Is this method of earthing a water pipe permissible?

I am surprised that all those who understand bonding requirements are worried that someone later won't, and therefore want to carry on as before. If the alleged "Inspector" thinks that main bonding is always necessary, he is not qualified and that's the end of the problem. I am sick of people finding "defects" that are not defects at all, and then charging to "repair" them. This is simple fraud, and should be reported as such.

However an  “insulated” sections of pipe breaking the electrical continuity on extraneous pipework entering a building is no longer permissible if there lead, steel or copper coming out of the ground into a building it needs a Main Protective Bonding conductor, rather than just a few millimetres of plastic pipe and/or fittings before reverting to metal.

I don't think the CH pipes are in contact with the ground anywhere.

There are also the cold and hot water supply pipes around the house. They don't appear to be in contact with the ground anywhere.

I have a mentality that all (significant) sections of metallic pipework should be earthed and not left floating in case a pipe accidentally becomes live.

The CH pipes, along with the cold and hot water supply pipes (in the vicinity of the boiler at least), are earthed via the mains earth connection to the boiler. If the mains cable is disconnected then the pipes are most likely left floating.

I would be testing at 500 volts dc after temporary removal of the boiler cpc from the pipe work to the MET,this will prove whether its an extraneous-conductive-part or not . The value i use is 23 K ohms which would allow 10 ma . GN8 describes this process 

You need a surprisingly short insulating section to limit any currents to a level that is negligible (less than 10mA say) The rules for UK drinking water purity means that a foot or two of water  filled 15mm dia plastic pipe is  likely to be many 10s of k ohms if not exceeding 100k. Gas and oil are essentially insulators, It gets more complex with contaminated water, perhaps central heating systems, and swimming pool circulators, but  these do not commonly pass out of the building under terra-firma and back in again. If a metal pipe comes in and changes to plastic - the opposite of the case here I think, then it is sometimes just easier to box in or cover the short section so it cannot be touched.

Mike.

I assume you are looking at 544.1.2.  The wording has not changed in my copy of BS7671 andt 2, are you referring to the latest GN8?

Don’t shoot the messenger that came straight out of the mouth of a JPEL64 Wiring Regulations committee member.

Apparently the gas industry said that they were installing insulated fittings into the gas supply pipework entering buildings, therefore a Main Protective Bonding conductor was not required, but these fittings leaked gas so they have been removing them.

Also people were passing off installations with there being a couple of metres or more of metallic pipe inside a building upfront of the insulated section, which was usually the situation with gas pipework anyway.

So an electrician cannot say the there definitely is and insulated section in gas supply pipework that will remain in place and in many situations no one will touch the section of metal pipework upfront of the insulated section and that after it at the same time.

So it avoid any confusion it’s just easier to say “No!”.

Therefore, it actually needs to be yellow gas or blue water MPDE or black alkathene water pipe coming into the building without any visible metallic pipe. 

Really Andy? NOTHING of any kind should leak from that source. Tell your mate? that this is NOT the regulation as it stands and it is deliberate misinformation. Main Bonding is still only required if the internal pipework is extraneous, and if you think about it a tiny bit, this is perfectly sensible. When a change appears in BS7671 you will be told, until then......

I suppose that you would code the insulated section situation as C1? Now think just how?

To me the "only a metre or two coming out of the ground therefore not requiring bonding" thinking  is not usually a good idea in my opinion. Can it be touched/might it be touched as well as touching something else would be my first thought, even if fairly unlikely. If, on the other hand it is extremely unlikely then yes you could be introducing a potential danger that would not already exist

It is a somewhat muddled situation - 544.1.2 specifies the bond be on the consumer's side of the position of a possible insulating joint (i.e. at the meter) so that the whole purpose of the insulating joint (IJ) isn't defeated and the gas people don't end up with diverted N currents flowing around their pipework when they don't want that. On the other hand basic physics wants all internal pipework bonded where it is (or at risk of being) extraneous - logically including any metallic section between where it comes out of the ground or enters the building, and the meter (where the meter is internal). You won't find PE gas pipes internally as they're not sufficiently fire resistant for the gas regs.

For me if there's any doubt as to the presence (or future reliability) of an IJ - then bond after the meter and ensure that any metallic pipework before the meter is covered with insulating material so it can't be touched (or can't introduce a potential into the installation, in definition terms).

We are departing somewhat from the original question however. As has already been said, 543.2.6 lays down the requirements for using an extraneous-conductive-part as a protective conductor. In a domestic situation (iii) (precautions shall be taken against its removal) is likely to be hard to achieve - as even the removal of a small section of pipe - e,g. to insert a plastic fitting - during alterations or repairs would be a problem. In some controlled environments - e.g. where there are permits-to-work and everything is organised though a single authority who oversees all work undertaken, you could have something written into the appropriate procedures and have some confidence in it being taken account of, but in a domestic situation where plumbers are likely to work without any detailed technical control, I would be far more dubious. Even the ordinary "safety electrical connection - do not remove' labels don't seem to be properly understood by a significant number of domestic plumbers, so you'd have a hard job to convince me that any kind of labelling alone would suffice.

   - Andy.