quick one

[domestic spark]

if in the intake to a building, its tn-cs pme three phase, then from that you have meters and to each flat you have 2 core armoured, and earth off the shiefing, is this a tn-cs system at the orign of the flat cheers!

 

[Mark.W]

No you could determine your min cpc size by using the adibiatic equation.

 

[domestic spark]

only bought this topic up as i am not currently NICEIC etc. someone i know had a peroidic done on a property i looked at it and spotted supply system type TN-S. but its TN-CS PME at intake downstairs, this is obv incorrect. was just confirming it with everyone, NICEIC ayy? i thought to myself so at what point did the supply change to a TN-S on route to the property haha!! also ZE was 0.26ohms.

 

[domestic spark]

how was this overlooked?

 

[Mark.W]

That's the thing, it's still a PME. You can use the armour as the cpc and as telelectix stated you just need to be sure that the armour can safely carry the fault current.

I see what you're saying the PIR should have picked that up!