Andy Wade wrote:

Since this was publicised by the IEE

Any reference to when and where "this was publicised by the IEE" and
quasi-officially recommended? ICBW but I don't think the NICEIC
technical manual mandates it if the mounting box is not touchable.

I *think* I'm remembering a section in one of Trevor Marks' bookses. But
old age being what it is, ...

Stefek