Clarification on gas bonding please

[MickSmith5824]

Hi. Could someone please clarify bonding requirements for me please. I know requirements are to have a seperate 10mm earth bond conductor for water and gas or that these can be in one cable if looped between each other. I have been working in a couple of properties lately that are in residential blocks. The both have combi boilers installed. I have noticed that they don't have any seperate bonding to gas. Just one 10mm that goes to water. Is this in breach of current regs? Thing i dont quite understand is as far as I am aware all pipe work of combi boiler is interconnected so if the bond the water pipes is in place then in effect the water and gas pipes of boiler are also aren't they? If this isn't adequate and a dedicated gas bond needs to be provide is the any solution to situations where meter is situated outside apartments and can't find where enters property or where access in a near on impossibility. Any advice/clarification be appreciated

 

[Pete999]

Hi. Could someone please clarify bonding requirements for me please. I know requirements are to have a seperate 10mm earth bond conductor for water and gas or that these can be in one cable if looped between each other. I have been working in a couple of properties lately that are in residential blocks. The both have combi boilers installed. I have noticed that they don't have any seperate bonding to gas. Just one 10mm that goes to water. Is this in breach of current regs? Thing i dont quite understand is as far as I am aware all pipe work of combi boiler is interconnected so if the bond the water pipes is in place then in effect the water and gas pipes of boiler are also aren't they? If this isn't adequate and a dedicated gas bond needs to be provide is the any solution to situations where meter is situated outside apartments and can't find where enters property or where access in a near on impossibility. Any advice/clarification be appreciated

Do you have a Gas metre or entry to your property?

 

[MickSmith5824]

Do you have a Gas metre or entry to your property?

Both of the properties have been working in lately have gas meters in communal areas of apartments

 

[Pete999]

Both of the properties have been working in lately have gas meters in communal areas of apartments

)hen bond to the communal area.? discuss, or within 60mm from where it (the gas pipe) enters your apartment, discuss

 

[pc1966]

The reasons for bonding the gas pipe as it enters come down the the possibility of a poor electrical connection between pipework, as plumbers have no need to make it electrically sound and might even replace bits with plastic for repairs/extensions/etc.

The guide notes shows a continuous wire but others have pointed out the actual regs don't specify that. Somewhere I have seen it said that a "permanent" join such as solder or crimp is also acceptable, but again no reference to the regs.

Often the say/show it at the meter, but again from the flat's point of view the extraneous conductive part is pipe coming in, if the meter is miles away then you would only bond to the incoming pipe.
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What I did in my flat (for better or worse!) where the lead water pipe and gas meter are close together under the kitchen sink was to run a length of 16mm from the MET to the water pipe and then crimped it using a 35mm M6 ring terminal (to connect to the water pipe clamp) along with another length of 16mm that was terminated with a 16mm M6 ring terminal (for the pipe clamp to the gas).

NOTE: My use of 16mm was simply due to having a reel of it handy!

 

[davesparks]

What I did in my flat (for better or worse!) where the lead water pipe and gas meter are close together under the kitchen sink was to run a length of 16mm from the MET to the water pipe and then crimped it using a 35mm M6 ring terminal (to connect to the water pipe clamp) along with another length of 16mm that was terminated with a 16mm M6 ring terminal (for the pipe clamp to the gas).

That is incorrect, you should have fitted a 16mm lug to each conductor.
Putting 2 conductors into a lug which is designed for a single conductor of a different size is wrong, it is not approved by the manufacturer, may not achieve the correct finished crimp profile and pressure.

 

[MickSmith5824]

The reasons for bonding the gas pipe as it enters come down the the possibility of a poor electrical connection between pipework, as plumbers have no need to make it electrically sound and might even replace bits with plastic for repairs/extensions/etc.

The guide notes shows a continuous wire but others have pointed out the actual regs don't specify that. Somewhere I have seen it said that a "permanent" join such as solder or crimp is also acceptable, but again no reference to the regs.

Often the say/show it at the meter, but again from the flat's point of view the extraneous conductive part is pipe coming in, if the meter is miles away then you would only bond to the incoming pipe.
[automerge]1588090731[/automerge]
What I did in my flat (for better or worse!) where the lead water pipe and gas meter are close together under the kitchen sink was to run a length of 16mm from the MET to the water pipe and then crimped it using a 35mm M6 ring terminal (to connect to the water pipe clamp) along with another length of 16mm that was terminated with a 16mm M6 ring terminal (for the pipe clamp to the gas).

NOTE: My use of 16mm was simply due to having a reel of it handy!

Cheers PC I think in these scenarios I have no option but to find closest point can get access to pipework in property. Just to clarify there's no scenarios in 18th regs that a 6mm is adequate. Whether it's tns or tncs has to be 10mm for both gas and water?

 

[davesparks]

Cheers PC I think in these scenarios I have no option but to find closest point can get access to pipework in property. Just to clarify there's no scenarios in 18th regs that a 6mm is adequate. Whether it's tns or tncs has to be 10mm for both gas and water?

It is required to be half the size of the earthing conductor and no less than 6mm except when PME conditions apply.

Bonding in a block of flats should be carried out at the point of entry to the building (landlords installation) and at the point of entry to each flat.

 

[MickSmith5824]

It is required to be half the size of the earthing conductor and no less than 6mm except when PME conditions apply.

Bonding in a block of flats should be carried out at the point of entry to the building (landlords installation) and at the point of entry to each flat.

Thanks Dave. So for TNCS supplies has to be minimum 10mm

 

[pc1966]

That is incorrect, you should have fitted a 16mm lug to each conductor.
Putting 2 conductors into a lug which is designed for a single conductor of a different size is wrong, it is not approved by the manufacturer, may not achieve the correct finished crimp profile and pressure.

True it is not ideal, but the pipe clamp would not realistically take two 16mm crimp lugs. I did a reasonable pull-test on the crimp to make sure it was holding, and also it is not required to carry its rated current here.

 

[bigspark17]

Do the flats have there own DNO supplies or are they feed from a switch room with one large DNO supply in it?

 

[davesparks]

Thanks Dave. So for TNCS supplies has to be minimum 10mm

The same rules apply for TNCS.
If PME conditions apply then it is usually a minimum size of 10mm.
TNCS is not necessarily a PME supply.
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True it is not ideal, but the pipe clamp would not realistically take two 16mm crimp lugs. I did a reasonable pull-test on the crimp to make sure it was holding, and also it is not required to carry its rated current here.

It is required to be an electrically and mechanically sound connection, which it may not be as it has been used incorrectly.
There's more to it than just a pull test, if you haven't achieved the correct crimping then the connection may well corrode and become high resistance or fail when current flows through it.

There's a lot more to a good crimped connection than just squashing bits of metal together.

 

[MickSmith5824]

Do the flats have there own DNO supplies or are they feed from a switch room with one large DNO supply in it?

They both are fed from ryfield boards that are on the communal landings

 

[bigspark17]

They both are fed from ryfield boards that are on the communal landings

the bonding should have been done from this location assuming one gas supply is for the building, bonding from within the flats would be optional in most of these situation if appropriate tests confirmed this..

 

[MickSmith5824]

the bonding should have been done from this location assuming one gas supply is for the building, bonding from within the flats would be optional in most of these situation if appropriate tests confirmed this..

Thanks bigspark your the only one who's ever clarified that. Is there any section in regs mentions this or links you know of that talks about scenarion more in depth. Would the testing just be testing between MET and any gas pipework can access and having reading below 0.05 and also the same between water and gas