UK Exceeding the max Ze in this situation still be considered to comply?

[Weezy]

If the max Ze for Tncs is 0.35 but you had a 1361 60amp fused isolator before the c.u with the 1361 having a max Zs of 0.56 (from the 80% chart) if the recorded reading at the c.u was let’s say 0.47 ohms would that now be considered to comply? i can’t see why it wouldn’t.

 

[pc1966]

So is the fused isolator feeding some long tails/sub-main to the CU?

If the Zs at the end of the sub-main (i.e. at the CU) is measuring below 0.53 ohms (from my OSG Table B5) then everything is fine, assuming the earth/CPC is at least 10mm to meet adiabatic limit.

If it is some old installation with a 6mm CPC then the Zs limit is 0.47 ohms to meet adiabatic (see Table B5) but really in that case you ought to be looking to replace it with 16mm to meet other regs.

 

[Weezy]

So is the fused isolator feeding some long tails/sub-main to the CU?

If the Zs at the end of the sub-main (i.e. at the CU) is measuring below 0.53 ohms (from my OSG Table B5) then everything is fine, assuming the earth/CPC is at least 10mm to meet adiabatic limit.

If it is some old installation with a 6mm CPC then the Zs limit is 0.47 ohms to meet adiabatic (see Table B5) but really in that case you ought to be looking to replace it with 16mm to meet other regs.

Yea that’s right and it is 16mm.
I’ll check that table myself, thanks for verifying though!