Main Earthing sizes for PME?

[tom91]

I'm about to have my TT installation upgraded to PME. At present we have a 10mm gas bond, 6mm water bond and 6mm from CU to earth rod.

From what I've read here, I'll fit a new MET on the meter board, run 16mm G&Y to the CU and install a new 10mm water bond.

It seems that some DNOs require a greater earth size. I tried ringing the number on the confirmation letter Eon sent (their 'asset alterations team') but the girl on the other end didn't even realise that gas water have to be earthed. Do Eon have some sort of tech department? Or is it a reasonably safe bet that 16mm and 10mm will be fine?

My other question is about the 10mm gas bond. At present, it runs to the earth terminal in the CU. When I have installed a MET, will I need to extend the gas to this, or just leave it in the CU?

Thanks for any help.

 

[Albert]

16mm and 10mm will be fine.
All main earth and bonding have to be linked, you can connect them all in the CU or in a main earth block but make sure that this block is connected to the CU (16mm).

 

[ericmark]

Albert is spot on and the earth rod becomes an "extraneous-conductive-part" and does not need to be removed it is classed like the gas and water pipes.
I did once check the cross sectional area of a 20mm copper pipe and it works out at about 16mm sq so under fault conditions one would not want the gas pipe to be weakest link hence use of 10mm cable being the norm.