On 18/06/2019 09:13, Martin Brown wrote:

Arising from the EV Charging in the UK thread I am having an argument
with a USian who insists that UK wiring is unsafe and uses a combined
protective earth and neutral to save money aka PEN and TN-C-S. This
seems to be permitted in BS 7671 although I have never seen it myself.

https://en.wikipedia.org/wiki/Earthi...of_TN_networks

All the installations I have ever seen are either rural TT or old build
TN-S where the sheath of the incoming armoured cable is a true earth.

So how common is TN-C-S with a single PEN in new build? What proportion
of homes in the UK have the potential for every metallic "earth" bonded
surface in them to be made live if the neutral return were to fail?
(It only requires one appliance to be on for this to happen)

The best description of it I have found so far is he

https://professional-electrician.com...earthings-pme/


So it seems some UK households do have this configuration.


AFAIK PME has been the /default/ for new, ordinary connections for quite
some time. (By 'ordinary' I mean not a caravan, boat, railway etc.)
And a fair few older houses which started out as TN-S have been switched
to PME.


--
Robin
reply-to address is (intended to be) valid