That's really interesting. I can't say I'm familiar with such requirements in other areas, but it probably has to do with safety regulations and electrical safety requirements. If the grounding in your home is not up to standard, it can lead to a variety of problems, including the risk of electrocution. NI may believe that connecting to a household installation without a basic safety connection can be hazardous to life and limb and therefore requires compliance with appropriate regulations and requirements.

It wasn't so long ago that we, in England, were doing sort of the same thing - installing bonding to the copper pipework internal to the property, when there was a plastic incomming service - I don't think anyone ever cut the plastic pipe to insert a copper bit? Certainly all the way through the naughties the bonding had to be in no matter what.... hence why we saw silly plasic pipes bonded. (For new or restored supplies from the suppliers.)

Its only rather recently that we are specifically allowed to leave the bonding out if the incomer for the gas and water is in plastic. I've not dealt with the suppliers and new connections on a property with no bonding; I assume they'll connect up now with no bonding in place? 

I've not done domestic though for a decade or so may be behind the times and "not so long ago" might mean more than 10 years ago. 

Never assume those in charge know what they are talking about.

I do wonder sometimes! That said, what about the argument that to leave the internal metallic pipework unearthed, what would happen if it became live? Conversely, to bond the internal pipework would be to potentially introduce a dangerous supply of energy to a previously isolated piece of exposed metalwork.........

That said, what about the argument that to leave the internal metallic pipework unearthed

In the vast majority of cases the internal gas pipework will still be earthed via the boiler or hob (igniter) c.p.c. - so omitting main bonding usually makes no difference on that score.

   - Andy.

Sparkies have to fit a copper insert in the plastic pipe to install the bonding clamp.

I do wonder how they can insist on that, when the relevant standard (presumably BS 7671 still in NI) clearly says otherwise.

   - Andy.

They can insist on it by not connecting the supply until a bit of copper water pipe has been bonded.  You can sit and argue, and not get a supply. Or comply and be connected.

What BS7671 says isn't really relevant here.

What BS7671 says isn't really relevant here.

Doesn't NI have something similar to the ESQCR - which in effect says BS 7671 can be used as the yardstick for whether an installation may be connected or not, and go to the Secretary of State or even connect it yourself if the DNO are being unreasonable (Reg 25)?

   - Andy.

I did see a length (12") of copper pipe with a bonding connection inserted in a plastic water supply after a rewire in the UK, it had been very neatly done. All the water pipes in the house were plastic! so no negative consequences. I did take a photo but have not been able to find it since. There were a couple of other issues with the rewire including missing blanking plates in the CU. I have also been asked by a plumber to bond a gas pipe adjacent to the external meter supplied by plastic pipe, easier to do than to argue.

It's not a question of BS7671, ESQCR or any other "rules and regulations", it is physics.

You are all too polite while being held to ransom by idiots who do not understand. Are they equally incompetent with their own work?

Can you not explain to these fools that even if you needlessly insert a length of copper pipe into the plastic supply, that piece of pipe still does not require bonding.