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

 

[davesparks]

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..

Bonding for each installation is not optional, it either is, or is not, required.

Normally it is required, the fact that the pipework is bonded elsewhere makes it an extraneous part to the individual flats installation.

 

[Ian1981]

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

There no requirement for the continuity of a bonding conductor to be at or below 0.05 ohms.
The reading should reflect the length of the conductor serving the extraneous part, an engineering judgment should be made if the lengths are unknown, that the adequacy of the reading is acceptable.

 

[bigspark17]

Bonding for each installation is not optional, it either is, or is not, required.

Normally it is required, the fact that the pipework is bonded elsewhere makes it an extraneous part to the individual flats installation.

if there is only one MET by (DNO) and all appropriate main bonding is done to services that are coming into the building to the that MET why would they need supp bond withing the flat?

when i say optional, imo if the OP or others did bond in flat when it wasnt required i would be pendantic about that.

 

[Ian1981]

if there is only one MET by (DNO) and all appropriate main bonding is done to services that are coming into the building to the that MET why would they need supp bond withing the flat?

when i say optional, imo if the OP or others did bond in flat when it wasnt required i would be pendantic about that.

Usually you have a BNO for blocks of flats, each flat is a separate installation with individual metering and has their own MET. Bonding should be carried out in each individual flat if applicable.

 

[davesparks]

if there is only one MET by (DNO) and all appropriate main bonding is done to services that are coming into the building to the that MET why would they need supp bond withing the flat?

when i say optional, imo if the OP or others did bond in flat when it wasnt required i would be pendantic about that.

Because each individual flat has its own installation, and that installation should have its own main bonding to create its own equipotential zone.

 

[Ed Evans]

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

The answer is belt and braces. You can use one continuous piece of cable to bond the gas and water. Also it is bonded via the actual boiler when it is working. HOWEVER. if the boiler is changed when it is of the wall you lose the bonding provided by the boiler which is dangerous. When I have taught gas engineers I have instructed them all to use a temporary bond ie it looks a bit like a set of jump leads when you fit a new pump as again the bond is lost when you take the pump out. It has resulted in a plumber being killed when he touched both ends of the pipe at the same time.
also it does not take much time or materials to be sure. live long and prosper.

 

[davesparks]

The answer is belt and braces. You can use one continuous piece of cable to bond the gas and water.

The Cable does not have to be continuous/unbroken it can be a seperate piece of cable linking the two.

 

[Ed Evans]

The Cable does not have to be continuous/unbroken it can be a seperate piece of cable linking the two.

If you link the cable you will fail your AM2. it must be two separate runs or one continuous piece with NO joins.

 

[davesparks]

If you link the cable you will fail your AM2. it must be two separate runs or one continuous piece with NO joins.

Can you support this with a regulation?

As far as I know the AM2 doesn't overrule the wiring regulations, so the rules for the AM2 are largely irrelevant in the real world if they don't fall in line with the wiring regulations.

 

[pc1966]

If you link the cable you will fail your AM2. it must be two separate runs or one continuous piece with NO joins.

Most likely AM2 is following the examples given in the IET Guidance Note 8 (figure 5.5 on page 64 if anyone cares to look it up) but others have pointed out that is not an actual requirement in the regulations.

Best practice for sure, as we probably have all seen wires drop out of supposedly properly fixed screw connections (or some muppet disconnects it), which is a very good reason for teaching it that way.

But not absolutely necessary. There must be bonding of extraneous conductive parts, and it should be reliable and low resistance, but other approaches may be acceptable depending on the practicality of applying it.

 

[Ed Evans]

Can you support this with a regulation?

As far as I know the AM2 doesn't overrule the wiring regulations, so the rules for the AM2 are largely irrelevant in the real world if they don't fall in line with the wiring regulations.

The AM2 complies with the regs 100%

 

[Ian1981]

With all due respect , this is not the AM2 and there’s no requirement in bs7671 that states that a bonding conductor must be continuous.
It’s another myth imbedded into the industry much like the myth of the 0.05 maximum resistance figure which again is incorrect but it’s getting taught in colleges and is not inline with what bs7671 states.
For example if you came across this while conducting an EICR, you can’t code it anything as what regulation would it not comply with?

 

[Ed Evans]

With all due respect , this is not the AM2 and there’s no requirement in bs7671 that states that a bonding conductor must be continuous.
It’s another myth imbedded into the industry much like the myth of the 0.05 maximum resistance figure which again is incorrect but it’s getting taught in colleges and is not inline with what bs7671 states.
For example if you came across this while conducting an EICR, you can’t code it anything as what regulation would it not comply with?

If you get a copy of the Viper gas book it states that bonding must be looped

 

[Ian1981]

If you get a copy of the Viper gas book it states that bonding must be looped

But what does that have to do with bs7671?
Do they quote a regulation number?
Is this Viper book an official British standard on the requirements of electrical installations?
Or is it for gas engineers and has no actual factual electrical regulations to support its guidance?

 

[pc1966]

Best practice (IET Guidances Notes, AM2, Viper gas training, etc) often exceeds what the regulations demand.