"The existing consumer unit has no spare ways, what are my options?"

A combined PEN fault + RCBO + surge unit fitted as its own small enclosure next to the existing consumer unit is usually the simplest route, rather than trying to shoehorn separate components into a full board. See PME protection devices for the combined options.

"Customer wants solar added later, does that change the PME protection now?"

Not directly, the PME/PEN fault protection for the EV charging circuit is unaffected by a future solar install on a different circuit. It's still worth flagging to the customer that the solar inverter circuit will need its own AC-side surge protection assessment when it's fitted. See do I need surge protection? for that separate assessment.

"Supply looks like PME but the customer says they have an earth rod already, what's going on?"

Some properties have a supplementary earth electrode fitted for other reasons (older installations, specific equipment requirements) while still being on a PME supply overall for the main earthing system. Don't assume the presence of a rod means the installation is TT; verify what it's actually bonded to and for what purpose before relying on it for the EV circuit.

"Can I use a 30mA RCD reading as evidence the PEN fault protection is working?"

No. An RCD trip test confirms the RCD is working, it says nothing about the PEN fault detection function, which is a separate monitoring system entirely. Test the PEN fault function specifically, using the device's own test method. See the main PME guide for the full comparison of what each protective device actually checks.

"Job's on a shared private supply serving several houses, does that change anything?"

Shared private supplies can have non-standard earthing arrangements, so verify the actual earthing system at the point of connection rather than assuming it matches the public network's usual pattern for the area. If in doubt, a specific supply test or a conversation with whoever manages the private network is worth the time before specifying protection.

Frequently asked questions

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