Earth Bonding Gas & Water Pipes

Yes - looping a bonding conductor uncut on a BS 951 clamp is acceptable (the uncut bit isn't even a BS 7671 requirement, but is recommended by BS 7430). Although if the water is plastic out of the ground (and the metal pipework doesn't later go underground or into to another installation) it probably doesn't need main bonding anyway.

   - Andy.

Or if not looped around the crew, for a bare section to be opened up 3 strands and 4 strands and the screw fitted between?


I don't think so Clive. Reading BS951 (albeit the 1999 copy). 5.2 suggests that the termination shall be capable of being possible to loop in and out.


I've always read this as the conductor under the screw shall be of equal size under both sides of the screw head. Taking an extreme example, 10 mm2 one side and 4 mm2 the other side would grip the 10 mm2 but leave the 4 mm2 loose. Do you agree Clive?


I would consider this to apply also to 4 and 3 strands as you describe.


I would also think that putting the 10 mm2 under one side, ie without looping round the screw to be also a no no.


If I were to find the conductor as you describe with 3 strands one side and 4 strands the other side, I would observe and record that the installer to obtain confirmation from the manufacturer that this method of using his product in this manner is compliant with BS951. Not one installer has forwarded this confirmation so has elected to simply re-terminate by looping round the screw with 7 strands each side. 


Whilst this may appear to some practitioners as harsh, the effort in removing a piece of insulation and forming the conductor into a loop round the screwdriver and then putting the screw through it, might take a few seconds longer than jabbing the screwdriver through the strands to separate into 3 and 4.


Regards


BOD

I'm going to disagree with BOD!


Whichever way you do it, there is a tendency for the strands to be flattened between the washer and the clamp.


If you poke the screw through, one side may be a little flatter than the other, but that's why there is a washer rather than just a screw head - it is able to slope a little whilst making contact.


If you loop round a full 360°, you have 7 strands under most of the washer, but 14 where they cross over, so that must be worse.


By my reckoning, you only need to go round 180°, which forms an omega shape.


I think quicker and easier to form a loop than poking a screwdriver through the middle.


The reason for not cutting the cable is supposed to be that if the first termination is removed, the second one remains intact.

Chris

Whichever way you do it, there is a tendency for the strands to be flattened between the washer and the clamp.

Some brands don't have a separate washer, just the rigid screw head with a "built in" washer as one integral rigid item

If you poke the screw through, one side may be a little flatter than the other, but that's why there is a washer rather than just a screw head - it is able to slope a little whilst making contact.

As above

If you loop round a full 360°, you have 7 strands under most of the washer, but 14 where they cross over, so that must be worse.

Perhaps I should have said only a 180 degree loop in case someone took it to mean 360 degrees!

By my reckoning, you only need to go round 180°, which forms an omega shape.

Fully agree as was my inference

I think quicker and easier to form a loop than poking a screwdriver through the middle.

And less risky to the paws!

The reason for not cutting the cable is supposed to be that if the first termination is removed, the second one remains intact.

As per the various guides, including the old RECs books for contractors on PME. and the late Geoffrey Stokes' book 12.3.1 along with GN8


Plus of course the alleged unwillingness for manufacturers of the BS951 clamps to confirm the 3 + 4 etc combinations. Perhaps you'll have more luck Chris!


Regards


BOD

Far too rough attempting to wind 10mm2 conductors round BS951 bonding clamp connection lugg.

Try this:


Legh

perspicacious:

...


I would also think that putting the 10 mm2 under one side, ie without looping round the screw to be also a no no.


...

The new Tenby clamps are designed to do exactly this. There is a groove for through wiring, see Tenby Rapid Clamp Ultra (legrand.co.uk)

I can't see the "safety.." label on the fitting, unless its on the other side.


A screw head terminal without a separate captive washer does not seem to comply with BS951:2009 which i just found on the web, but don't think i can post a link to here.

Hmm. Interesting to see that it appears that the pretty 15 mm copper tube image is terminated with 6 mm2..................


So it appears to be only suitable for sizes A to C, never 10 mm2 onto a 15 mm copper tube.......


The devil is in the detail................... As usual...............


Regards


BOD

full 10mm around (approx 180 degrees) always.

Even do that on last one (or the only one) unless using a eyelet crimp, kwick turn on end - prevents puill out on loose screw.

Whatever convoluted replies are given, bonding a water pipe that is not an extraneous-conductive-part is not required and should not be done.