Recently sat the 18th Edition Course and of the understanding EV Charging points shall be fed from a TT Supply. PME is acceptable only when feeding any other equipment ie Lamp posts Ticket Machines for example and providing Type A or Type B RCD is fitted and the Charger point is then to be separately spiked. Just looking on the attached and a company called Pod Point suggest TN-S is acceptable with no need for an earth spike. Wondered if anyone else has come across this diagram and can confirm TN-S is acceptable without the spike (see - page 2)
The prohibition/limitation on using the supplier's earth is only for PME systems - so TN-S (even perhaps PNB) is fine according to the regs.
The trouble is that unless you've got your own private transformer (or generator) you can't be sure that you've really got a true TN-S supply - the DNOs have been happily combining N and PE whenever they modify existing networks or replace cables so what appears to be TN-S at the cutout (e.g. earthing conductor connected just to the cable sheath) might really be PME once under the pavement - and so is subject to the same risks from broken CNE conductors and so on. So most people make the assumption that a DNO provided LV supply, unless specifically guaranteed, the earth terminal should be treated as PME.
The prohibition/limitation on using the supplier's earth is only for PME systems - so TN-S (even perhaps PNB) is fine according to the regs.
The trouble is that unless you've got your own private transformer (or generator) you can't be sure that you've really got a true TN-S supply - the DNOs have been happily combining N and PE whenever they modify existing networks or replace cables so what appears to be TN-S at the cutout (e.g. earthing conductor connected just to the cable sheath) might really be PME once under the pavement - and so is subject to the same risks from broken CNE conductors and so on. So most people make the assumption that a DNO provided LV supply, unless specifically guaranteed, the earth terminal should be treated as PME.
