Does this oil pipe need bonding?

[Jon c]

Hi all,

Recently had an oil boiler moved to make space in the room, the plumber that did it insisted that the oil pipes need bonding however I'm not so sure. Property has TT earthing. My understanding was that pipes generally only need bonding if they are extraneous, i.e. are metal and run underground. However the oil pipe from the tank is a plastic coated microbore copper pipe, and it runs from the above ground oil tank over maybe 5 metres on top of old stone paving. Basically it never actually goes underground and even if it did its plastic coated.

Previously the oil pipes were actually bonded however practically every visible bit of copper pipe in the house is as well so think there's been a bond happy electrician at some point.

I know the only way to know for certain is to carry out a test however would appreciate any input based on the given info or if anyone knows if there's different rules for bonding oil pipes.

Also another question is if they do need bonding, the 10mm conductor is now a foot or so too short since moving the boiler, so what is the best way of extending it? Replacing its entire length would involve pulling up floorboards so not a preferable option. Plumber has currently left it not bonded as he didn't have any kit to extend the conductor.

Thanks for any advice!

 

[DetlefSchmitz]

I think this is one of those personal opinion things. When I had all the floors up and replaced the bonding to our incoming water, I made a loop past the oil boiler with the intention of bonding the oil pipe which is similar to yours but crosses under a concrete path in plastic coating. I never got round to making the final connection. I have seen several opinions on here and also from someone who fitted a replacement boiler. I haven't seen anyone thinking it's needed. But you are right in that the definitive way is to measure the resistance to earth, I guess with the pipe disconnected from the boiler.

 

[Sureitsoff?]

When my neighbours house got sold the buyers insisted that a new c/u got fitted (i would have told the buyers to f off personally) and the electrician that did the work put an earth rod at the tank end of the pipe and the house end just before the pipe entered the garage .

 

[JohnW2]

I think this is one of those personal opinion things.

I agree

.... But you are right in that the definitive way is to measure the resistance to earth, I guess with the pipe disconnected from the boiler.

As I often debate with EFLI, undertaking measurements to determine whether something constitutes an extraneous-c-p (which needs main bonding) is all very well, but relates only to a single point in time.

I usually cite my LPG supply pipe. The final (short) outdoor part is metal, everything upstream being plastic. That bit of metal pipe travels through (not very close to the bottom of) a pretty deep 'pit' full of gravel. If one undertook a measurement (as you say, with pipe disconnected from boiler) during a very 'dry spell', one would almost certainly conclude that it didn't need bonding, but the situation could become very different during a 'very wet' period.

Given that the oil (or LPG) pipe will inevitably be earthed via the boiler, the theoretical issue (which EFLI would undoubtedly cite) of the undesirability of 'unnecessarily earthing' something does not really arise - so one could argue that the 'safest' approach (which would 'do no harm') would be to bond?

It's interesting that we rarely see this discussion about natural gas pipes, which most (perhaps 'unthinking'?) people seem to regard as always requiring bonding, almost regardless of the 'actual situation'.

Kind Regards, John

 

[EFLImpudence]

... and the electrician that did the work put an earth rod at the tank end of the pipe and the house end just before the pipe entered the garage .

That would certainly ensure that the pipe did require bonding.

 

[EFLImpudence]

I agree

As I often debate with EFLI, undertaking measurements to determine whether something constitutes an extraneous-c-p (which needs main bonding) is all very well, but relates only to a single point in time.

I usually cite my LPG supply pipe. The final (short) outdoor part is metal, everything upstream being plastic. That bit of metal pipe travels through (not very close to the bottom of) a pretty deep 'pit' full of gravel. If one undertook a measurement (as you say, with pipe disconnected from boiler) during a very 'dry spell', one would almost certainly conclude that it didn't need bonding, but the situation could become very different during a 'very wet' period.

...but measuring while connected will probably tell one if the entry point is connected to or isolated from the house earth.

Given that the oil (or LPG) pipe will inevitably be earthed via the boiler, the theoretical issue (which EFLI would undoubtedly cite) of the undesirability of 'unnecessarily earthing' something does not really arise - so one could argue that the 'safest' approach (which would 'do no harm') would be to bond?

Agreed - allowing for the positions of various parts.

It's interesting that we rarely see this discussion about natural gas pipes, which most (perhaps 'unthinking'?) people seem to regard as always requiring bonding, almost regardless of the 'actual situation'.

Not sure what you mean. How would a metal gas pipe not be an extraneous-c-p?

 

[JohnW2]

...but measuring while connected will probably tell one if the entry point is connected to or isolated from the house earth.

I don't really understand. Assuming you mean 'with the pipe connected to boiler', it will almost inevitably show that the pipe is 'connected' (low resistance/impedance) to the house earth (MET), albeit the path to MET may be partially though a ('low CSA') CPC - but that surely does not help one to know whether the pipe requires main bonding, does it?

Not sure what you mean. How would a metal gas pipe not be an extraneous-c-p?

Several possibilities, I would have thought. What about a pipe coming from an above-ground external meter which is supplied by a plastic pipe and/or has no electrical continuity across the meter?

Kind Regards, John

 

[EFLImpudence]

I don't really understand. Assuming you mean 'with the pipe connected to boiler', it will almost inevitably show that the pipe is 'connected' (low resistance/impedance) to the house earth (MET), albeit the path to MET may be partially though a ('low CSA') CPC - but that surely does not help one to know whether the pipe requires main bonding, does it?

Agreed - but if the measurement shows no continuity between the point of entry and the MET then there likely is an insulating section somewhere and the point of entry is not an extraneous-c-p.

Like your following example.

Several possibilities, I would have thought. What about a pipe coming from an above-ground external meter which is supplied by a plastic pipe and/or has no electrical continuity across the meter?

There are all sorts of possibilities.

 

[JohnW2]

Agreed - but if the measurement shows no continuity between the point of entry and the MET then there likely is an insulating section somewhere and the point of entry is not an extraneous-c-p.

In practical terms, I don't really get that. It is surely extremely unlikely that there would be an 'insulating section' in a metal gas/oil pipe between entry into the building and the boiler (hence MET, via CPCs), isn't it?

There are all sorts of possibilities.

As I said, indeed there are - but your previous comment seemed to suggest/imply that there weren't?

Kind Regards, John

 

[EFLImpudence]

In practical terms, I don't really get that.

Is that not exactly what your example illustrated?

It is surely extremely unlikely that there would be an 'insulating section' in a metal gas/oil pipe between entry into the building and the boiler (hence MET, via CPCs), isn't it?

Well, very likely for water with plastic pipes installed anywhere and even for gas the insulating section is at the meter.

As I said, indeed there are - but your previous comment seemed to suggest/imply that there weren't?

That was not my intention.

 

[JohnW2]

Is that not exactly what your example illustrated?

Not that I can see. In my example there was no 'insulation section' in the pipe within the building - and,as i said,such would surely be extremely unlikely for an oil or gas pipe?

Well, very likely for water with plastic pipes installed anywhere and even for gas the insulating section is at the meter.

True - but we (at least,I) were talking about oil and gas pipes.

That was not my intention.

Maybe not your intention, but I feel sure that your "... How would a metal gas pipe not be an extraneous-c-p?" would be taken by most people (certainly me) to indicate that you were suggesting that it was 'no possible' ,or something approaching that.

Kind Regards, John

 

[EFLImpudence]

Maybe not your intention, but I feel sure that your "... How would a metal gas pipe not be an extraneous-c-p?" would be taken by most people (certainly me) to indicate that you were suggesting that it was 'no possible' ,or something approaching that.

A metal gas pipe.

That is all metal throughout its run from the supply.

 

[JohnW2]

A metal gas pipe. That is all metal throughout its run from the supply.

Quite so - and, as I said, if it originated from an above-ground external meter whose outlet was not in continuity with earth (supplied with plastic pipe and/or no continuity between input and outlet of meter), then it would not be an extraneous-c-p, regardless of what measurements one undertook.

Kind Regards, John

 

[EFLImpudence]

Quite so - and, as I said, if it originated from an above-ground external meter whose outlet was not in continuity with earth (supplied with plastic pipe and/or no continuity between input and outlet of meter), then it would not be an extraneous-c-p, regardless of what measurements one undertook.

It would - but were it not connected to the MET either (by whatever means), then the measurement would verify that it was not an extraneous-c-p.

 

[JohnW2]

It would - but were it not connected to the MET either (by whatever means), then the measurement would verify that it was not an extraneous-c-p.

It would. However, as I said, in the case of a gas (or oil) pipe, in practice it just isn't going to happen (at least, virtually never) that there is any 'insulating section' in the pipework within the building - although, as we've agreed, it's quite possible with water pipes.

Kind Regards, John