Earth for gas meter question

[PrenticeBoyofDerry]

But in earlier posts all the contributors to this thread including yourself are assuming that plastic gas mains can enter buildings, they do not and never hane done.

I don't recall stating that, the only time I have mentioned internal plastic pipes were in reference to a specific requirement not necessarily gas, so you may have misunderstood. The topic is concerning insulated services pipes within the meter cabinet on the supply side.

 

[GaryMo]

The OP's situation, as I understand it is he's had a new gas main from the road to his external meter cabinet, from the meter is copper, including the section entering the property.
If a resistance measurement was taken from the MET to the copper pipe entering the property I can see it being higher than 23Kohms and therefore not extraneous by definition.

 

[donrkebab]

But in earlier posts all the contributors to this thread including yourself are assuming that plastic gas mains can enter buildings, they do not and never hane done.

I don't recall stating that, the only time I have mentioned internal plastic pipes were in reference to a specific requirement not necessarily gas, so you may have misunderstood. The topic is concerning insulated services pipes within the meter cabinet on the supply side.

Yes, quite right, I missed the bit about the external meter.

 

[GaryMo]

Same stands for a plastic water pipe entering a property with a resistance between the copper side and the MET being over 23Kohms.

In reality though, most will bond, rightly or wrongly and that way there will be no come back. Still, it's worth a debate.

 

[PrenticeBoyofDerry]

Yes worth a debate indeed, though I don't disagree with your reasoning.
My input was purely in regards to the requirements of BS7671 and if bonding were omitted, which requirement would satisfy this as far documentation/certification. Taking in to consideration chapter 54 does state the need to bond after insulated services.

 

[GaryMo]

My input was purely in regards to the requirements of BS7671 and if bonding were omitted, which requirement would satisfy this as far documentation/certification.

OK, you take 544.1.2 to definitively mean that under all circumstances a protective bonding conductor should be installed to incoming services.

Do you also accept that protective equipotential bonding is solely in place to ensure all incoming extraneous conductive material is at the same potential as the properties main earth?

If so, would you accept that a resistance of over 23Kohms between the MET and any incoming service deems that it isn't extraneous?

If you're still with me on this then a deviation on the EIC (120.3) stating that after measuring the resistance between the incoming gas service pipework and the MET, the result of which was over 23Kohms (less than 10mA) it's deemed that the service pipework isn't extraneous and can't introduce a potential from outside of the equipotential zone therefore a protective bonding conductor would not be necessary in line with 544.1.2.

 

[PrenticeBoyofDerry]

I accept what your saying in regards to threshold of perception and let go values.
Call me old fashioned or in need of rectum protection. I would still bond, even if I was happy that the values measured allowed me not to.
But I do appreciate your input and you have enlightened my views and thoughts on this process.

 

[EFLImpudence]

If so, would you accept that a resistance of over 23Kohms between the MET and any incoming service deems that it isn't extraneous?

I would accept that as well. It is correct.

However, (whilst not knowing why the regulations state that it should still be main bonded) I would point out that, without disconnecting the gas supply from the boiler and any supplementary bonding (and ensure it is not touching any other pipework), it would not be possible to determine a value of 23kΩ and, when connected to the boiler it will be bonded by the water service (and Central Heating if bonded) and, indeed, earthed by the boiler cpc.

Also, I would agree that any bonding necessary at the point of entry, especially if the water is close-by (as in this thread), could be satisfied by supplementary, rather than main to the MET.

Can we discover why the regulations state that main bonding is still required?

 

[GaryMo]

Can we discover why the regulations state that main bonding is still required?

Really not sure. I don't have a copy of GN8 (Earthing and Bonding) but I do wonder if that could shed any light?