earthing where the vehicle acts as storage on a PME (TN-C-S) supply and the use of open-PEN detection devices. The reason this matters is the broken-PEN failure mode: under PME, a lost combined neutral-and-earth conductor can raise exposed metalwork to a dangerous voltage, so an approved open-PEN mitigation is needed. This is the contested floating-V2L-on-PME area — the CoP guides it, but the arrangement must be designed and proven by test by a competent person, and the vehicle manufacturer does not sanction back-feeding fixed wiring from a V2L outlet.
What the diagram shows: The diagram shows two sources feeding an essential board through a changeover. From the grid, line (L) and neutral (N) arrive at the changeover; the circuit protective conductor (E/CPC) runs continuously to the board and earth bar and is never switched. From the V2L source, L and N arrive at the other side of the changeover. A neutral-earth (N–E) bond is made only when the board is on V2L, providing the floating output its single earth reference. A local earth electrode connects to the earth bar. The point: every source has exactly one neutral-earth reference, and the protective conductor is continuous in both switch states. Legend (stated in words, not colour alone): L = line/live conductor; N = neutral; E/CPC = earth / circuit protective conductor.
Earthing for vehicle-as-storage on a PME supply, and open-PEN detection devices — interpreting BS 7671 §722. The floating-earth-on-PME approach must be designed and proven by test.
Reference only — verify against the current edition; standard text is not reproduced.
The 5th-edition update is reported to reflect a narrowing of the PME open-PEN workaround in BS 7671 §722.411.4.1. We deliberately keep this as a *narrowing of the route* rather than a precise 'indent (i) was removed' claim, because the exact indent lettering shifts with each BS 7671 amendment.
The precise §722.411.4.1 indent lettering ((i)–(v)) the 5th edition narrowed is amendment-dependent and not confirmed here — treat it as a narrowing of the PME open-PEN route, not a specific indent change.
A PME earthing facility must not be relied on for an EV unless a listed open-PEN protective measure is applied. This is the regulatory hook the CoP's PME-earthing guidance interprets — design and prove by test, never a settled recipe.
Reference only — verify against the current edition; standard text is not reproduced.
Section 9 — inspection and testing
Section 9 carries the inspection-and-testing regime: extended earth-fault-loop-impedance and RCD testing, Mode 3 vehicle simulators, and testing within prosumer installations. This is the practical backbone of 'proven by test' — for a V2L arrangement, the critical addition is confirming that automatic disconnection and RCD operation still work when the source is the vehicle, not just the grid.
Inspection and Testing — extended loop-impedance and RCD testing, Mode 3 simulators, prosumer installations. The 'proven by test' regime for the V2L back-feed/islanding case.
Reference only — verify against the current edition; standard text is not reproduced.
DNO notification: two separate layers
The 5th edition expanded its DNO-notification material to cover V2G and V2H where the vehicle can export to or back-feed the installation. Two distinct layers are easy to conflate. Connection and export engages ENA G98/G99 — a notification/approval *process*. Network earthing is governed separately by ENA G12 — a network-earthing recommendation, *not* a notification process. Truly islanded V2L, physically separated by a break-before-make changeover so it cannot run in parallel or export, is generally outside G98/G99 — but whether a given changeover genuinely prevents parallel operation is a design-and-test matter for the competent person and the DNO.
Exact ENA G98/G99 section/clause locators are not confirmed (no direct official PDF in the standards card). The G98/G99 references here describe the notification process in general terms, not precise citations.
Currency — the part you must watch
The 5th edition is the current edition (no 6th exists), but its alignment is dated in two ways that matter for a 2026 V2L design.
- BS 7671 alignment: the 5th ed is aligned to BS 7671:2018+A2:2022. It therefore predates A3:2024 (wiring colours) and A4:2026 — the live edition. Apply the CoP as guidance, but design to the current BS 7671.
- ENA earthing alignment: the 5th ed aligned to ENA EREC G12/4. That was correct as published, but ENA G12 is now Issue 5 (2023) — so the CoP's earthing alignment is no longer the latest ENA issue. Flag G12/4 as dated when you cite it.
- No A4-aligned EV CoP yet: an A4:2026-aligned edition of the EV Charging CoP has not been published as of the review date. State which CoP edition and which BS 7671 amendment you used.
The 5th ed is verified as A2:2022-aligned and A4:2026 is verified as the current BS 7671. That the CoP's guidance lags the latest amendment is the reasonable inference, but the precise points where its text diverges from A4 are not enumerated in the card — confirm against the licensed texts before relying on any specific divergence.
Apply it to the current standard
Using a 2023 CoP to design against a 2026 standard is normal practice — but it is the competent person's job to bridge the gap. Where the CoP's clause references or earthing assumptions trace to A2:2022 or G12/4, they must be checked against BS 7671 A4:2026 and ENA G12 Issue 5 before they are relied on.
Where V2L ends and full bidirectional begins
The 5th edition increased its coverage of Mode 4 (off-board DC) equipment used by many true bidirectional V2G/V2H systems. That helps separate two things people conflate: a vehicle-native V2L AC socket (a plain outlet, no grid handshake) versus a full bidirectional DC architecture with a communicating charger feeding the consumer unit. This site's Phase 1 scope is the former; the CoP's Mode 4 material is the bridge to the latter.
The card flags the Mode 4 coverage point as inference; the distinction is sound engineering, but the exact extent of the 5th edition's Mode 4 treatment is not enumerated here.
How this is made and proven compliant
- BS 7671:2018+A4:2026 §722 (EV installations) and §722.411.4.1 (PME / open-PEN protective measures) — the regulatory standard the CoP interprets
- IET Code of Practice for EV Charging Equipment Installation, 5th Edition (2023) — industry guidance, Section 10 (vehicle as storage) and Section 9 (inspection & testing)
- ENA EREC G12 (LV network earthing) and ENA EREC G98/G99 (grid-parallel connection/export) — separate network-side regimes the CoP points to
The CoP is guidance for competent installers and designers; it is not a substitute for BS 7671 or for design by a competent person. Applying it to a V2L arrangement — and the resulting inlet/changeover/consumer-unit work — is normally notifiable (Part P in England; Wales/Scotland/NI differ).
- Design and verification to the CURRENT edition of BS 7671 (A4:2026), with the 5th-ed CoP applied as guidance and the edition gap acknowledged in writing
- Inspection and testing per the CoP's Section 9 regime and BS 7671 Part 6 — initial verification with an Electrical Installation Certificate
- RCD operation and earth-fault-loop impedance proven by test in both grid and V2L modes
- Confirm the actual adapter's neutral-earth behaviour on the bench before relying on it; record which CoP edition and which BS 7671 amendment were used
Confidence: Inference rolled up across the clauses cited above (the strictest state wins).
Frequently asked questions
Does the IET EV Charging CoP let me wire my car's V2L socket into the house?
No. The CoP is guidance that interprets BS 7671 — it does not authorise anything BS 7671 does not, and it is not a design recipe. A V2L back-feed/islanding arrangement on a PME supply is contested and must be designed and proven by test by a competent person; the vehicle manufacturer does not sanction back-feeding fixed wiring from a V2L outlet.
Which part of the CoP actually covers V2L home backup?
Section 10, 'Vehicle as Storage' — expanded in the 5th edition to cover prosumer (PEI) installations, vehicle-to-home integration and island-mode operation, plus earthing for vehicle-as-storage on a PME supply and open-PEN detection devices. Section 9 carries the inspection-and-testing regime behind 'proven by test'.
Is the 5th edition up to date with the current Wiring Regulations?
Not fully. The 5th edition (2023) is aligned to BS 7671:2018+A2:2022, so it predates A3:2024 and A4:2026. There is no A4-aligned EV CoP yet. Use it as guidance, but design to the current edition of BS 7671 and have a competent person bridge the gap.
The CoP aligns to ENA G12/4 — is that still current?
It was correct as published, but ENA G12 is now Issue 5 (2023), so the CoP's earthing alignment is no longer the latest ENA issue. Flag G12/4 as dated when citing it, and check the network-earthing position against the current ENA issue.
Does following the CoP mean I do not need to notify the DNO?
Not by itself. The CoP points to two separate layers — G98/G99 for connection/export (a notification process) and G12 for network earthing. Truly islanded V2L that cannot run in parallel or export is generally outside G98/G99, but whether your changeover genuinely prevents parallel operation is a design-and-test matter for the competent person and the DNO.
- Last reviewed
- 14 June 2026
- Written against
- BS 7671:2018 + A4:2026
- Reviewed by
- Martin (qualified UK electrician)
- Next review due
- 14 December 2026
General information, not project-specific design advice. Standards are cited by reference only and never reproduced. How we source this.
References & sources (5)
- IET Code of Practice for Electric Vehicle Charging Equipment Installation, 5th Edition (2023) — cited by section reference only; CoP text, tables, checklists and appendices not reproduced (© IET)
- IET Wiring Matters — Fifth edition of the IET Code of Practice for EV Charging Equipment Installation (Sept 2023)
- BS 7671:2018+A4:2026 — Requirements for Electrical Installations (IET/BSI) — cited by clause only; standard text not reproduced
- Energy Networks Association — ENA EREC G12, G98 and G99 (network earthing and connection) — G12 now Issue 5 (2023); exact G98/G99 locators not confirmed
- V2L Workshop standards reference (internal) — IET CoP and BS 7671 cards with confidence flags