Main Bonding with a crimped lug fixing!

[LmarshallSparks]

Hey All,

At college, I was taught that main bonding - such as bonding to a gas pipe - must be carried out using a continuous copper conductor running directly from the Main Earthing Terminal (MET) to the pipework, with no extensions or alterations permitted. If the bonding cable is damaged or contains any connections, it must be replaced entirely. However, is it acceptable to use a crimped lug to improve the connection to the earthing clamp? My college instructors would argue that this introduces an unnecessary connection and, therefore, isn’t allowed.

 

[ELECNEWT]

Hey All,

At college, I was taught that main bonding - such as bonding to a gas pipe - must be carried out using a continuous copper conductor running directly from the Main Earthing Terminal (MET) to the pipework, with no extensions or alterations permitted. If the bonding cable is damaged or contains any connections, it must be replaced entirely. However, is it acceptable to use a crimped lug to improve the connection to the earthing clamp? My college instructors would argue that this introduces an unnecessary connection and, therefore, isn’t allowed.

I agree with your college instructors.

 

[brianmoooore]

I'd be happy with any strong joint that cannot be dismantled, and a properly crimped lug meets this requirement.

 

[Jock from the north]

Hey All,

At college, I was taught that main bonding - such as bonding to a gas pipe - must be carried out using a continuous copper conductor running directly from the Main Earthing Terminal (MET) to the pipework, with no extensions or alterations permitted. If the bonding cable is damaged or contains any connections, it must be replaced entirely. However, is it acceptable to use a crimped lug to improve the connection to the earthing clamp? My college instructors would argue that this introduces an unnecessary connection and, therefore, isn’t allowed.

Is there a preferred method for connecting a single 10mm to clamp .I've seen sparkys use the forked 3 and 4 method which I think is bad practice as its uneven,I've even worked with guys who have cut off a core for this very reason .I've seen it just stuck in one side of clamp where the wind could blow it off .I personally loop my conductor round screw ,can't see that been any different then a continuous loop .

 

[James]

I think a correctly sized and crimped joint is going to be both physically and electrically superior to simply clamping the conductor in the bonding clamp.

edit:
Also, You come across many installations where a MET is situated on the meter back board and a single cable goes from there to the consumer unit. from the consumer unit, bonding cables go out to the water and gas.
I personally think this is fine but is not in line with the above post.

 

[brianmoooore]

I have always stripped off about 20mm of insulation, about 50mm from the end of the wire. Twist the cores straight in the exposed gap, make a hole between 4 and 3 wires and screw though there.

 

[Jock from the north]

I have always stripped off about 20mm of insulation, about 50mm from the end of the wire. Twist the cores straight in the exposed gap, make a hole between 4 and 3 wires and screw though there.

That would do it .as long as the wire is supported (not on the pipe) I think either method leaves a solid connection where wire can't be moved

 

[Pretty Mouth]

Hey All,

At college, I was taught that main bonding - such as bonding to a gas pipe - must be carried out using a continuous copper conductor running directly from the Main Earthing Terminal (MET) to the pipework, with no extensions or alterations permitted. If the bonding cable is damaged or contains any connections, it must be replaced entirely. However, is it acceptable to use a crimped lug to improve the connection to the earthing clamp? My college instructors would argue that this introduces an unnecessary connection and, therefore, isn’t allowed.

I would ask your college instructors to point out the regulation(s) that state or imply these things. 544 is the section on protective bonding conductors. I see nothing in there, or in chapter 54 generally, that suggests that bonding conductors must be a single continuous cable from MET to extraneous part, or that connections are not allowed. Or even that it has to be copper.

 

[Pretty Mouth]

Is there a preferred method for connecting a single 10mm to clamp .I've seen sparkys use the forked 3 and 4 method which I think is bad practice as its uneven,I've even worked with guys who have cut off a core for this very reason .I've seen it just stuck in one side of clamp where the wind could blow it off .I personally loop my conductor round screw ,can't see that been any different then a continuous loop .

Sometimes I use the 3 - 4 split method, particularly with larger conductors. The clamps I use have a captive washer that seems to deal with the imbalance. It seems to be a solid connection anyway.

Looping round the screw works well with smaller conductors, but I feel it doesn't make a good connection with larger conductors.

 

[Avo Mk8]

I would ask your college instructors to point out the regulation(s) that state or imply these things. 544 is the section on protective bonding conductors. I see nothing in there, or in chapter 54 generally, that suggests that bonding conductors must be a single continuous cable from MET to extraneous part, or that connections are not allowed. Or even that it has to be copper.

Yes. I've seen the following quote on the IET forum, which is where the concept might have come from:
"the uncut bit isn't a BS 7671 requirement, but is recommended by BS 7430'
BS7430 being the Code of Practice for the Protective Earthing of Electrical Installations
2011 + A1 2015 and still current, but not exactly up-to-date
And no, I haven't read it !

 

[Pretty Mouth]

Yes. I've seen the following quote on the IET forum, which is where the concept might have come from:
"the uncut bit isn't a BS 7671 requirement, but is recommended by BS 7430'
BS7430 being the Code of Practice for the Protective Earthing of Electrical Installations
2011 + A1 2015 and still current, but not exactly up-to-date
And no, I haven't read it !

Aha. I have a copy of BS7430, but it's the 1998 edition, so long out of date. FWIW, this is what it has to say:

Where both main gas pipes and main water pipes
enter a location, a common bonding conductor may
be used, but in such cases that conductor should be
continuous or should be permanently jointed (by
soldering or crimping) in order to preserve
continuity. Such a bonding conductor may also be
used in association with other
extraneous-conductive-parts.

EDIT: a quick online search and I now also have a copy of BS7430-2011 unamended. Exactly the same wording as the 1998 ed.

EDIT 2: another online search, and I have now have the 2015 amendment. Again, the same wording as the 1998 ed.

 

[brianmoooore]

Don't remember where or when it came from, but my understanding of the relevant regs was the same as the OP's instructor, so I assume the continuous cable was the requirement at some point, even if not now.
I've always been quite happy to disregard it if joins have been permanent and mechanically strong.

 

[Jock from the north]

Aha. I have a copy of BS7430, but it's the 1998 edition, so long out of date. FWIW, this is what it has to say:

Where both main gas pipes and main water pipes
enter a location, a common bonding conductor may
be used, but in such cases that conductor should be
continuous or should be permanently jointed (by
soldering or crimping) in order to preserve
continuity. Such a bonding conductor may also be
used in association with other
extraneous-conductive-parts.

Don't remember where or when it came from, but my understanding of the relevant regs was the same as the OP's instructor, so I assume the continuous cable was the requirement at some point, even if not now.
I've always been quite happy to disregard it if joins have been permanent and mechanically strong.

Seem to remember that supplementry equipotential bonding at bathroom rads could be soldered under floor for unsightly earth clamps with no access required for inspection if certain regs were met to stop plumbers cutting them off when fitting fancy radiators .I believe it was in the earthing snags and solutions 17th eddition ,not that I've ever attempted it but it had to be on the return pipe and obviously would be a single 4mm as appose to a loop but we'll out of date now

 

[brianmoooore]

No, I'm referring to bonding to metallic services entering the property, such as gas, oil and water.
Long before the 'bond everything in a bathroom' nonsense. The radiator clamps actually came with a yellow crimp lug.

 

[Jock from the north]

No, I'm referring to bonding to metallic services entering the property, such as gas, oil and water.
Long before the 'bond everything in a bathroom' nonsense. The radiator clamps actually came with a yellow crimp lug.

I realise that I'm just waffling.the rad clamps only really fitted a normal radiator ,iv got loads in my screw box.a fancy rounded tall radiator could really on be clamped on metal pipe which when the customers paying 7 grand for a bathroom they and the bathroom fitter would tend to cut them off or so the niceic thought so a soldered joint was a solution to the issue .I've actually found the book and it's quite interesting,especially the do's and don'ts concerning the use of earth clamps

 

[Rockingit]

Ahhh….. this old fable. It’s a complete misunderstanding of the intent. It does not mean that you need one uninterrupted length of seamless conductor - as others have said, that’s as illogical as it is impractical. What is MEANT is that where you have bonding to points A, B & C (such as for example Hot, Cold and Gas on a boiler) if you remove point A for maintenance then points B&C are still connected in circuit. So that means either doing a loop thru connection on a clamp - or - guess what??……. Use a crimped lug. 2 x 10mm in a flared 16/6 with a good quality crimper and that’s never coming apart.

 

[LmarshallSparks]

Thanks all so much! It sounds like the general consensus is, a good crimped connection will be absolutely fine, however wrapping around the connector or making a fork and clamping down is also fine so no real harm either way? As long as all connection are mechanically strong!