# Inverter & power-converter safety for V2X — why a CE / 62109 mark is not anti-islanding proof > **BS EN 62109** is the product-safety standard for the power-electronics in PV, battery and EV-derived systems — Part 1 the general safety floor, Part 2 the inverter specifics (including stand-alone and battery-fed units). It is the standard you will see on a bidirectional charger or V2L unit's type-plate. The critical limit: a 62109 (or CE) mark proves the **converter is a safe product** — it does **not** prove the inverter will safely disconnect from a dead grid. **Anti-islanding** lives in **ENA G98/G99** and **BS 7671**, with islanding test methods in IEC 62116. **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 - **BS EN 62109-1** is the general converter safety floor; **-2** adds inverter specifics, incl. stand-alone and battery-fed units. - It is the standard most likely cited on a bidirectional charger / V2L unit's type-plate. - **A 62109 (or CE) mark is NOT evidence of anti-islanding compliance** — do not treat it as such. - Anti-islanding and grid protection live in **ENA G98/G99** and **BS 7671**, with islanding test methods in **IEC 62116**. - Part 1 Edition 2 is in draft (target Oct 2026), **not yet published** — cite the 2010 edition as current. **Where this stops:** This explains what an inverter's safety mark does and does not prove. Anti-islanding and grid protection are competent-person and DNO matters, not a product-mark claim. ## What the standard does prove BS EN 62109 is the product-safety series for power converters in PV — and, by extension, battery and EV-derived inverters that share the same DC-to-AC architecture. Part 1 sets the general safety baseline (shock, energy, fire, mechanical, thermal); Part 2 adds inverter specifics and explicitly contemplates stand-alone and battery-fed inverters. So a 62109 mark tells you the conversion hardware was designed to a recognised safety baseline. ## What it does NOT prove > **A CE / 62109 mark is not anti-islanding proof** — Part 2 covers the inverter as a product but does **not** set grid-interconnection or anti-islanding performance. Do not present a 62109 (or CE) mark as evidence that a V2X inverter will safely disconnect from a dead grid. **Figure: Grid-parallel vs islanded — the DNO-notification line.** Running a source in parallel with the grid engages ENA G98/G99 (DNO notification); a true islanded changeover that never connects the two together is generally treated as a load, outside G98/G99. _Two arrangements. On the left, the grid and the EV/source are connected together (in parallel) — this engages ENA Engineering Recommendations G98/G99, so the DNO must be notified. On the right, a break-before-make changeover switch connects the load to either the grid OR the EV/source, never both together (islanded) — a source that can never run in parallel or export is generally treated as a load and sits outside G98/G99. Whether a given changeover genuinely prevents parallel operation is a design-and-test matter for the competent person and the DNO. The exact G98/G99 clause locators are Not confirmed pending the official PDFs._ For a UK backup install, the disconnection/transfer-switching and grid-protection duty is governed by **ENA G98/G99** and the **BS 7671** wiring rules, with islanding test methods in **IEC 62116**. For a true islanded V2L (changeover, never grid-parallel), the safety comes from the changeover and earthing, not from a grid-interactive anti-islanding function. One more boundary: **BS EN IEC 62909-1** (bidirectional grid-connected converters) explicitly **excludes** PV and EV/charging-station bidirectional converters, so it does **not** govern the EV-side converter in a V2L/V2H install — don't cite it as applicable. ### How this is made and proven compliant **What governs it:** BS EN 62109-1 / -2 (converter/inverter product safety); ENA G98/G99 + BS 7671 for grid protection and anti-islanding; IEC 62116 for islanding test methods **Who may do it:** A competent person verifies the installation's protection and (where grid-parallel) the DNO agrees the connection. The product mark alone does not discharge these duties. **How compliance is demonstrated:** Confirm the converter declares to BS EN 62109-1/-2; Separately verify anti-islanding / disconnection per ENA G98/G99 + BS 7671 (not via the 62109 mark); Where islanding behaviour is claimed, look to IEC 62116 test methods ## FAQ ### My inverter is CE-marked and 62109-compliant — is it safe to island? Those marks prove product safety, not anti-islanding behaviour. Whether a system safely disconnects from a dead grid is governed by ENA G98/G99 and BS 7671 (with IEC 62116 test methods), verified by a competent person — not by the 62109 mark. ### Does a V2L socket need anti-islanding at all? A pure islanded V2L feed (changeover, never grid-parallel) is not synchronised to the grid, so the safety comes from the break-before-make changeover and the earthing — not from a grid-interactive anti-islanding function. Grid-parallel V2G is the case that engages G98/G99. ### Which 62109 edition is current? Cite the 2010 edition of Part 1 as current; a Part 1 Edition 2 is in draft (target Oct 2026) but not yet published. --- _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. BS EN 62109-2 (inverters) — BSI — https://knowledge.bsigroup.com/products/safety-of-power-converters-for-use-in-photovoltaic-power-systems-particular-requirements-for-inverters (cited by reference only) 2. ENA EREC G98 / G99 (grid protection) — Energy Networks Association (anti-islanding lives here, not in 62109)