A TN-C-S system uses a combined protective and neutral (PEN) conductor in the distribution network, earthed at many points, and splits it into separate neutral and protective earth conductors at the service position. It is the most widespread arrangement for new urban supplies in the UK, Australia and North America. Its weak point is a broken PEN: if the combined conductor opens, installation metalwork can rise toward line voltage, so rules restrict its use for EV chargers, caravans and outdoor metal.
It's a TN-C-S supply, so the EV charger needs open-PEN protection or its own earth rod before we connect it.
UK electricians call it PME, Australians MEN (multiple earthed neutral); the arrangement is the same.
Also heard as
- PME
- protective multiple earthing
- MEN
Related terms
PEN conductor
Single conductor that serves as both the neutral and the protective earth in a TN-C network.
TN system
Earthing arrangement where the source is earthed and installation metalwork connects back to it by a protective conductor.
Earthing system
Arrangement describing how a supply's neutral and an installation's exposed metalwork are connected to earth.
Equipotential bonding
Connecting metal parts together so they sit at one potential and no dangerous voltage appears between them.