TN-S earthing issue

[KevinH]

The landlord has asked me to put right whatever it needs for a satisfactory cert so new DB goes without saying. New earthing from main earth block to DB as its currently less than 6mm. As I've gone this far, it makes sense to upgrade gas and water bonds as they are within same cupboard/area and easily enough to do although I could get away with leaving them as 6mm. Its just for my peace of mind that its done just out of good practice, and the landlord is happy to pay so why wouldn't I upgrade?

 

[Grant1987]

The landlord has asked me to put right whatever it needs for a satisfactory cert so new DB goes without saying. New earthing from main earth block to DB as its currently less than 6mm. As I've gone this far, it makes sense to upgrade gas and water bonds as they are within same cupboard/area and easily enough to do although I could get away with leaving them as 6mm. Its just for my peace of mind that its done just out of good practice, and the landlord is happy to pay so why wouldn't I upgrade?

I agree with you here I have two rules which I like to stick to. CSA of main earth should be at least half of supply conductors. Also within a TN earthing system should be minimum of 10mm. I do think a 6mm is undersized and needs upgrading just ring the DNO and speak to them I’ve done it many times and sub contracted work from them in my area after speaking to them

 

[cliffed]

Seen loads of these I always make a note on Eicr,Upgrade of Rec MEC required never know if it’s actually done.

 

[telectrix]

Seen loads of these I always make a note on Eicr,Upgrade of Rec MEC required never know if it’s actually done.

doubt if they ever do. that short bare bit of cable will handle fault current for the duration of the fault without melting or setting the house on fire.

 

[cliffed]

doubt if they ever do. that short bare bit of cable will handle fault current for the duration of the fault without melting or setting the house on fire.

Agree,can you imagine us doing that,NICEIC would have a heart attack.
He nearly had one when I asked about bonding.

 

[UNG]

Seen loads of these I always make a note on Eicr,Upgrade of Rec MEC required never know if it’s actually done.

So why not call the DNO when you are onsite if you have concerns about the earthing arrangement

 

[cliffed]

So why not call the DNO when you are onsite if you have concerns about the earthing arrangement

I give the report to my QS then hopefully he sorts.

 

[telectrix]

I give the report to my QS then hopefully he sorts.

we used to call that "passing the buck".

 

[Lucien Nunes]

I do think a 6mm is undersized and needs upgrading just ring the DNO

Why? (in the general case, acknowledging that there are situations where it is clearly true)

Do you have evidence of bare 7/.044 conductors failing to clear a 100A BS1361? Or does a larger conductor just 'feel' more suitable?

 

[telectrix]

the solder to the lead sheath would melt before that bare bit of 7/.044 overheated.