TNCS 10mm existing Earth OK

[Richard Burns]

Quick question regarding Earthing conductor sizing.
I have just done a job on a TNCS supply with 16mm tails which has a 10mm earthing conductor, adiabatically this is OK and meets the requirements of 542 and 543 (but not 543.1.4).
However I had in mind that TNCS minimum earthing conductor size is 16mm, is this just from OSG (or as OSG says, a supplier requirement)?
i.e. is this install non compliant or complaint?

Thanks for your help.

 

[mickys86]

I was under the impression that the tails had to be 25mm and that the main earthing conductor had to be 16mm

Just the apprentice though. 

 

[Risteard]

Nothing wrong with using the adiabatic equation to size the earthing conductor. So if you've confirmed that it complies, then it does indeed comply.

 

[telectrix]

see table 54.7

 

[somersetsparks]

I think that it is a DNO requirement in some areas, however I think the requirement is for a minimum of 10mm2 anyways.
As has been said, regs wise, its fine.

 

[telectrix]

I think that it is a DNO requirement in some areas, however I think the requirement is for a minimum of 10mm2 anyways.
As has been said, regs wise, its fine.

table 54.7 , 16mm tails 16mm earth.

 

[telectrix]

I think that it is a DNO requirement in some areas, however I think the requirement is for a minimum of 10mm2 anyways.<br>
As has been said, regs wise, its fine.

should be OK by adiabatic calc. but generally on TNC-S , DNO insist on 16mm.

 

[Risteard]

table 54.7 , 16mm tails 16mm earth.

543.1.3

 

[telectrix]

and 544.1.1 and table 54.8 also point to 10mm where the neutral conductor is <=35mm.