# Testing, certification & sign-off — proving it works

> A V2L arrangement is only as safe as the test that proves it. Initial verification to **BS 7671 Part 6** (with **GN3** as the companion guide) produces an **Electrical Installation Certificate**; periodic inspection produces an **EICR**. The V2L-specific proof is that the **RCD operates in both grid and V2L modes**, that the earth-fault loop is checked for **both** sources (it differs on the vehicle inverter), and — for a TT island — that the electrode resistance (**Ra**) is low and stable. Bench-verify the adapter's neutral-earth behaviour first. “Proven by test” is what turns a claim into evidence.

**Safety frame.** This is education, not an instruction to carry out work. Work connecting V2L equipment to fixed wiring is safety-critical and may be notifiable under Part P. It must be designed, installed, inspected and tested by a competent person to the current edition of BS 7671. Vehicle manufacturers generally do not sanction back-feeding fixed wiring from V2L outlets; follow manufacturer instructions.

## In short

- Initial verification to **BS 7671 Part 6**, with **GN3** as the companion guide, recorded on an **EIC** (periodic: **EICR**).
- Prove **RCD operation by test in BOTH grid and V2L modes** — a floating output can pass a tester yet give no protection until bonded.
- Check the **earth-fault loop for both sources** — the loop impedance differs on the vehicle inverter.
- For a **TT island**, confirm the electrode resistance (**Ra**) is low and stable enough to disconnect.
- **Bench-verify the adapter's neutral-earth behaviour** before relying on it.

**Where this stops:** This explains what testing proves and which certificate records it. The inspection and testing themselves are competent-person work with calibrated instruments.

## Why both modes matter

A V2L installation has **two** source conditions: on the grid, and on the car. The protection that works on one may not work on the other — a floating V2L output can pass a socket tester yet leave an RCD with nothing to operate against, and the earth-fault loop impedance on a vehicle inverter differs from the grid. So the test regime has to prove the protection in **both** modes, not just on the grid.

## The certificates that record it

- **Electrical Installation Certificate (EIC)** — for new work, recording the design, construction, inspection and test results.
- **EICR (periodic inspection report)** — confirming the installation remains safe over time.
- For a companion home battery, an additional **PAS 63100 statement of conformity** at initial verification.

## The V2L-specific checks

- **RCD operation proven by test** in both grid and V2L modes.
- **Earth-fault-loop impedance** checked for both sources (the loop differs on the inverter).
- For a **TT island**, **Ra** measured low and stable enough to disconnect.
- **Bench-verify** the adapter's neutral-earth behaviour before relying on it.

### How this is made and proven compliant

**What governs it:** BS 7671 Part 6 (Inspection & Testing) + IET GN3; BS 7671 Chapter 41 (ADS) for disconnection in both source conditions

**Who may do it:** Inspection and testing by a competent person with calibrated instruments, recorded on the appropriate certificate. Notifiable work additionally needs Part P sign-off (England).

**How compliance is demonstrated:** Electrical Installation Certificate (EIC) for new work; periodic EICR thereafter; RCD operation proven by test in both grid and V2L modes; Earth-fault-loop-impedance checked for both sources; for TT, Ra measured low and stable; Bench-verify the V2L adapter's neutral-earth behaviour

## FAQ

### Can I sign off my own V2L work?

Only if you are a competent person able to inspect and test it and certify it (or have it certified by building control). Notifiable work in England needs Part P sign-off. This is not a DIY task.

### Why test the RCD in V2L mode separately?

Because a floating V2L output gives no RCD protection until bonded, and the fault loop on the vehicle inverter differs from the grid. Proving the RCD operates on the grid does not prove it operates on V2L — both must be tested.

### What certificate do I get?

An Electrical Installation Certificate (EIC) for the new work, with periodic EICRs thereafter. A companion home battery also gets a PAS 63100 statement of conformity.

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_Author: Martin — qualified UK electrician (BEng Mech Eng; vehicle mechanic)._
_Last reviewed: 14 June 2026. Written against: BS 7671:2018 + A4:2026._
_Status: published. General information, not project-specific design advice._
_[How we source this](/methodology) — evidence hierarchy, confidence flags and source policy._

## Sources

1. IET Guidance Note 3 (Inspection & Testing) + BS 7671 Part 6 — IET/BSI (cited by reference only)
2. V2L Workshop technical reference (internal) — testing/sign-off requirements