When installing EV chargers in the UK, one of the biggest compliance challenges is the earthing arrangement. Most domestic supplies use PME (Protective Multiple Earthing), which poses risks if the neutral is lost. Since the 18th Edition Amendment 2, every EV charger install must have a compliant PEN fault detection solution. This guide breaks down what PME compliance means, how to achieve it, and which products help you pass inspection the first time.

🧭 Jump to:

• Why PME Compliance Matters
• 18th Edition Rules for EV Installs
• How PME Fault Detection Works
• Approved Methods of Compliance
• Recommended PME Fault Detection Units
• FAQs

Why PME Compliance Matters

PME supplies are common across the UK, but they come with a hidden risk: if the neutral fails, exposed parts can become live. For EV chargers installed outdoors, that risk is multiplied — making compliance critical, not optional.

• PME combines neutral and earth; a lost neutral can raise touch voltages to dangerous levels.
• EV chargers are classed as outdoor equipment, increasing shock risk on PME.
• Non-compliance risks failed DNO approval and costly call-backs.

18th Edition Rules for EV Installs

The latest wiring regulations (BS 7671:2018 + A2:2022) require protection against open PEN faults for EV charge points on PME supplies.

• Open PEN protection is mandatory on PME-fed EV chargers.
• Earth rods were once the default but are often impractical on modern sites.
• PEN fault detection devices are an allowed, inspection-ready alternative.

How PME Fault Detection Works

PEN fault detection devices continuously monitor the supply. If dangerous voltages are detected due to a neutral issue, they disconnect the EV circuit immediately.

• Monitors line/neutral/earth conditions for lost-neutral events.
• Trips a contactor/RCBO to isolate the charger when thresholds are exceeded.
• Many units integrate load balancing and SPD to save space.

Approved Methods of Compliance

Both options below can comply; site conditions usually decide which is best.

• Earth electrode (rod): Traditional solution; performance depends on soil/resistance and location.
• Standalone PEN fault detection devices installed alongside the board.
• Consumer units with integrated PEN protection (fastest fit, fewer terminations).

Recommended PME Fault Detection Units

Install-ready options, proven on domestic and light-commercial EV jobs:

• IP65 PME Fault Detection Unit with Load Balancing Relay
• PME Loss Consumer Unit with 40C RCBO + Surge Protection

FAQs

Do all EV charger installs need PME protection?

Yes. On a PME (TN-C-S) supply, EV charge points must include open PEN protection to meet the 18th Edition.

Can I still use an earth rod?

Yes, provided site conditions allow a reliable earth. Many installers now prefer detection devices for a faster, cleaner fit.

What’s the difference between standalone units and PME consumer boards?

Standalone units add PEN detection alongside an existing board. PME consumer boards integrate PEN detection with RCBO/RCD and often SPD, saving space and install time.

Will these units pass DNO inspection?

Yes — our PME units are built to 18th Edition requirements and are used nationwide on approved installs. Always submit accurate schematics with your notification.

👉 Compare our full range of PME Fault Detection Boards and Units