What sockets

[bernardgreen]

I'm sure people will be tiring of my views, but I really think that, if one has any interest in safety, one has to think broadly and consider wet soil as an extraneous-conductive-part.

The regulations would appear to do that in some paragraphs. If they didn't then they would not require RCD protection for supplies to double insulated equipment used outside the house.

If the ground is "safe" and not an extraneous conductive part then it could not be the return path for fault current. If the ground does not introduce a path for current then RCD protection of a double insulated item of equipment could never work.

 

[JohnW2]

The regulations would appear to do that in some paragraphs. If they didn't then they would not require RCD protection for supplies to double insulated equipment used outside the house. If the ground is "safe" and not an extraneous conductive part then it could not be the return path for fault current. If the ground does not introduce a path for current then RCD protection of a double insulated item of equipment could never work.

Yes, I agree with all that. Indeed, I personally think it's a no-brainer - in terms of commonsense considerations of safety, and the word of the definition in BS7671, wet soil does constitute an 'extraneous conductive part'. Since it obviously cannot be 'bonded', one clearly has to take some other steps to avoid potential differences existing between it and any touchable conductors in the vicinity - and I personally think those 'steps' must inlude avoidance of any metal touchable by someone standing on the ground which is connected to a TN-C-S 'earth'.

... but all sorts of people (most of whom would probably regard the absence of MPB in an installation as being 'very dangerous') seem to disagree with me, so what do I know?!

Kind Regards, John.