Overtightening Meter Terminals

[westward10]

So here is a connection I made to a bonding clamp today. I have wrapped it and the clamp can be tightened no more, even went back to it and is still rock solid. You will notice the conductor has retained its shape with no shift to the strands.

 

[Flipsy]

Had a scare today tightening, screw all the way right with a modular driver then went over them again then last time with a flat head. Heard creek/crack on one of the screws. Undid it, looked in the barrel, looked at the screw, replaced the screw. Tightened all up again and bit the wire no visible cracks and still tightened. So I dunno what went wrong there. Checked everything made sure nothing was cracked or broken and the new screw didn’t just turn in the barrel either.
This just wouldn’t happen with a torque driver. I tugged the wire as well. I also for peace of mind have taken apart a spare electric meter and basically tried destroying the cables, the terminals with a drill to tighen and done everything in my power to cause as much damage as I can above what I would normally do and everything seems fine on the test meter. So I think I’m clearly worrying over nothing. But I like to test things to destruction to see how fragile the equipment I’m working with is.
I think the weird crack noise might have been either the screw turning a bit and making a squeak or the flat head slipping slightly. But could not find anything damaged.

 

[Simon47]

It's not uncommon to get some sort of "crack" when nipping up an already tight terminal (or nut and bolt, or ...). Once tightened and static, there is significant stiction to be overcome before it will move again - so you apply pressure, nothing happens till you overcome the stiction, then there's a release as things move before settling down at the dynamic friction level which is much lower for most materials.
Few materials, brake pad linings are one of them, have stiction that is lower than dynamic friction - hence the effect of "nothing happens, then something 'gives', and things move with less effort than needed to get it moving". This is also why it's generally a good idea to loosen something before checking it is tight to a specific tightness level - if it's already tight, it may be stuck in place (especially with something like a steel wheelnut against a steel wheel and which has been in place for a long time) and the torque wrench setting isn't sufficient to overcome the stiction and you get a false sense of tightness.

 

[Flipsy]

It's not uncommon to get some sort of "crack" when nipping up an already tight terminal (or nut and bolt, or ...). Once tightened and static, there is significant stiction to be overcome before it will move again - so you apply pressure, nothing happens till you overcome the stiction, then there's a release as things move before settling down at the dynamic friction level which is much lower for most materials.
Few materials, brake pad linings are one of them, have stiction that is lower than dynamic friction - hence the effect of "nothing happens, then something 'gives', and things move with less effort than needed to get it moving". This is also why it's generally a good idea to loosen something before checking it is tight to a specific tightness level - if it's already tight, it may be stuck in place (especially with something like a steel wheelnut against a steel wheel and which has been in place for a long time) and the torque wrench setting isn't sufficient to overcome the stiction and you get a false sense of tightness.

Thanks really good advice. Makes me sleep easier at night lol.