Not really sure thats correct? Sometimes you need to go up a cable size to meet Zs requirements, depending on the characteristics of the protective device...
Gets particularly tricky with big Type C and D breakers.
The supply is currently TN-S. But its some nasty 6mm VIR cables in a conduit from next door, with the earth supplied by the conduit and a clamp.
I had the DNO out to look at it not long after moving in, and the guy agreed it was bad and needed replaced, but said it was a low priority job...
Marvo: I could probably get some bootlace ferrules and crimper from work, if that would improve the termination issues?
Andy: Thanks. I'd hate to install it with the 4mm earth and find the Zs is above whats allowed for the Fuse protecting the submain. Theres also potential equipotential zone...
I'm about to replace the cable that feeds a small workshop/big shed in my garden.
Currently there is 2.5mm T&E from the CU, thru the house, out thru the wall and off along the ground completely unprotected before going up the wall and entering into the workshop. To top it off, its protected...