Do you use crimps on solid conductors??

[djrichie_t]

DONT!!!!

They work loose over time especially if a fair amount of current has gone through them due to expansion/contraction (heating/cooling) and can overheat/catch fire! Using them on stranded conductors is fine, even better if the cable is more flexible (like tri-rated switchgear wire) but if its solid copper, use choc blocks and remember to double the conductor over .

You may find that DNO installation inspectors will fail an installation and refuse to connect a meter should they suspect an installation uses crimps like this.

If you have to put lugs on to solid conductors, use solder and heatshrink. Might be more time consuming but certainly improves the quality of work done.

Note: This advice applies to the small red/yellow/blue crimps used on smaller conductors, the larger ones are fine as the crimp is much more secure.

 

[toasty]

really?

I'm not sure a screw terminal is any better really, surely they can work loose too.

I'm a big fan of soldering, but would have thought that crimps were better than chocblocks.

..Umm...discuss!

 

[djrichie_t]

Screws have alot more solid weight behind them than crimps, and if the conductor is doubled over in a screw terminal then it wont come loose if tightened properly.

Crimps can only go so tight, however they hardly pinch on any (solid) conductor, certainly much less than a screw will.

With a screw, its held in a thread but a crimp is only its own thing, and not held in anything.

With less proper surface area to make contact with, a crimp will slowly heat/cool and work loose.

 

[bernardgreen]

With a properly made crimp joint in some electronic assembly there is a degree of cold weld between the crimp barrel and the conductor.

Does that happen in electrical crimps ? If so they would be very reliable

 

[djrichie_t]

It doesnt happen with small electrical crimps. Be nice if it did

 

[RF Lighting]

What a lot of sh1te

"A DNO man will not connect a meter if he suspects a crimp on a solid conductor."


I'm just off down the hospital to have my sides stitched back together.


Do you have any actual facts to validate your claims?


Isn't it strange how Tyco / Ampliversal don't specify stranded wire only for use with their insulated crimps?

 

[djrichie_t]

What a lot of sh1te

"A DNO man will not connect a meter if he suspects a crimp on a solid conductor."


I'm just off down the hospital to have my sides stitched back together.


Do you have any actual facts to validate your claims?


Isn't it strange how Tyco / Ampliversal don't specify stranded wire only for use with their insulated crimps?

It has happened, its in the guidelines. Plus when i was working for the electricity board as an engineer i sometimes got asked to help other departments, and that included installation inspections, upon which it was advised to look out for crimp connectors and check their integrity. We could also over-rule normal sparky's tests and fail the installation should there be anything untoward the use of these type of connectors as they are very crude.

I personally have had to do 2 incident reports after fires broke out in properties, which were caused by the use of crimp connectors on solid conductors.

Problem is, the regs do have contradictions within themselves which always have to be ironed out... but if an installation causes a fire then the reason has to be found.

Again, its work integrity. Crimps are a quick-fix which are not good in the slightest, and in my professional opinion, using crimps like those i mentioned, on an installation is not a proper way of doing things.

 

[RF Lighting]

A properly fitted crimp is a far superior connection compared with its screwed counterpart.

You only have to try and pull either one apart to see which makes the most sound connection.


I will be the first to say that badly fitted crimps will fail very quickly.

meets the requirements of military standards MIL-T-7928 and BS4G178. The terminals are constructed from high grade copper. The crimp barrel having inner serrations to ensure maximum contact with the stripped wire

Crimps are good enough for the military

 

[djrichie_t]

A crimp is a far superior connection compared with its screwed counterpart.

You only have to try and pull either one apart to see which makes the most sound connection.

meets the requirements of military standards MIL-T-7928 and BS4G178. The terminals are constructed from high grade copper. The crimp barrel having inner serrations to ensure maximum contact with the stripped wire

... Which is why they work loose? - crimps are good on stranded conductors, pull them apart on solid conductors anyday. Its the minute spark-gap created by the higher voltage that is used (240v) that causes the probs.

 

[RF Lighting]

You will snap the conductor before the crimped joint fails.

 

[LeeJC]

Multicore or single core doesn't matter the aerospace industry/defence industry all use crimps no matter what the signal level is. That includes helicopters which suffer from slightly more vibration than your average house.

Crimps can fail, but they mostly fail due to poor installation, a correctly fitted crimp will out last (vibration and thermal cycling) any screwed terminal.

 

[djrichie_t]

Its not the vibrations but the flow of mains voltage through them, i've seen it happen which is why i made the original post.

I know why it happens with solid conductors.... I have done military work myself, wiring up challenger 2's and crimps are no prob as the conductors used in these are stranded. This means that when you go to crimp the strands mould better into the shape of the squashed crimp.

Solid conductors (1.0mm, 1.5mm and 2.5mm) do not squash very easy which means that the actual crimp is hardly pinching on anything.

 

[RF Lighting]

Thats why you use a proper ratchet crimper, to ensure the solid conductor makes a full and proper contact with the crimp.

 

[Lectrician]

Its not the vibrations but the flow of mains voltage through them, i've seen it happen which is why i made the original post.

I know why it happens with solid conductors.... I have done military work myself, wiring up challenger 2's and crimps are no prob as the conductors used in these are stranded. This means that when you go to crimp the strands mould better into the shape of the squashed crimp.

Solid conductors (1.0mm, 1.5mm and 2.5mm) do not squash very easy which means that the actual crimp is hardly pinching on anything.

What havn't you done?

Seems you have worked in every area of lecky..............but not stuck long in any of those areas?

 

[LeeJC]

Can't speak for challenger tanks, however merlin,nimrod, Airbus Range, Seaking, Lynx and a few others which i only know the company name for all use single core crimped conductors for 400v 200hz.