If you’re installing EV chargers in 2026, one question keeps coming up:
“When is PEN fault protection actually mandatory?”
Not recommended. Not best practice. Mandatory.
This guide explains when open PEN protection is required under BS 7671 for EV installs, when it may already be built into the charger, and when you need a dedicated protection method.
Quick Answer: PEN fault protection is mandatory for EV chargers installed on PME (TN-C-S) supplies where an open PEN could create a dangerous touch voltage. In most outdoor domestic EV installs on PME, you must use either a charger with compliant built-in open PEN detection or a dedicated PEN/PME fault detection device.
🧭 Jump to:
1. On a PME (TN-C-S) Supply – This Is the Trigger
PEN protection becomes mandatory when:
- The supply is TN-C-S (PME), and
- An open PEN could create a dangerous touch voltage, and
- The EV charger is connected in a way that exposes users to true earth potential.
In domestic settings, that usually means an outdoor wall-mounted charger on a PME intake.
Regulation Reminder: BS 7671 requires that installations prevent electric shock in the event of a supply PEN conductor failure where risk exists. The regulation is outcome-based - you must provide a compliant protection method.
2. Outdoor Installations = High Likelihood of Mandatory Protection
When the EV charger is external:
- The user is standing on the ground.
- The vehicle body is conductive.
- PME earth is effectively exported outside the building’s bonding zone.
That combination is why most outdoor EV installs on PME require open PEN protection in 2026.
3. What If the Charger Has Built-In Open PEN Detection?
If the EVSE includes certified open PEN detection compliant with current standards, additional external PEN protection may not be required.
However:
- You must verify manufacturer documentation.
- The detection must meet current wiring requirements.
- The installation must match the charger’s tested configuration.
If any doubt exists, installers often prefer a dedicated protection unit to keep compliance straightforward.
When Is It Not Mandatory?
PEN fault protection is generally not mandatory when:
- The property is on a TT supply.
- The charger is installed entirely within a bonded internal zone.
- A fully compliant alternative earthing arrangement is implemented.
That said, most standard domestic outdoor PME installs fall into the “mandatory” category.
3-Phase & Commercial EV Installations
On three-phase PME supplies, imbalance during an open PEN event can create even greater voltage instability.
For commercial sites with multiple charge points, PEN fault protection is typically required unless the system design provides a compliant alternative method.
Installer Shortcut: For commercial or 3-phase EV installs on PME, using a dedicated 3-phase PME fault detection unit removes ambiguity and simplifies inspection sign-off.
PEN Fault Protection Units for Mandatory EV Installs (2026)
If open PEN protection is required on your installation, choose a unit matched to the supply type and charger rating:
Domestic Single-Phase Outdoor EV (Most Common Scenario):
👉 IP65 PME Consumer Unit – 40A Type A RCBO + SPD
👉 IP65 PME Consumer Unit – 40A Type A RCBO (No SPD)
Three-Phase & Commercial EV Installations:
👉 3-Phase PME Fault Detection Unit – 40RSP
👉 3-Phase PME Fault Detection Unit – 63A with SPD
All units provide monitored disconnection in the event of supply PEN failure on TN-C-S (PME) systems and are suitable for 2026-compliant EV installations.
FAQs
Clear answers to common compliance questions.
Is PEN fault protection legally required?
It is required where BS 7671 determines protection against electric shock in the event of a PEN failure is necessary. For most outdoor PME EV installs, this means yes.
Can I rely only on an RCD?
No. RCDs detect residual current imbalance. They are not designed to detect open PEN conditions.
Do all EV chargers need external PEN protection?
No. Some have compliant built-in detection. Always verify before omitting additional protection.
Final Word
If you’re installing an outdoor EV charger on a PME supply in 2026, assume PEN fault protection is mandatory unless you have clear evidence otherwise.
- Check the earthing system.
- Check the EV charger specification.
- Apply a compliant protection method.
👉 Stay compliant and inspection-ready - compare PME Fault Detection Units for single-phase and three-phase EV installs.