Running PME (TNCS) outdoors?

[TheFullHitSpark]

Alright guys, ime racking my brains and books trying to find out why my boss told me that you are not supposed to run PME outdoors to say out feeding a garage or a shed of some sort, i know about potential differences.... also i know some about special locations but i just cant understand why your not allowed PME, surely if the cable is protected by an RCD, the same as it would be if you was using an earth steak for TT what is the difference?? can someone elaberate on this for me please. if this is the case you would have to have an earth steak which would be a seperate means of earthing than provided from your source, but obvioulsly your (PME) earth would still have to provide protection for the cable feeding the (sub main).

Thinking outloud abit..



If someone could show me the light i would be mostly appreciative.




Cheers guys, also as you all probably know this forum is the dogs go-nads...

 

[IQ Electrical]

Does a PEN conductor form part of a PME?

Yes, up to the service head where it ceases to exist (it is separated).

That is the 'S' in TN-C-S

 

[gamblor6]

all threads on this subject roll merrily along until, i can tell, you.ve had enough

 

[SimpleSimon]

Yes, up to the service head where it ceases to exist (it is separated).

That is the 'S' in TN-C-S

I know. But I now know what I wad confusing the reg earlier with. As always IQ, thanks for your help

 

[pushrod]

The impression I get is that the presence of extraneous conductive parts does not preclude the use of an exported TNC-S earth, it mearly means that they have to be bonded back to the submain MET with the same size cable as is appropiate for doing the same in the main building, and that the same sized or bigger earthing cable is used to provide the earth to the submain board, and as this is not always practical, a way of avoiding having to install bigger cables is to convert the remote installation to TT, and bond extraneous bits back to this

I think!!!!!!

pretty much what i think too -and once you get to about 12M of 10mm bonding it gets cheaper to to put an earth electrode in unless there is some other complicating problem.

 

[Deleted member 9648]

Bang on.....but most of these threads are about sheds and garages with no extraneous conductive parts requiring main bonding.