The compliance pathway, end to end — design → install → inspect → test → certify → notify
This is how a V2L installation is proven compliant from start to finish: design to BS 7671 (including the contested earthing and the open-PEN measure) → install to the design → inspect and test (initial verification, Part 6, GN3) → certify (the EIC; periodic EICRs) → Part P sign-off (England; devolved nations differ) → notify the DNO under G98/G99 where the system can run grid-parallel → acknowledge the manufacturer-use caveat. The documents that result are not paperwork for its own sake — they are the evidence trail that turns a claim into a safe, lawful installation.
In short
- Design — BS 7671, including the contested earthing and the open-PEN protective measure.
- Install → inspect → test — to the design; initial verification to Part 6 with GN3.
- Certify — an Electrical Installation Certificate (EIC); periodic EICRs thereafter.
- Part P sign-off (England; Wales/Scotland/NI differ) and, where grid-parallel, DNO notification (G98/G99).
- The documents are the evidence — and the manufacturer's non-sanction of back-feeding from V2L is acknowledged throughout.
Where this stops: This shows the whole pathway end to end. Every stage is competent-person work — the value of the documents is that they are the evidence the work was done correctly.
The pathway, stage by stage
- Design — to BS 7671, resolving the earthing (the open-PEN measure under §722.411.4.1, and the independent means of earthing under §551.4.3.2.1), the changeover and the protection.
- Install — to the design, by a competent person.
- Inspect & test — initial verification to Part 6 (with GN3): prove RCD operation in both grid and V2L modes; check the fault loop for both sources; for TT, confirm Ra.
- Certify — issue the Electrical Installation Certificate; schedule periodic EICRs.
- Part P sign-off — self-certify under a competent-person scheme, or have building control check (England; Wales/Scotland/NI differ).
- Notify the DNO — under G98/G99 where the system can run grid-parallel (a true island is generally outside this).
- Acknowledge the manufacturer caveat — vehicle makers generally do not sanction back-feeding fixed wiring from V2L outlets.
What the diagram shows: A single-sheet assembly of the outbuilding TT scheme. Power: grid line/neutral (L/N) and V2L L/N feed an interlocked two-pole contactor changeover (KM1 grid / KM2 V2L) into a small essential board. Control: a scheduled smart relay drives the interlocked coils, fail-safe to grid. Earthing: a local electrode feeds the outbuilding earth bar and all CPCs continuously; the PME earth is not exported; the V2L neutral-earth bond is switched in via a KM2 auxiliary contact; an RCD protects the board. The single key point: the load is dropped, the source swapped, and re-energised — never bridged — and the installation is earthed in every state. Legend (stated in words, not colour alone): L = line/live conductor; N = neutral; E/CPC = earth / circuit protective conductor.
Why the documents are the point
Each stage produces a document — the design, the EIC, the EICR, the Part P notification, the DNO acceptance, the PAS 63100 statement for a companion battery. Together they are the evidence trail: the difference between “it should be safe” and “here is the proof it was designed, installed and tested correctly.” That evidence is exactly what makes the engineering — and the kit you choose to realise it — trustworthy.
How this is made and proven compliant
- BS 7671 (design, installation, verification, certification — Parts 5, 6; §722; §551)
- Approved Document P (notification/sign-off, England) and devolved equivalents
- ENA G98/G99 (DNO, where grid-parallel); manufacturer documentation (V2L-use caveat)
Designer, installer, inspector/tester, the Part P certifier and (where grid-parallel) the DNO — a multi-party competent-person process from end to end.
- Design recorded; installed to the design; initial verification + EIC; periodic EICR
- Part P sign-off (scheme or building control) in England
- DNO notification/acceptance under G98/G99 where grid-parallel; manufacturer caveat acknowledged
Confidence: Inference rolled up across the clauses cited above (the strictest state wins).
Frequently asked questions
What's the shortest honest answer to 'is my V2L install compliant'?
It is compliant when it has been designed to BS 7671, installed to that design, inspected and tested (RCD proven in both modes), certified (EIC), signed off under Part P where notifiable, and accepted by the DNO if it can run grid-parallel. The documents are the evidence.
Do I need all of this for a small backup board?
The work is normally notifiable (a new circuit, changeover or consumer-unit change), so yes — design, installation, test, certification and Part P sign-off apply. The DNO step only applies if the system can run grid-parallel.
Does the manufacturer approve this use?
Generally no — vehicle makers do not sanction back-feeding fixed wiring from a V2L outlet. That caveat is acknowledged throughout; the safe route is a competent-person design, proven by test.
- 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 (3)
- BS 7671:2018+A4:2026 (Parts 5 & 6; §722; §551) — IET/BSI — cited by clause only
- Approved Document P — Electrical safety (GOV.UK)
- IET Guidance Note 3 (Inspection & Testing) — IET — the verification procedures