PME, also called TN-C-S, is the earthing system on most UK homes. The neutral and earth are combined in the network and separated at your cut-out. It is a sound system for the house and a known problem for a metal vehicle parked outside: if the combined conductor is broken in the street, the car body can become live. That is the open-PEN fault. Charger designs deal with it by detection and disconnection, or by a different earthing arrangement such as a TT island where that is appropriate.
Handover when pME earthing explained for EV chargers is the issue
The certificate should describe the earthing system and the protective measure. Keep that page.
PME earthing explained for EV chargers
You do not choose PME. The network does. Your job is to hire someone who identifies it and designs the charger circuit accordingly. A charger indoors in a way that never connects to a car outside is a different risk picture from a wallbox on a drive, but the usual home case is the outdoor one.
- PME is the common UK domestic system
- Open-PEN is the outdoor-vehicle risk
- Detection or an alternative earth are design answers
- A random earth rod is not a DIY upgrade
What a survey must prove about pME earthing explained for EV chargers
Ask the survey to state PME, TN-S or TT. If the installer cannot tell, they have not finished the survey.
PME earthing explained for EV chargers and the written scope
The protective method should be in the price of a mainstream UK charger. Unusual earthing conversions should be explained, not hidden in a vague 'electrical works' line.
The expensive shortcut on pME earthing explained for EV chargers
The mistake is driving an earth rod because a video said 'never trust PME', without testing and without a design. A random rod can be worse than the arrangement you removed.
Frequently asked questions
Is TN-S safer for a charger?
It avoids the combined neutral and earth in the street, so the design differs. Many homes that think they are TN-S have been converted to PME. The survey has to look.
Does a plastic charger body solve it?
No. The car is metal and the lead connects to it.
Are flats different?
The supply system still matters, and the landlord's installation may add rules. The physics of PME does not stop at a flat.
Can I see PME at the cut-out?
Sometimes the label says so. Sometimes only the records and the installer inspection will. Do not pull the cut-out.
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How this guide was prepared
This guide was written by the Local EV Installers Editorial Team. We compare official guidance, legislation and established consumer information, separate general information from project-specific advice, and show publication dates and sources. We do not accept installer accreditation claims at face value.