95mm 4core SWA, just trying to go definitive on the steel to copper calculation

[bigspark17]

A 50mm earth should be pulled in alongside the swa. Alternatively If the water as stated above is the only extraneous part that needs bonding why not remove the metal pipes and install plastic. Are you sure theres no other parts that need bonding, structure or gas?

 

[andysparkfree]

unfortunately there is 6 w.c units, 3 shower units and 3 kitchens all done in copper
so ive had various conversations with the design company (not that they say there wrong as such) but the regs say 50mm separate earth so thats what is going to be ordered
now an interesting question i have regarding the pme separate earth and possible long/ high currents within the earth if there is a fault on the neutral , is that in the main panel that has the 300mm feed tails , it goes into a 300ma rcd pri to feeding any outputs like the building that has the 95mm feeding

has that any relevance in this whole saga ??

thanks guys

knowledge is power and all that

 

[Leesparkykent]

Not unless the far end was made TT.

 

[westward10]

I don't see the benefits of a 300ma rcd on a TN system, what type of site is it.

 

[andysparkfree]

very strange site to be honest , theres the main offices we have just done , followed by an asbestos lab building then 2 x vehicle garages for there vehicles then a massive stores building and a scrap/ recycling plant at the far end with a few portacabin type units for something or other

 

[andysparkfree]

only our building is fed off the new panel so far , the others will follow

 

[johnduffell]

unfortunately there is 6 w.c units, 3 shower units and 3 kitchens all done in copper

I know I'm a month late but you only need to insert an insulating section between the extraneous part and the part in the equipotential zone. Even a foot of speed fit pipe would be ample.
As long as it doesn't become extraneous elsewhere, it should test out fine once isolated from ground.
Having said that, I'm surprised a new building doesn't have blue mdpe incoming water.