18th edition - where to bond gas supply pipe, if at all?
- Thread starter fjhugh
- Start date
Sponsored Links
OK - so, as I asked in my edit, does that mean that you believe that one should "certainly not" bond any extraneous-c-ps in a TN-C-S installation?
Kind Regards, John
Read exactly what I have said about THIS situation, I stand by every word.
Sponsored Links
I wish I was able to see underground, but I can't therefore I have no idea what the old gas pipe could be touching, but I do know it could be touching something and that's why it should be insulated.
Yes correct, where its all steel they are connected together but when changed to plastic that stops happening.the existing steel is chopped up into lots of little pieces to be able to slide the plastic pipe in.
Oh no its not, you are guessing and you are wrong, they do not dig up the road to chop up the pipe. They push and pull the plastic as far possible, then they dig a hole - and so on.
As I've said, in terms of the risk of very high currents flowing in bonding conductors as a result of a fault on the CNE of a TN-C-S supply, "THIS situation" is no different from any other in which one bonds any extraneous-c-p in such an installation.
(To be hyper critical) as the pipework is not an extraneous-c-p, it is nothing to do with 411.3.1.2 nor Chapter 54.
Surely that reading would indicate that the pipe IS main bonded. Very accurate meter?
411.3.1.2 does state:
"Metallic pipes entering the building having an insulating section at their point of entry need not be connected to the
protective equipotential bonding."
Whether one agrees with that or not, that is what it says.
However, is the insulating section in fact AT the point of entry? If one thinks not then presumably it requires the main bonding.
Is insulating a pipe a recognised alternative for main bonding?
Presumably anyone working on the pipe in the future would prefer it to be bonded (even if they do not understand the principles and would likely bond the wrong pipes with their bonding jumper cable).
Apologies my typo.. MET to supply pipe is 0.0012 Megaohms.
I was expecting it to be higher as from what I can see the pipe looks to be steel covered in a thick yellow plastic coating for its length under the house until it elbows and comes up. Of course I can't see what happens on the other end.
I agree the location is questionable. It would be interesting to see what guidance the gas standards give.
Perhaps in this case insulating would be a better alternative to main bonding the supply side? I can't imagine any neighbours have moved their bonding to before the meter. This supply pipe might then be the only bonded gas pipe for the entire street. A broken PEN conductor and one old jointed steel pipe with a live plastic gas pipe within it doesn't sound ideal. I can't help but feel that the gas engineers have placed insulating sections for a reason, albeit executed poorly.
Last edited:
I suppose that depends upon how well 'insulated' it is and how 'durable' the insulation is considered to be. If it is considered that the insulation is 'good enough' and likely to remain so, then it is arguably not a 'conductive part' at all, and certainly not "liable to introduce a potential" - so not an extraneous-c-p. If it's not an extraneous-c-p, then it doesn't need bonding. I'm not sure I would personally describe that as 'the insulation being an alternative to main bonding', since it's really a matter of main bonding not being required (if insulation means that the pipe is not an extraneous-c-p).
They would presumably only prefer it to be bonded if they did not trust the insulation to be, and that it would remain, adequate. In any event, in the OP's case, it's hard to see why anyone would ever need to 'work on' the pipe, which is now seemingly only being used as a conduit for the plastic pipe within it - but if they did do 'work' which involved damaging/destroying the insulation, that would obviously move the goalposts.
Kind Regards, John
Yes, but we are not talking about that.
It is wrapped in tape. I do not recollect the regulation stating that extraneous-c-ps must be main bonded - or wrapped in tape.
I thought that was the situation - although it could easily still be touched when changing the meter or pipes - but now fjhugh has said "from what I can see the pipe looks to be steel covered in a thick yellow plastic coating for its length under the house until it elbows and comes up." so is it the case that the metal is in fact the supply pipe?
At this rate we will be looking at insulating the ground around the building.
Consider the case of someone standing on the ground and putting their hand in though a window.
QUICK put a main bonding connection onto that wrist.
Sorry I wasn’t clear.. the original supply pipe is metallic/steel. however the length of it running under the house looks to be steel coated in yellow plastic. That is all the old supply.
SGN have since fed a new plastic PE pipe into this steel/steel coated pipe.
Oh for heavens sake Sparx I'm only telling what happened in my street and having spoken with others it seems to be what generally happens. But I'm not going to be silly enough to say it's what always happens.
I'm not wrong, and I rather resent being accused of being so when I post a factual statement in good faith, when I posted this:
In our case they located where every branch off the main was and dug a hole, mostly using pneumatic drill and massive vacuum cleaner. Note; they dug the holes well before there was any sign of yellow pipe on site.
They cut the branch about 400-500mm from the main and cut about 400mm out of the main, ie the whole of the tee was removed.
They pulled a plastic pipe into the original main about a dozen properties worth at a time. such that there was an exposed section of plastic in every gap, cut a hole in the new pipe and welded a branch fitting in place.
They pulled a plastic pipe into each property and welded it to the branch.
They make absolutely no effort to bond the steel sections and after wrapping the ends of the steel/plastic pipe exit with black PVC tape the hole was filled with either sand or soft soil [like top soil] to cover over the pipework, filled with crappy stuff then topped off with concrete slab and Asphalt.
I haven't bothered explaining the house end as I don't think there's a requirement for this thread.
In my case the exposed steel supply pipe is some 5-6Ω to the MET [lead sheathed supply cable]
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
