Gas pipe earth???

[dylanlennon]

My gran just got a gas fire installed, the plumber clipped the pipe round the bottom of the house from gas canister in back garden to fire. The metalwork ain't earthed. What's the easiest option to earth it as I assume it needs it, small earth rod & link onto pipework? Is this satisfactory?

 

[Electrifying]

The gas pipe doesn't need 'earthing' - it may require 'bonding' if it is deemed to be 'extraneous' where it enters the property.

 

[JohnW2]

The gas pipe doesn't need 'earthing' - it may require 'bonding' if it is deemed to be 'extraneous' where it enters the property.

Given the nature of this forum, I think that answers like that can easily confuse an OP, and certainly are unlikely to be understood by them. It might be more understandable if you explained that what you're saying is that 'bonding' is the correct technical term for connecting some pipework with wires to the 'earth' of a house's electrical installation, and also if you explained what is meant by the technical term 'extraneous'.

However, the one important thing you didn't say is that, if the pipe does need bonding, then to do as the OP suggests (connect it to an earth rod) is the very last thing he should do (thereby dramatically illustrating that there is a difference between 'earthing' and bonding).

Kind Regards, John

 

[bernardgreen]

Earthing and bonding. Good thing the wires know which way to let the current flow. Green with yellow stripe = Bonding, Yellow with green stripe = Earthing --- JOKE ---

A hill top site with emergency generators and emergency gas heating and regulations from several different "authorities".

The gas bottles did have to be earthed to an ground rod ( gas bottle safety regs ) and the gas pipes had to be bonded as they entered the building ( electrical safety regs ). It was the non conductive non metallic gas tubing that separated bonding from earthing that allowed this to happen without making a connection between bonding wires and earthing wires.

Non conductive tubing that was also conductive to prevent build up of static charges that could have created a spark when bottles were being changed.

Of course the bonding was connected to ground via the earthed star point of the transformer in the adjacent substation. Then there was the isolated clean earth for the computor and comms equipment.

 

[JohnW2]

dylanlennon ... please see bit for you below...

Earthing and bonding. Good thing the wires know which way to let the current flow. Green with yellow stripe = Bonding, Yellow with green stripe = Earthing --- JOKE ---

Bernard: As you know, I have a lot of sympathies/agreements with your viewpoint, but the case being dicsussed here is obviously an example of a situation in which the 'overlap' between 'earthing' (at least, in one sense) and bonding is not a two-way one. If the gas pipe were main bonded, in the usual way, to the installation's MET, that would certainly also 'earth' it in one sense, since the MET is obviously usually connected to earth via a low impedance path, and usually at a potential fairly close to true earth. However, to earth the gas pipe in the way the OP suggested (installing and connecting an earth rod to it), that would most certainly not provide the required bonding. On the contrary, it would make it even more certain that if, due to a fault, the MET/CPCs rose to a high potential above true earth, a dangerous potential difference would then exist between the gas pipework and exposed-conductive-parts of the installation.

To dylanlennon: To explain this to you. IF the gas feed pipe could represent a path to earth (e.g. if any of it is buried), which makes it what electricians call an 'extraneous-conductive-part', then there is a requirement for 'bonding'. This consists of a thick (usually 10mm²) wire connecting the pipe (close to where it enters the house) to the 'Main Earth Terminal' of your house's electrical installation (usually near the meter and/or consumer unit), The reason is to prevent a dangerous voltage difference (which could result in electric shocks) arising between the gas pipe (and fire) and other metalwork in the house in the case of certain types of fault.

If the gas pipe is in no way connected to earth, then there is no need/requirement for that bonding - that could be the case if the pipe doesn't go anywhere near the ground and is not electrically connected to earth via the gas cylinder (cylinder raised off ground by insulating material or connected via an electrically non-conducting hose {beware - some flexible gas hoses are electrically conductive}). If any gas regulations require the cylinders to be earthed (I don't know), that could be done in the way you suggest (connect to a local earth rod) - but, in that case, you would definitely have to have 'bonding' of the pipework in the house, as above. Opinions will probably vary as to whether you need that bonding, and you therefore really need an electrician to look at the exact situation to decide whether you need bonding to be installed.

Kind Regards, John

 

[EFLImpudence]

Then there was the isolated clean earth for the computor and comms equipment.

Oxymoron?

 

[EFLImpudence]

dylanlennon

Only parts which are themselves connected to earth - the planet or the installation - may require bonding to equalise potential voltages.

The purpose of bonding is NOT to ensure operation of a fuse or circuit breaker.

 

[JohnW2]

Only parts which are themselves connected to earth - the planet or the installation - may require bonding to equalise potential voltages. The purpose of bonding is NOT to ensure operation of a fuse or circuit breaker.

IF the gas feed pipe could represent a path to earth (e.g. if any of it is buried), which makes it what electricians call an 'extraneous-conductive-part', then there is a requirement for 'bonding'. ... The reason is to prevent a dangerous voltage difference (which could result in electric shocks) arising between the gas pipe (and fire) and other metalwork in the house in the case of certain types of fault. ... If the gas pipe is in no way connected to earth, then there is no need/requirement for that bonding - that could be the case if the pipe doesn't go anywhere near the ground and is not electrically connected to earth via the gas cylinder ....

Are we saying anything different?

Kind Regards, John

 

[EFLImpudence]

No.

I don't automatically disagree with you.

Just succinctly making the point that only already earthed parts are bonded and it is not to blow the fuse.

Oops, I've done it again.

 

[JohnW2]

No. I don't automatically disagree with you. Just succinctly making the point that only already earthed parts are bonded and it is not to blow the fuse. Oops, I've done it again.

Indeed you have

Whilst I'm sure it's true that teh succinct approach of yourself and others is preferable to my non-succinct approach, on this occasion I thought that the OP would probably benefit from a little more detailed explanation, given some of the otehr posts in the thread.

Kind Regards, John

 

[EFLImpudence]

I thought I'd offer a précis just in case.

 

[dylanlennon]

dylanlennon ... please see bit for you below...

Earthing and bonding. Good thing the wires know which way to let the current flow. Green with yellow stripe = Bonding, Yellow with green stripe = Earthing --- JOKE ---

Bernard: As you know, I have a lot of sympathies/agreements with your viewpoint, but the case being dicsussed here is obviously an example of a situation in which the 'overlap' between 'earthing' (at least, in one sense) and bonding is not a two-way one. If the gas pipe were main bonded, in the usual way, to the installation's MET, that would certainly also 'earth' it in one sense, since the MET is obviously usually connected to earth via a low impedance path, and usually at a potential fairly close to true earth. However, to earth the gas pipe in the way the OP suggested (installing and connecting an earth rod to it), that would most certainly not provide the required bonding. On the contrary, it would make it even more certain that if, due to a fault, the MET/CPCs rose to a high potential above true earth, a dangerous potential difference would then exist between the gas pipework and exposed-conductive-parts of the installation.

To dylanlennon: To explain this to you. IF the gas feed pipe could represent a path to earth (e.g. if any of it is buried), which makes it what electricians call an 'extraneous-conductive-part', then there is a requirement for 'bonding'. This consists of a thick (usually 10mm²) wire connecting the pipe (close to where it enters the house) to the 'Main Earth Terminal' of your house's electrical installation (usually near the meter and/or consumer unit), The reason is to prevent a dangerous voltage difference (which could result in electric shocks) arising between the gas pipe (and fire) and other metalwork in the house in the case of certain types of fault.

If the gas pipe is in no way connected to earth, then there is no need/requirement for that bonding - that could be the case if the pipe doesn't go anywhere near the ground and is not electrically connected to earth via the gas cylinder (cylinder raised off ground by insulating material or connected via an electrically non-conducting hose {beware - some flexible gas hoses are electrically conductive}). If any gas regulations require the cylinders to be earthed (I don't know), that could be done in the way you suggest (connect to a local earth rod) - but, in that case, you would definitely have to have 'bonding' of the pipework in the house, as above. Opinions will probably vary as to whether you need that bonding, and you therefore really need an electrician to look at the exact situation to decide whether you need bonding to be installed.

Kind Regards, John

Thanks for the explanation John. I don't think an earth is needed then as there is nothing buried, the gas canister is just sitting on the gravel. Another quick question, since were on the subject, my new garage door frame is steel, now I've seen some similar doors that were bonded although I'm sure the steel was buried, they were earthed with a 10mm but mine is not. Now as far as I can see (I'll post a picture or two) this is not buried, it's sitting on top of bits of wood. So should this be bonded from garage consumer unit or not?

 

[JohnW2]

Thanks for the explanation John. I don't think an earth is needed then as there is nothing buried, the gas canister is just sitting on the gravel.

It's not necessarily as simple as that. "Just sitting on gravel" (which presumably can sometimes get very wet) in conjunction with conductive hoses might represent a significant current path to earth. As I said, you relly need to get an electrician to assess the situation and, if necessary, make some measurements.

Another quick question, since were on the subject, my new garage door frame is steel, now I've seen some similar doors that were bonded although I'm sure the steel was buried, they were earthed with a 10mm but mine is not. Now as far as I can see (I'll post a picture or two) this is not buried, it's sitting on top of bits of wood. So should this be bonded from garage consumer unit or not?

Same issue. Only someone on-site can really make a judgment (aided, if necessary, measurements) as to whether bonding is required. If the wood is likely to get wet, it could be needed. If the decision is that bonding is required, the other issue that only an on-site electrician can decide is where that metalwork needs to be bonded to - garage CU or house CU (MET). That will depend upon the way the earthing in the garage has been arranged and, if appropriate, the size of the wire connecting the garage CU to the Main Earthing Terminal (MET) in the house.

Kind Regards. John

 

[bernardgreen]

Then there was the isolated clean earth for the computor and comms equipment.

Oxymoron?

The equipment ( 0 volt lines, chassis' coaxial screens and armouring etc etc ) was earthed to the station's ground mat via direct conductors so that the potential on the CPC could not affect the equipment. Most electrical cable and switchgear was "protected" by the CPC

 

[dylanlennon]

Thanks for the explanation John. I don't think an earth is needed then as there is nothing buried, the gas canister is just sitting on the gravel.

It's not necessarily as simple as that. "Just sitting on gravel" (which presumably can sometimes get very wet) in conjunction with conductive hoses might represent a significant current path to earth. As I said, you relly need to get an electrician to assess the situation and, if necessary, make some measurements.

Another quick question, since were on the subject, my new garage door frame is steel, now I've seen some similar doors that were bonded although I'm sure the steel was buried, they were earthed with a 10mm but mine is not. Now as far as I can see (I'll post a picture or two) this is not buried, it's sitting on top of bits of wood. So should this be bonded from garage consumer unit or not?

Same issue. Only someone on-site can really make a judgment (aided, if necessary, measurements) as to whether bonding is required. If the wood is likely to get wet, it could be needed. If the decision is that bonding is required, the other issue that only an on-site electrician can decide is where that metalwork needs to be bonded to - garage CU or house CU (MET). That will depend upon the way the earthing in the garage has been arranged and, if appropriate, the size of the wire connecting the garage CU to the Main Earthing Terminal (MET) in the house.

Kind regards John

I see. Well when you say measurements I assume you mean with one of those multitesters. My brother who's away travelling has left all his tools in my garage as he's renting his flat out, he's a sparky you see. He has a Megger MFT1552 tester so you know what the next question is going to be don't you?! How do I test & what values am I looking for? See if the garage door was bonded & didn't need to be, is that dangerous?