TNCS or TNS earthing arrangement?

Dunisan · Jun 29, 2023

Please can someone explain if this is a TNCS or a TNS earthing arrangement because it looks like both to me. Old undersized main bonding conductor goes into the neutral block first then to an earth block that's connected to the incoming cables sheath. My rather unhelpful supervisor told me to "figure it out for myself" today, I think someone was having a bad day...

If the consumer unit is getting swapped out would you run the replacement 16mm main bond to the Neutral block and 10mm supplementary bonding to the earth block on the side of the incomer shown below, gas and water so you would have 3 supplementary bonding cables?

Thanks

[ElectriciansForums.net] TNCS or TNS earthing arrangement?

rewireIT · Jun 29, 2023

I think you can ring the DNO to confirm.

westward10 · Jun 29, 2023

Was TN-S is now TN-C-S.

mainline · Jun 29, 2023

Dunisan said:
Please can someone explain if this is a TNCS or a TNS earthing arrangement because it looks like both to me. Old undersized main bonding conductor goes into the neutral block first then to an earth block that's connected to the incoming cables sheath. My rather unhelpful supervisor told me to "figure it out for myself" today, I think someone was having a bad day...

If the consumer unit is getting swapped out would you run the replacement 16mm main bond to the Neutral block and 10mm supplementary bonding to the earth block on the side of the incomer shown below, gas and water so you would have 3 supplementary bonding cables?

Thanks

View attachment 109121

Phone the Dno and ask them to upgrade.

westward10 · Jun 29, 2023

It was TN-S, it is possible earth continuity broke down and it was changed and the existing earth braid was connected into the earth terminal to earth the cable sheath, it doesn't need upgrading it isn't uncommon.