wrote:

My house supply is TN-C-S but also has an earth rod. It's a dedicated
supply that runs overhead for some distance before diving underground to
get into the house. An earth rod with PME seems to be controversial but
I can't see any downside for an isolated property.
Have I missed anything?

The outside connection to the earth rod should be mechanically protected
and insulated from being touched. It should have decent size of wire
connecting it directly ot the main earth terminal by the incoming main
fuse. There shouldn't be any additional connections to it except via
the house wiring. Then I can't see what harm it could do (others
might!) but don't rely on it to alter the characteristics of the TN-C-S
installation.

--

Roger Hayter