On Mar 5, 3:21*pm, Graham. wrote:
OK confession time.
For a long time I had the neutral terminal of my room stat connected
to the CPC because there was no neutral. The CU didn't contain an RCD
at the time

SI 2002 #2665, ESQCR.
"A consumer shall not combine the neutral and protective functions in
a single conductor in his consumer's installation."

Reason being whilst the earth tests as dead, when you disconnect the
CU earth then every single (electrically) earthed object in the house
including gas & water pipes re MEB is now a floating live whose
ability to shock is only limited by the resistor (in this case).

So the next time John Prescott comes around... :-)