I see no reason to prohibit feeding the chargers from the houses, and this may be cheaper than paying for another DNO supply.

Presuming that the chargers will be near each other, I would bond them to each other.

Thanks broadgage.

I couldn't think of a technical reason why it couldn't be done. With having never done it this way previously, it just feels a bit odd having not done it that way before. 

broadgage said:

I would bond them to each other.

BS 7671 requires simultaneously-accessible exposed-conductive-parts to be connected to the same earthing arrangement. Which leads you to providing a TT earthing arrangement at the charging points, because you can't just bond stuff together from different installations (could cause some nutty problems with PME at least).

If they share the same TT earthing arrangement because they are under the control of different installations owners, this could present a number of difficulties in future.

Who owns the charging points? Who will own the common TT earthing arrangement, and maintain it? Optionally - could provide separate earth electrode for each charging point ... but then, who owns the bonding connecting two different owner's charging points, and who is responsible for maintaining that?

because you can't just bond stuff together from different installations (could cause some nutty problems with PME at least).

Although we've been interconnecting different PME installations for years - e.g. by bonding shared metallic water pipes in terraced houses - and the results haven't always been disastrous. But certainly not ideal, I'd agree.  Also the other charge points would in effect be extraneous-conductive-parts as far as each installation was concerned (they'd certainly be vulnerable to carrying diverted N currents), so you'd be looking at PME sided bonding conductors for each charge point's c.p.c. - which might not be attractive ether.

   - Andy.

Before panicking, does each house present as having a TNC-s earthing system - and if it does, as above, they may be better supplied as TT  (SWA with PME proteciton of the armour, but stopping there) If the houses are fed from different substations then it could get quite messy.

Generally inspection and maintenance will need to be agreed, maybe even in the deeds anyway, as would supplies from many houses out to a cluster of garages, or any other shared facility, though that is a more common situation, or indeed who cuts the grass around the things.

You may need to organize the chargers as a number of distinct islands.

Mike.

mapj1 said:

islands

I suggest this perhaps means separated TT earthing arrangements (meaning no simultaneously-accessible exposed-conductive-parts between installations, and also suitably separated below ground as per IET CoP for EV Charging? But that's not an 'island'.

This is an electrical island: www.electropedia.org/.../display, i.e. based connection to power sources, not connection of earthing arrangements.