16mm or 6mm

[Buzz-light-bulb]

Hi all

Im currently on with a condition report and it's a tn-s earthing arrangement with a 6mm coming off the sheath into an earthing block then a 16mm from there to the cu, now would you put 6mm as main earthing conductor as this is worse case or 16mm as it goes into the board. Or shall I put my tin hat on

 

[Buzz-light-bulb]

The 6mm is a cable and forms part of the main earthing conductor, the fact that it is 'sweated on' by whoever, makes no difference - it is the smallest cable so imo should be recorded in the form.

Ze values etc have nothing to do with just recording the physical size of a cable - I agree you can write what you want on the form regarding whether it is an issue or not.

You do have a fairly good point

 

[ChrisElectrical88]

He does, but who is going to bite the bullet and phone their scam?

 

[sparky6078]

The earth is on the EB supply is it not? shouldn't it be noted in services cables on the tick sheet? or am misunderstanding, the consumers main earth bond is 16mm is it not.

 

[Octopus]

The 6mm is a cable and forms part of the main earthing conductor, the fact that it is 'sweated on' by whoever, makes no difference - it is the smallest cable so imo should be recorded in the form.

Ze values etc have nothing to do with just recording the physical size of a cable - I agree you can write what you want on the form regarding whether it is an issue or not.

So you record the 6mm and thus a C2 - are you happy? As far as I'm concerned its 16mm and A OK.

I use PIRform and if I record the 6mm it will highlight a C2.

I may even call Elecsa later and see what they say!

 

[AndyL]

This is a TN-S system, where does it say it must be 16mm earthing conductor?

 

[Hawkmoon]

The earth is on the EB supply is it not? shouldn't it be noted in services cables on the tick sheet? or am misunderstanding, the consumers main earth bond is 16mm is it not.

So are the CU tails

Back in the day (i'm old) you would probably have found this 6mm connected direct into the CU - It was considered the main earthing conductor then! So extending it with a bit of 16mm now does not change that and imo it can't be ignored.



Not saying there is necessarily an issue with it, just saying the 6mm should be recorded as main earth size.

 

[Hawkmoon]

So you record the 6mm and thus a C2 - are you happy? As far as I'm concerned its 16mm and A OK.

I use PIRform and if I record the 6mm it will highlight a C2.

I may even call Elecsa later and see what they say!

The code (if any) that you apply to it is your decision, not PIRform's (is it not editable?)

When you assess the main earthing conductor you consider its full length not just your shiny new 16mm bit!

 

[Richard Burns]

On one of my assessments I listed the earthing conductor (that is defined as the cable from the means of earthing to the MET) as 10 mm as this is what came from the sheath to the (external to CU) MET. I got told to change this to the 16mm that ran from the MET to the CU.

Therefore from now on I assume that the DNOs side of the earthing of installation is not covered by my inspection and that the cables I can change are those for the main earthing conductor.

 

[D Skelton]

This is a TN-S system, where does it say it must be 16mm earthing conductor?

FINALLY! Someone with some sense! 6mm ME C2 on a TN-S?!?!?! Do me a favour!

As someone has quite rightly pointed out, the main earthing conductor is what connects the installation to the suppliers earthing facility or the earth electrode. If the suppliers earthing facility is a 0.5mm piece of flex but the conductor connecting this to the installation is 16mm then 16mm is the size of the MEC.

Even so, what if the main earthing conductor was 6mm? Confirm the size is adequate using an adiabatic equation and away you go!

 

[Hawkmoon]

FINALLY! Someone with some sense! 6mm ME C2 on a TN-S?!?!?! Do me a favour!

As someone has quite rightly pointed out, the main earthing conductor is what connects the installation to the suppliers earthing facility or the earth electrode. If the suppliers earthing facility is a 0.5mm piece of flex but the conductor connecting this to the installation is 16mm then 16mm is the size of the MEC.

Even so, what if the main earthing conductor was 6mm? Confirm the size is adequate using an adiabatic equation and away you go!

The point is does this mean the 6mm cable or does it mean the what the cable is attached to (the sweated joint) - as I have said originally this 6mm will likely have been directly connected to CU and was considered MEC then, throughout its length.

I have not argued that there is a problem with the 6mm (although this has been repeatedly assumed throughout the thread), I have only argued what size should be entered in the report.

 

[Buzz-light-bulb]

Suppose the 6mm is down to the dno as we cannot tamper with it, next will be noting down csa of suppliers sheath

 

[Hawkmoon]

Suppose the 6mm is down to the dno as we cannot tamper with it, next will be noting down csa of suppliers sheath

You can't tamper with your own consumer unit tails where they enter the meter either...(unless the seal has disappeared of course lol)

Imagine you had 3 CUs wired from the MET and this 6mm running from MET to sweated joint - would you still not consider it at least a part of the main earthing conductor?
Doesn't matter who owns it, who sweated it in, etc

What if the MET is in the CU? We can then still ignore the 6mm coming from sweated joint to CU???

 

[Buzz-light-bulb]

Just spoke to Niceic helpline 6mm would have to be noted as this is part of the main earth and it has a smaller csa

 

[Buzz-light-bulb]

6mm it is

 

[Hawkmoon]

Just spoke to Niceic helpline 6mm would have to be noted as this is part of the main earth and it has a smaller csa

Nice post!! lol - seriously though if you ring them on another day you are just as likely to get a different answer as R. Burns post.