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Topic Title: Crimping solid core cables
Topic Summary: yes or no?
Created On: 13 July 2011 08:30 PM
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 13 July 2011 08:30 PM
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dickllewellyn

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Where did the rumours begin on this?

So many so called electricians when asked would suggest that solid core cables cannot or should not be crimped. Where did this idea come form, and is there any basis behind it?

I personally have no problem with crimping solid conductors, and believe that done properly provides a much better connection than a screw terminal, yet still some people rubbish the idea.

Or maybe I'm the one who's wrong?

-------------------------
Regards
Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 13 July 2011 08:41 PM
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daveparry1

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I think the same as you Dick, although I do make sure I don't waggle the cables about after crimping as this can cause them to loosen. BTW, stranded cable is much better to crimp, i've often had to crimp 7/029 when extending an old ring for instance and it does give a much more positive feel,

Dave.
 13 July 2011 08:42 PM
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Grumpy

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I await with bated breath cos I know what I do!
 13 July 2011 08:47 PM
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stateit

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I'd ssuggest if a crimp on a solid-core cable loosens after 'waggling' you don't have a very good, or correctly set, crimping tool.

-------------------------
S George
http://www.sg-electrical.com
 13 July 2011 08:51 PM
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WalkersWiring

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After reading your last post & looking at your avatar, it appears that you like a good waggle, Stateit!!

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Regards -

Jerry

The bitterness of poor quality lasts long after the sweetness of a cheap price...
 13 July 2011 08:52 PM
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spinlondon

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You can with a lot of effort, remove a crimp from a solid core, more easilly than from a stranded core.
 13 July 2011 08:55 PM
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1652

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It take the same effort... a sharp pair of snips.
 13 July 2011 09:02 PM
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daveparry1

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No matter how good the quality of the tool Stateit, just simple mechanical engineering experience would tell you that a piece of solid, fairly stiff wire inside a fairly thin-walled tube (the crimp tube) would be easily loosened by moving the two around too much in relation to each other,

Dave.
 13 July 2011 09:02 PM
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jointersmate

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HV cables with solid conductors still get crimped so can't see a problem with it. Although i have forgotten what a crimper looks like since i started working for the board as it all seems to be shear off lugs.
 13 July 2011 09:22 PM
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davezawadi

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well Dick, try it out!
On small cables say 2.5 or less then the usual coloured crimps do not do well. On larger cables with the proper crimper then they are fine. I did some tests a year or two ago and reported them her, no one took much interest.
Crimp a red crimp with a ratchet tool onto a 1.0 conductor. Try to pull it off with the crimp held in the vice. Result?
Try a stranded 1.0 cable, result?
Same for 1.5 then 2.5. results?

Then try a large say 25mm piece of HV cable with the correct crimp and tooling. Result?
The a 600 mm piece of aluminium and the correct crimp and tooling (you may need a hydraulic setup to test this...)

Your own view? Please report back!

David

-------------------------
David
CEng etc, don't ask, its a result not a question!
 13 July 2011 09:32 PM
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ant1uk

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Originally posted by: davezawadi
On small cables say 2.5 or less then the usual coloured crimps do not do well. On larger cables with the proper crimper then they are fine. I did some tests a year or two ago and reported them her, no one took much interest.

Crimp a red crimp with a ratchet tool onto a 1.0 conductor.


Tell me your joking you don't use those diy crimps do you? now you got me worried
 13 July 2011 09:36 PM
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dickllewellyn

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I wonder what sort of torque equivalent you get with a crimped solid conductor... Perhaps with manufacturers jumping on the band wagon of stating torque settings for screw terminals, crimp lugs may even be a better connection!

Whilst on the subject of terminations, just reading PE magazine, and I see Ideal have launched a new version of the "screw-it"!

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Richard (Dick)

"Insert words of wisdom and/or witty pun here"
 13 July 2011 10:20 PM
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stateit

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So when do you guys use crimps on the smaller 1 - 2.5mm solid core cables in a situation where the cable is likely to be subject to movement then?

Never I'd guess.

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S George
http://www.sg-electrical.com
 13 July 2011 10:25 PM
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daveparry1

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Just when placing the joined section into an enclosure or similar situations Stateit, eg if inside a c/unit I get the cables as near to their final position as possible before crimping them. All i'm saying is that once crimped, don't move them around too much,

Dave.
 14 July 2011 07:57 AM
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Pacific

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Served my time working to MOD standards, crimping solid cores was strictly forbidden, I have always stuck to that ruling, rightly or wrongly
 14 July 2011 08:56 AM
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ant1uk

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You won't pul off a crimp with my crimper! Once its on you have to cut the cable to get it off. You must be using the wrong crimper or have it adjusted wrong. I did spend a few quid on it though.
 14 July 2011 09:25 AM
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davezawadi

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Well well, why do none of you try out my experiments? I don't put them here for fun you know, a quick experience is worth a thousand words.....

Now the, the coloured crimps, strange how they are in so many installations. Coloured crimps with the correct ratchet preset load crimp tools are fine on stranded conductors, they are no use at all on 1 or 1.5 solid conductors and very poor on 2.5 solid cables, and it is true that the MOD equipment practice does not allow them (or any of the more fancy versions by AMP etc on these kinds of wires). Crimped with cutters (see it often) or a simple plier tool they are completely useless, moved or not. The way to test all varieties of crimped connections is the pull test, the joint is pulled until something fails. If it the wire is pulled from the crimp it is no good, if the wire itself breaks first it is satisfactory. Crimp a tag onto a solid wire, put the tag in the vice and pull until it breaks. With solid wires they usually pull out of coloured tags. Quite different with stranded wires.

Now the bigger crimps. Large solid cables are often crimped with indentor tools, which press an area of the tag metal into the conductor forming a mechanical interleave and a contact with very high pressure. They go from about 10mm2 up and are very reliable. You will not pull any of these by hand, the proper test machine is necessary. Hex crimps are also satisfactory on solid wires but the crimp force is very large indeed, and the proper tooling is essential. They do not cover solid T&E sizes.

In my view, coloured crimps should not be used on solid conductors! Code C2 unless over heated in which case C1. (526.2)

-------------------------
David
CEng etc, don't ask, its a result not a question!
 14 July 2011 11:02 AM
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broadgage

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From a practical point of view I have a great distrust of crimped connections except in very low current control or data circuits.

With a qaulity tool, good materials and a skilled operator, it SHOULD be possible to make reliable crimped connections with a long term current carrying capacity no less than the conductors joined.

In practice though crimped connections are a frequent source of failures. My work is largely maintenance and repair, and a very large proportion of faults that I rectify are burnt out crimped connections.
This applies both to crimps done on site by installers, and to crimped connections within equipment done on a production line.
Solid conductors seem worse than stranded.

I have just investigated ANOTHER non functioning twin 13 amp socket in an office. It had been moved and the conductors extended by crimps, neutral burnt out and the phase had clearly got very hot.
The remaining cable was too short and damaged to re-use, so spent an interesting hour "fishing" new cable through a wall.

I must have repaired a dozen portable A/C units, every single one had burnt out crimp terminals on the internal wiring.
Failed small appliances are seldom worth repair, but if one can be bothered, failed crimp terminals are a common fault.

Edited: 14 July 2011 at 12:33 PM by broadgage
 14 July 2011 06:58 PM
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daveparry1

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David, I did try your experiment several years ago and on both 1.5 and 2.5 single core the wire broke.
Ant, I have never had any worries about cables pulling out but I stand by what said earlier about them having a tendency to become loose in the crimp if twisted or moved around too much close to the joint, not enough for them to pull out but enough to cause a possible h/r connection,

Dave.
 14 July 2011 07:46 PM
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GJH

Posts: 496
Joined: 24 January 2008

I never have a problem, i always give them a tug when ive crimped them and they are fine.

Nothing says you cant crimp on solid cores?
IET » Wiring and the regulations » Crimping solid core cables

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