main equipotential bonding to gas

[JohnW2]

I'm not sure how joe public is going to get his hands on a line or neutral part, so they wouldn't need bonding.

Not only that (albeit the definition of extraneous-c-p says nothing about it having to be 'touchable'!) but, in fact, I actually owe BS7671 an apology. Having just looked, the definition of extraneous-c-p actually ends up with "... and not forming part of the electrical installation." - so not a sloppy definition at all.

Kind Regards, John

 

[RF Lighting]

Makes a change for the IET!

 

[JohnW2]

Makes a change for the IET!

... stillp doesn't like us 'blaming' the IET for the content of BS7671 - perhaps we should say JPEL/64! Mind you, perhaps it's different when we are praising, rather than 'blaming' the document !!

Kind Regards, John

 

[Taylortwocities]

The gas men will make a joint approx 2 metres from your property and run a new lovely yellow pipe to the new meter position.

This new pipe is now made of plastic (I asked a gas fitter this very question today). If it is plastic it cannot introduce an earth potential, is not an extraneous-conductive-part and so bonding will not be required either inside the meter box, at the point of entry to the house, or anywhere.

 

[JohnW2]

The gas men will make a joint approx 2 metres from your property and run a new lovely yellow pipe to the new meter position. This new pipe is now made of plastic (I asked a gas fitter this very question today). If it is plastic it cannot introduce an earth potential, is not an extraneous-conductive-part and so bonding will not be required either inside the meter box, at the point of entry to the house, or anywhere.

It seems that's not universal. A member of my family had her gas meter moved outside a couple of years ago and, somewhat to my surprise, it was plumbed in metal all the way to the new meter.

The person who fitted it left the previous main bonding to indoor pipework in place, but put a thin (I think probably 2.5mm²) G/Y strap across the lovely new meter

Kind \regards, John

 

[PrenticeBoyofDerry]

The gas men will make a joint approx 2 metres from your property and run a new lovely yellow pipe to the new meter position.

This new pipe is now made of plastic (I asked a gas fitter this very question today). If it is plastic it cannot introduce an earth potential, is not an extraneous-conductive-part and so bonding will not be required either inside the meter box, at the point of entry to the house, or anywhere.

As John has mentioned this not always done, but the point is a fair one. So if the gas supply pipe is of the insulated type (MDPE), then bonding to the gas pipes consumer side can be excluded, this would need verifying.
This is also true of water service supply pipes.

 

[RF Lighting]

I found a water supply to a fairly new house today. Supply pipe was blue mdpe plastic which terminated straight into the stop cock. There was then 2" of copper pipe before it turned back into plastic. Some muppet had gone to all the trouble of bonding the copper pipe

 

[JohnW2]

I found a water supply to a fairly new house today. Supply pipe was blue mdpe plastic which terminated straight into the stop cock. There was then 2" of copper pipe before it turned back into plastic. Some muppet had gone to all the trouble of bonding the copper pipe

Let's just hope that it wasn't an 'electrician'

Kind Regards, John

 

[JBR]

The gas men will make a joint approx 2 metres from your property and run a new lovely yellow pipe to the new meter position.

This new pipe is now made of plastic (I asked a gas fitter this very question today). If it is plastic it cannot introduce an earth potential, is not an extraneous-conductive-part and so bonding will not be required either inside the meter box, at the point of entry to the house, or anywhere.

Sorry to interpose here, but this thread fits almost exactly with what happened to us recently.

The gas people have been replacing old supply pipes in the road and also the pipes that extend to domestic properties.

For one reason or another (which I needn't bore you with) they decided it would be best to remove the meter from where it was inside the house (which was originally external before an extension was built - before we moved in, I hasten to add) to an external location at the other end of the house. I happily agreed to this (the alternative would be to have gas pipes running up the wall internally!) and the work was done.

As above, the supply pipe now running under our drive is yellow plastic, right up to the vertical (metal) pipe from ground level to the meter, so I take the point that no external earth potential is likely to be introduced.

The fitter did ask where my electricity meter is, and explained about having to bond from the gas meter to the electricity meter (or near to it), but unfortunately the two are separated by about forty feet or more. For that reason, he said it would be acceptable to leave the existing bonding on the pipe at the old gas meter location, and which is still 'live' and connected to the internal gas piping.

I should add that this existing bonding wire extends from the internal gas pipe down under the floor, but beyond that I have no idea where it goes.

I am assuming, from what you say above, that this is a safe option. Should I have someone check where that bonding wire goes to?

 

[EFLImpudence]

As above, the supply pipe now running under our drive is yellow plastic, right up to the vertical (metal) pipe from ground level to the meter, so I take the point that no external earth potential is likely to be introduced.

Correct

The fitter did ask where my electricity meter is, and explained about having to bond from the gas meter to the electricity meter (or near to it), but unfortunately the two are separated by about forty feet or more. For that reason, he said it would be acceptable to leave the existing bonding on the pipe at the old gas meter location, and which is still 'live' and connected to the internal gas piping.

Live is probably not the most accurate description.

I should add that this existing bonding wire extends from the internal gas pipe down under the floor, but beyond that I have no idea where it goes.

I am assuming, from what you say above, that this is a safe option. Should I have someone check where that bonding wire goes to?

If you mean to check it is satisfactory then - yes.
You could do it yourself by disconnecting it from the pipe and ensuring continuity with the Main Earthing Terminal.

If none of the gas pipes now has any contact with the ground then the bonding conductor is not really needed now but will do no harm to be left connected.

 

[JohnW2]

If none of the gas pipes now has any contact with the ground then the bonding conductor is not really needed now but will do no harm to be left connected.

In practice, that will very often be true, since the (necessarily metal) gas pipework will very commonly already be connected to earth via boilers, continuity with metal water pipework and the CPCs of central heating controls, immersions etc. etc.

However, if that is not true (possible if there is no gas CH) then, as you are currently arguing in another thread (and I agree with you) it then theoretically could 'do harm to leave bonding connected to that pipework' (which would not be an extraneous-c-p, and would not be otherwise earthed), since that bonding would introduce a hazard which would not be present if the ('unnecessary') bonding were removed.

Kind Regards, John

 

[EFLImpudence]

If none of the gas pipes now has any contact with the ground then the bonding conductor is not really needed now but will do no harm to be left connected.

In practice, that will very often be true, since the (necessarily metal) gas pipework will very commonly already be connected to earth via boilers, continuity with metal water pipework and the CPCs of central heating controls, immersions etc. etc.

However, if that is not true (possible if there is no gas CH) then, as you are currently arguing in another thread (and I agree with you) it then theoretically could 'do harm to leave bonding connected to that pipework' (which would not be an extraneous-c-p, and would not be otherwise earthed), since that bonding would introduce a hazard which would not be present if the ('unnecessary') bonding were removed.

Again true, perhaps I should have asked but -

I think it very unlikely that JBR does not have central heating and at least one earthed gas appliance.

 

[JohnW2]

Again true, perhaps I should have asked but - I think it very unlikely that JBR does not have central heating and at least one earthed gas appliance.

You are, of course, very probably (but not inevitably) right. Until she died, not many years ago, I had an elderly relative who had an old gas cooker (no electric ignition) and several gas fires, but no CH or any other gas appliances (apart from the capped remnants of a few gas lights on the walls ). If her gas supply had been plastic all the way to an external meter, I suspect that all her gas pipework would have been 'floating'.

In terms of the education of any readers, I think the important point is that there is never any harm in 'unnecessarily' bonding pipework which is already connected to earth in one way or another (as it nearly always will be these days), but that if, unusually, it has no connection to earth and bonding is not required, 'unnecessary' bonding has the potential to introduce hazards.

Kind Regards, John

 

[JBR]

The fitter did ask where my electricity meter is, and explained about having to bond from the gas meter to the electricity meter (or near to it), but unfortunately the two are separated by about forty feet or more. For that reason, he said it would be acceptable to leave the existing bonding on the pipe at the old gas meter location, and which is still 'live' and connected to the internal gas piping.

Live is probably not the most accurate description.

If none of the gas pipes now has any contact with the ground then the bonding conductor is not really needed now but will do no harm to be left connected.

Thanks. Yes, I can understand that 'live' is perhaps not the best term to use, especially on an electrics forum. I just thought it would be quicker and easier to say that rather than 'still connected to the gas supply and containing gas at mains pressure'!

I appreciate your advice and am quite sure everything is safe here, as none of the gas pipes are now in contact with the ground, except for the old one which fed the original meter and has now been disconnected from any other pipework in the house.

(The main reason I asked earlier was that someone suggested that pipes should be connected/bonded to a point near or at the electricity meter. I think they might have said 600mm.)

 

[EFLImpudence]

I appreciate your advice and am quite sure everything is safe here, as none of the gas pipes are now in contact with the ground, except for the old one which fed the original meter and has now been disconnected from any other pipework in the house.

Strictly speaking the old pipe should still be main bonded so don't go playing with it.

(The main reason I asked earlier was that someone suggested that pipes should be connected/bonded to a point near or at the electricity meter. I think they might have said 600mm.)

It will be connected to the Main Earthing Terminal.
600mm. has nothing to do with it.

The MET will be either a block near the meter or consumer unit or the earth bar in the consumer unit.