Gas bonding - which side of meter/valve

[James_H]

One electrician giving a quote picked up that my bonding is on the wrong side but no others did.

I know it should be on the customer's side but can anyone tell which side that would be from the arrangement in the picture? Both my pipe and the supply pipe come out of the solid floor so I cannot tell which is which.

In the picture, the tag attached to the clamp is just visible to the right of the meter. Should the clamp be on that side or below the valve?

Thanks.

 

[BJS_Spark]

The lever valve is the suppliers side and the customer side is on the right. So yes it is correct.
For reference the order is supplier-valve-regulator-meter-consumer

 

[yai46]

It is on the correct side located.

Looking at the picture the clamp looks ok but depending on the earth cable connecting to it, it needs to be 10mm!

 

[Spark123]

Looking at the picture the clamp looks ok but depending on the earth cable connecting to it, it needs to be 10mm!

I thought the size of main eq bonding depends on the type of supply and the DNO?

 

[James_H]

Thanks, always get good and quick replies here. The bonding isn't up to current standards and is going to be replaced by 10mm.

James

 

[Spark123]

What type of supply do you have?:
//www.diynot.com/forums/viewtopic.php?t=7553&postdays=0&postorder=asc&start=36

 

[James_H]

It's either TNS or possibly TNCS. It's the same as in the first and second diagrams but with the supply head too enclosed to tell without opening it up.

 

[Lectrician]

Judging by the size of the service cable, and the type of head (exposed earth block), I would say 75% TN-S.

You can use a loop impedace meter to find out.......See if the loop from the L to E is different from L to N.

 

[sparkybird]

I stand to be corrected, but that looks like a classic TNCS to me as otherwise the earth would be taken off the supply cable before the compnay head...

 

[Spark123]

It does look like TN-CS, to confirm this you can phone your Distribution Network Operator (DNO i.e. Norweb, Manweb etc) and they should be able to tell you. If it is TN-CS (also called PME) the DNO will need to tell you the size of cable to use for main equipotential bonding required. What size earth cable is connecting the DNO service head to the fuse box?

 

[Lectrician]

I stand to be corrected, but that looks like a classic TNCS to me as otherwise the earth would be taken off the supply cable before the compnay head...

The service cable looks slightly thicker than a 16mm concentric. I think it is a 16mm SPLIT concentric, having a seperate neutral and earth. We have many of these in my area. Very difficult to tell with out looking inside, or using a test meter.

Take a look at my earthing arrangement pics in the for-ref section.

It is very typical to assume a TN-S supply will have the earth connected to the sheath - many people think the S stands for SHEATH, it doesn't, it stands for SEPERATE (neutral and earth).

I too could be wrong, but in my area, the DNO will not use a head with exposed earth block if the service is PME.

 

[pdcelec]

It looks like TN-S to me, with the earth being taken from a concentric cable. If PME there should be a sticker stating it. Only sure method is to contact DNO.

 

[James_H]

Same 6mm size going to the consumer unit (and from there to the main water pipe) so this is being changed to 16mm and 10mm planned between the earth block and water pipe via the gas pipe.

I don't fancy phoning the DNO again. While searching in vain for an electrician round here able to self-notify that could be bothered to get out of bed for a £1000 small job, I contemplated doing the whole lot myself. Recommendations on here were to see if the DNO would fit an isolator to avoid having to pull the service fuse or work live. Their response was that my electrician can put one in! They said they only deal with the cables in the street and said to speak to Powergen, who I switched my bills to. After more passing the buck I gave up. DNO concerned is Seeboard, part of edf.

Of the sparks who did come to quote, no-one said anything other than 10mm for the main bonding.

 

[Spark123]

If the supply is TN-S, 10mm² is correct for the main eq bonding, the main earthing conductor (service head to CU) is now normally 16mm².