6mm Main Earthing Conductor

[deejay]

I'm looking at doing a CU change. Current main earthing and bonding conductors are both 6mm. Tails are 16mm on a 60/80 amp fuse (TNCS). ZE = 0.1 , 230v, single cable not bunched.

Looking at the regs (543.1.1) and applying the adiabatic equation (543.1.3), 6mm seems ok for main earthing conductor.

As for bonding, BPG1 states that 6mm will be ok if there is no sign of thermal damage.

It would be quite a job to replace so hoping not to.

Am I missing something glaringly obvious please? Thanks

 

[westward10]

Pre 16th Ed (15th Ed) the Regulations never quoted a minimum size for main protective bonding for TN-C-S supplies they suggested consulting the supply company, so with this in mind and assuming this is pre 16th Ed you will never know whether those conductors fulfilled the requirements of the time.

 

[DefyG]

Confirming Note 5 of BPG as per post #2 will confirm or otherwise.

 

[Lister1987]

The first port of call for me would be to verify with DNO that 6mm would meet requirements for a supply from them, then I'd look at 7671.