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

[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.