Open PEN protection is a protective function that watches the supply for a broken combined earth-and-neutral (PEN) conductor and disconnects the charge point if one is detected — including disconnecting the car from the installation’s earth. It exists because the fault it answers is invisible: the charger keeps working, the car keeps charging, and only the earthing reference has gone wrong.
Key Takeaways
- Open PEN protection detects a broken combined earth-and-neutral conductor and disconnects the charge point, car included.
- It can live in the charge point — only where the maker’s specification states it — or as a separate device in the installer’s design.
- It is not an RCD and not a repair; the network operator fixes the supply.
- EVDANCE pages state no PEN protection for any model: for UK fixed installs, confirm the design answer in writing before fitting.
What It Does, in Plain Terms
On a TN-C-S supply, a lost PEN conductor can leave earthed metalwork — a charging car’s body included — pulled away from true earth. A device providing open PEN protection monitors for that condition while the vehicle is connected. When it detects it, it opens the connection: the session stops, and the car is separated from the faulty earth. Two limits define it honestly: it detects and disconnects but repairs nothing — the broken conductor in the network is the network operator’s to fix — and it answers this one fault, not the installation as a whole, which is designed under the wiring regulations and the IET Code of Practice for EV charging equipment installation.
Where the Protection Can Live
| Where it sits | How you know it is there | Notes |
|---|---|---|
| Built into the charge point | The manufacturer’s specification for the exact model states open-PEN or PEN fault protection | Worked example: our piece on whether the Tesla Wall Connector has PEN fault protection |
| A separate protective device at the consumer unit | The installer’s design and certificate record it as part of the charging circuit | The route used where the chosen charge point does not carry the function itself |
| Not required in this form | The property’s earthing arrangement is a different type, and the design answers its own questions | Established per property at survey — never assumed from a neighbouring installation |
What It Is Not
- Not an RCD. An RCD responds to current leaking where it should not; a lost PEN raises the earthed metalwork itself, without that leakage. Our guide to RCD protection for EV chargers keeps the two separate — an installation can need both.
- Not a repair. After it operates, the supply fault still exists — the network operator fixes the conductor. The protection has kept the car out of the fault meanwhile.
- Not a substitute for design. It is one component of an installation the electrician designs, tests and certifies — circuit, protective devices and earthing together, of the kind an approved EV charger installer in the UK delivers.
The Buying Check — and the EVDANCE Position
The function exists only where a specification states it, so the buyer’s check is documentary: ask for the model’s specification and its claimed protective functions, in writing. This is where precision matters for our own range. EVDANCE’s product pages do not state PEN fault protection for any model: the EV-ACT3204PE (22 kW three-phase wallbox, tethered Type 2 cable, RFID and app, IP66, CE) and the EV-ACS3205PE (22 kW three-phase portable, CEE 32A plug, Type 2, IP66) are specified on those facts and no more. That is not a defect claim — it is a design instruction: for a UK fixed installation on a combined-conductor supply, the PEN question is answered by the installation design (commonly the separate-device route above), and the unit’s position is confirmed with the installer and, where needed, with us in writing via contact us before fitting.
Frequently Asked Questions
Does every UK home charger need open PEN protection?
It depends on the property’s earthing arrangement. On combined-conductor (TN-C-S) supplies — most UK homes — the design must answer the PEN question somehow; on other arrangements the question takes a different form. Your installer establishes the arrangement at survey and records the answer.
Can open PEN protection be added if my charger does not have it?
That is a standard design route: a separate protective device fitted as part of the charging circuit by the installer, who designs and certifies it. It is installation work, not an accessory to clip on.
Will I know if it has operated?
The session stops and the unit shows its fault state. What it has detected is a supply problem, so the next step is the network, not the charger: the network operator repairs the conductor, and the installer can confirm the installation side.
Related Reading
- Does the Tesla Wall Connector Have PEN Fault Protection? (UK)
- RCD Protection for EV Chargers: Type A, Type B and 6 mA DC Detection Explained
- How to Become an Approved EV Charger Installer in the UK (OZEV)
- UKCA vs CE for EV Chargers Sold in Great Britain
