18th Edition changes regarding sub-mains

[AndyPRK]

Rather pointless if they are located next to each other.

Nicc disagree

 

[Risteard]

Rather pointless if they are located next to each other.

Nicc disagree

It's not pointless at all - it provides protection against making all earth metalwork in the installation live with a fault before the RCD protection in the DB. My NICEIC Area Engineer liked the way I had done it on the last TT system visited during periodic surveillance visit.

 

[JohnW2]

No it wouldn't because I would always house it in an insulated enclosure.

I don't see what difference that makes (other than that that insulated enclosure would not 'become live', even if all the exposed-c-p's in the installation did - after all, the cables ('tails') which you fear could result in "all earthed metalwork in the installation [becoming] live" have two ends, one of which will enter the CU (which, if compliant with current regs, will almost certainly be metal).

Kind Regards, John

 

[Risteard]

I don't see what difference that makes (other than that that insulated enclosure would not 'become live', even if all the exposed-c-p's in the installation did - after all, the cables ('tails') which you fear could result in "all earthed metalwork in the installation [becoming] live" have two ends, one of which will enter the CU (which, if compliant with current regs, will almost certainly be metal).

Kind Regards, John

Those cables are protected by the RCD though, unlike any supply conductors to it. However with an insulated enclosure this risk is addressed.

 

[JohnW2]

Those cables are protected by the RCD though, unlike any supply conductors to it.

Fair enough - but, as I said before, I think you are talking about a very unlikely fault (assuming the installation is done competently).

Kind Regards, John