TN-S earthing issue

[KevinH]

I have just carried out an EICR at an old property and found this issue with the main earthing conductor.
It has a TN-S system but the earthing conductor emerging from within the taped up tar coating just before the cut out is only 4mm2 of (what looks like) steel wire armourings. It is 100mm long connected to a small earthing bar. It is not the more popular lead sheathed with earth clamp moulded to it.
My question is, as there is no way to upgrade it without getting involved with DNO cable/equipment, should I just leave the 4mm earth and earthing block close to cut out, then upgrade all earthing from that point on.
Just to point out, at present there is only 4mm earth feeding a BS3036 consumer unit (due for replacement) with 6mm earthing to gas and water. The Ze reading is 0.17 ohms. Adiabatic calculates earth should be 6.19mm2.
Also, what codes for the DNO's undersized earth?

 

[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.

 

[cliffed]

we used to call that "passing the buck".

How come?

 

[UNG]

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

So if he failed to act on something you found to be a problem and an injury or fatality was subsequently found to be as a result of something you found would he be the one in court or you

It's the man on the ground that generally cops it as the guy further up the chain covers his back to avoid a stay at one of the HM Hotels around the country

 

[cliffed]

So if he failed to act on something you found to be a problem and an injury or fatality was subsequently found to be as a result of something you found would he be the one in court or you

It's the man on the ground that generally cops it as the guy further up the chain covers his back to avoid a stay at one of the HM Hotels around the country

What can you do, you’ve done a EICR,your PDH & QS signs the certification where appropriate,you’ve signed your bit.
You’ve noted the observation you may have coded it, then it’s there duty to do the necessary remedial’s,if required.
As an employee you are then asked to do the works,if those works are not assigned to you,that is not your problem.

 

[telectrix]

How come?

What can you do, you’ve done a EICR,your PDH & QS signs the certification where appropriate,you’ve signed your bit.
You’ve noted the observation you may have coded it, then it’s there duty to do the necessary remedial’s,if required.
As an employee you are then asked to do the works,if those works are not assigned to you,that is not your problem.

totally agree. yous done your bit. reported findings to the decision makers. it's then up to them to act.

 

[cliffed]

totally agree. yous done your bit. reported findings to the decision makers. it's then up to them to act.

Thank you?

 

[telectrix]

youse welcome.

 

[LastManOnline]

It is a requirement to check the suppliers earthing arrangement.

Yes. That was my thought. How do you guys confirm its still
TN-S?. If so 6mm is fine. But what if its been converted to TNC-S?

 

[Wilko]

If the means of earthing is still TNS at the cut out then that’s what I use. If the DNO placed PME stickers on the cut out then they would take precedence. But I’ve never seen this without the change to the means of earthing as well. Any new installation I do as if it will be/become PME.

 

[LastManOnline]

Any new installation I do as if it will be/become PME.

Agreed. Future proofing way to go.

 

[DefyG]

Adiabatic calculates earth should be 6.19mm2.

What figures did you use as I did one this past week with a much higher pfc (2.6kA) and k value of 159 (accessible to touch) for bare copper and works out smaller csa than yours.
You may have used the figure for steel but doubt the dno conductor would be steel, its probably tinned copper.

That aside its worthy of a note (C3 at worst), it meets the adiabatic requirements so all good. The consumers installation starts from the MET put in by the DNO so 16sq from that point! Bonding conductors may be terminated from there or the earth bar in the CU.