mains gas pipe bonding,?

[joesoap1]

Hi, Does anyone know the legal requirements regarding the bonding of the mains gas pipe from the meter to the boiler? Does it have to be within a certain distance from the meter, or anywhere along its length, in my case approx 40 feet.

 

[expertgasman]

Hi, Does anyone know the legal requirements regarding the bonding of the mains gas pipe from the meter to the boiler? Does it have to be within a certain distance from the meter, or anywhere along its length, in my case approx 40 feet.

Within 600mm of meter, before any tee.

 

[Agile]

If its an external meter and some way from, for example an upstairs flat fed externally, its accepted that the earth bond can be where the gas pipe comes into the flat but still be left visible or inspectable.

In fact Nat Grid seem to recommend that position although its not based on any gas rules or legislation. Sound advice in many cases though.

Tony

 

[joesoap1]

If its an external meter and some way from, for example an upstairs flat fed externally, its accepted that the earth bond can be where the gas pipe comes into the flat but still be left visible or inspectable.

In fact Nat Grid seem to recommend that position although its not based on any gas rules or legislation. Sound advice in many cases though.

Tony

Hi Tony, just had Homeserve do a inspection on boiler, couldn,t see bonding on gas pipe at meter, written warning.I thought it was inside of wall, underfloor, aesy to get to.However, none at all.I also cannot see any on water pipes, which come in as lead.Does water need bonding if it,s lead underground? Can I bond gas 600ml from meter to water pipe income, just about 7 metres apart? cheers.

 

[Agile]

Water pipes no longer need to be bonded as most have plastic sections so cannot be relied on to be good earth.

A gas pipe must NOT be specifically bonded to a water pipe and MUST be taken to the main earthing terminal at the meter which is usually conected to the cable sheath.

A lead water pipe can be used as a radio reception earth to counterbalance the active antenna part. Its a true earth and does not carry mains borne interference.

Tony

 

[mikely]

Both gas and water must be bonded to the main earthing terminal (MET) of the installation using 10mm2 cable. These can either be run separately or via one unbroken cable linking both to the MET. See this article for more information: http://electrical.theiet.org/wiring-matters/22/bonding.cfm?type=pdf

 

[Agile]

Thats interesting. Perhaps I am wrong when I said its no longer needed to bond incoming water pipes. I also thought that 6mm was adequate.

Of course they would be bonded at bathrooms anyway.

Tony

 

[joesoap1]

Both gas and water must be bonded to the main earthing terminal (MET) of the installation using 10mm2 cable. These can either be run separately or via one unbroken cable linking both to the MET. See this article for more information: http://electrical.theiet.org/wiring-matters/22/bonding.cfm?type=pdf[/QUOTE]Hi, Thanks for the link. As both water/gas both come in approx 40 feet from boiler/ and consumer board, a continuous conductor from gas 600ml from meter, to water, which is all copper, apart from 3 feet of lead input,then to MET seems best choice. Does that sound ok? ps. Does C/H need bonding as well, Circs?

 

[mikely]

Hi, Thanks for the link. As both water/gas both come in approx 40 feet from boiler/ and consumer board, a continuous conductor from gas 600ml from meter, to water, which is all copper, apart from 3 feet of lead input,then to MET seems best choice. Does that sound ok? ps. Does C/H need bonding as well, Circs?

Yes, that sounds OK. There is no requirement to separately bond other parts of the C/H, such as the boiler. It is only services that could introduce a voltage (usually earth) into the installation that require bonding to the MET.

 

[joesoap1]

Hi, Thanks for the link. As both water/gas both come in approx 40 feet from boiler/ and consumer board, a continuous conductor from gas 600ml from meter, to water, which is all copper, apart from 3 feet of lead input,then to MET seems best choice. Does that sound ok? ps. Does C/H need bonding as well, Circs?

Yes, that sounds OK. There is no requirement to separately bond other parts of the C/H, such as the boiler. It is only services that could introduce a voltage (usually earth) into the installation that require bonding to the MET.

Thanks Mikely, and Tony.Much Appreciated. It,s only taken Homeserve 7 years to notice this, + other stuff, Boilers 17 years .old, all I want them to do is change C/h Diaphragm.Found 5 piddling faults,+ bonding. and 2 hours later left, no diaphragm change, another day.Already waited a week.Under contract.Good innit:.Think they are trying to tell me something:

 

[Agile]

As both water/gas both come in approx 40 feet from boiler/ and consumer board, a continuous conductor from gas 600ml from meter, to water, which is all copper, apart from 3 feet of lead input,then to MET seems best choice. Does that sound ok? ps.

Thats ambiguous!

The 10mm2 earth conductor can go from gas to water and then to meter.

But you cannot rely on the water pipe as the conductor! It has to be 10 mm2 all the way from gas to meter but it can earth other things on the way.

Tony

 

[joesoap1]

As both water/gas both come in approx 40 feet from boiler/ and consumer board, a continuous conductor from gas 600ml from meter, to water, which is all copper, apart from 3 feet of lead input,then to MET seems best choice. Does that sound ok? ps.

Thats ambiguous!

The 10mm2 earth conductor can go from gas to water and then to meter.

But you cannot rely on the water pipe as the conductor! It has to be 10 mm2 all the way from gas to meter but it can earth other things on the way.

Tony

Hi Tony, it is as you say. I would have thought lead, being not a bad conductor, coming direct onto copper throughout, would not have needed bonding.But, There,s nothing in the link regarding lead.being a earth pole.There is a old remnant of a bond clip on the lead, long abandoned.They must deem lead not so good a conductor. I,m no sparky.

 

[mikely]

The more conductive the water pipe is, the more important it is that it is bonded. The danger presented by gas and water supplies is that they can introduce an earth potential to the building that is different to the earth potential of the electrical supply (at the MET). The main bonding minimises the potential difference between exposed and extraneous conductive parts in the installation during an earth fault.

Tony, you are right that main bonding of an incoming service is not required where the service pipe and pipework within the installation are both of plastic. However, quoting from the BS7671:2008 On-site guide: ‘Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended unless it has been confirmed that any metal pipework within the building is not introducing earth potential.

 

[joesoap1]

The more conductive the water pipe is, the more important it is that it is bonded. The danger presented by gas and water supplies is that they can introduce an earth potential to the building that is different to the earth potential of the electrical supply (at the MET). The main bonding minimises the potential difference between exposed and extraneous conductive parts in the installation during an earth fault.

Tony, you are right that main bonding of an incoming service is not required where the service pipe and pipework within the installation are both of plastic. However, quoting from the BS7671:2008 On-site guide: ‘Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended unless it has been confirmed that any metal pipework within the building is not introducing earth potential.

Hi Mikely, can you clarify for me why the bonding has to be within 600mm of gas meter and water inlet, yet all of the pipes terminate in my garage at the boiler 5 feet from MET.on the same wall.? Whats the reason for running 2 X 40 feet of bonding cable paralell to pipework to MET, when it all can be bonded at 1 point in garage and run 5 feet to MET.Appreciate your advice, it,s very helpful. Cheers

 

[kirkgas]

The more conductive the water pipe is, the more important it is that it is bonded. The danger presented by gas and water supplies is that they can introduce an earth potential to the building that is different to the earth potential of the electrical supply (at the MET). The main bonding minimises the potential difference between exposed and extraneous conductive parts in the installation during an earth fault.

Tony, you are right that main bonding of an incoming service is not required where the service pipe and pipework within the installation are both of plastic. However, quoting from the BS7671:2008 On-site guide: ‘Where there is a plastic incoming service and a metal installation within the premises, main bonding is recommended unless it has been confirmed that any metal pipework within the building is not introducing earth potential.

Hi Mikely, can you clarify for me why the bonding has to be within 600mm of gas meter and water inlet, yet all of the pipes terminate in my garage at the boiler 5 feet from MET.on the same wall.? Whats the reason for running 2 X 40 feet of bonding cable paralell to pipework to MET, when it all can be bonded at 1 point in garage and run 5 feet to MET.Appreciate your advice, it,s very helpful. Cheers

the requirement for a gas pipe to be bonded within 600mm of the meter outlet comes from BS6891 (pipework install BS) which says the first 600mm of pipe needs to be rigid pipe before it changes to trac pipe etc, and the requirement to bond onto to rigid pipe, therefore it makes sense to ask for the bonding to be within 600mm so that it will always be on the rigid pipe, ask any spark where the bonding needs to be and he will tell you anywhere as long as the ze reading is correct, remember before we cut a pipe we should be using a temp continuity bond, so we should be protected wherever the spark has put the connection, (i think the sparks regs require the bond to be fitted within the equipotential zone where accessible) which with an outside meter and chipboard flooring could be 6m inside the prop beside the boiler