EICR earthing question

[KevinH]

Hi guys, This has probably been asked many times before but just want to know others opinions.
Just done an EICR and have found (or not found) any sign of a water bond near stopcock or anywhere in house.
There is an earthing block at the meter position with main earth from PME, an earth to DB, and another two 10mm earths going off somewhere, one would assume water and gas, (I know we can't assume as we have to confirm connection). I have excellent R2 continuity throughout all copper in the house. (No PVC fitted, all copper).
I have found however, the gas is 10mm and bonded in gas meter box. The only sign I can see of a water bond is that all copper pipes below boiler are cross bonded in 10mm hence bonding the water.
I'm assuming we cannot rely on this no matter how good the readings are and all bonded as it's not a continuous bonding cable to the water, but what code would you guys give this? I'm thinking C2 as it seems to be using the gas pipe to carry the earth to the water pipe (if that makes sense), but then in the trusty Napit Codebreakers I have found "Common main protective bonding conductor for installation not continuous" (section 3.7) and that gives a C3 code. Also "main bonding conductor not connected to point of entry of water/gas etc" which is also C3.
If I can get away with a C3 that would be great as the DB is at front door of terrace house and water incoming at rear in kitchen and the landlord wants a quote if it does need correcting.
Ideas?

 

[Julie.]

Does it need bonding?

You only require bonding if the associated pipe is an extraneous conductive part.

If it isn't, then it doesn't need a "full size" bond, and could be smaller as a supplementary bond, or as protective earthing.

 

[GBDamo]

To me its an issue of location of where the bonding is attached, not verifiable, and labelling as you've proved something exists. So I initially thought C3

As there are two 10mms, other than main earth, leaving the MET then it is a valid assumption to make, coupled with your testing, that one is water bonding.

Were your tests made with the gas bond removed?

My worry would be that water is cross bonding at the boiler so, if for some reason, the gas was removed then there would be no water bonding, a possibility?

The assumptions here make me feel a little uncomfortable with C3.

 

[KevinH]

In answer to your question, yes tests were done with gas bond removed. I even temporary removed earth to DB to hopefully eliminate any other possible paths (boiler supply etc) and still had good readings on water.
I'm a bit wary of giving a C3 as if the gas bond was removed for some reason, there's no guarantee there would be any bonding.
Can't get to the incoming pipe before stopcock to check if its PVC or whatever so can't guarantee it doesn't require bonding.

 

[telectrix]

C3 in my book.

 

[Wilko]

In answer to your question, yes tests were done with gas bond removed

Hi - for what it’s worth, I’ve found it can be hard to remove all connection from the gas service pipe to the MET. The boiler has its CPC connected to chassis (as it’s an external conductive part) and the copper gas pipe is solidly connected there. Then there’s the cooker, which has CPC to chassis and then either solid copper gas pipe, or even the flexible gas hose is conductive.

 

[loz2754]

If confirmed by measurement, and with all other bonding temporarily disconnected, then C3 with comment along the lines of "water bonding connection not verified, confirmed by measurement".

 

[KevinH]

Hi - for what it’s worth, I’ve found it can be hard to remove all connection from the gas service pipe to the MET. The boiler has its CPC connected to chassis (as it’s an external conductive part) and the copper gas pipe is solidly connected there. Then there’s the cooker, which has CPC to chassis and then either solid copper gas pipe, or even the flexible gas hose is conductive.

But surely if the earth to the DB was disconnected along with the gas bond, then that would disconnect the CPC's to boiler and cooker circuits? That's what I did and still had a very low ohm reading between the water pipe from the main earth block of around 0.04 ohms. That tells me the water pipe is earthed somewhere but it's just hidden and so can't confirm. I'm trying to convince myself it's a C3 to get out of an awkward job lol!

 

[Wilko]

But surely if the earth to the DB was disconnected along with the gas bond, then that would disconnect the CPC's to boiler and cooker circuits?

Agreed.
But if there is no other g/y evident, how is there 0.04 Ohms from the DNO means of earthing to your incoming water supply? I’m imagining you are measuring next door’s bonding, ha. It doesn’t happen round my way because all the incoming supplies are in plastic, so houses are isolated from each other excepting the DNO cable conductors.