Should wire be Twisted before Crimping?

[hexreader]

With reference to this post:

Here

I was taught that wire should not be twisted before crimping. Was I taught wrongly?

Also a ferrule seems like the wrong thing to use on a screw terminal to me.

(and the OP lives in US, but seems to have been given UK advice)

Sorry if this sounds like trolling, it isn't meant to be. I decided to start a new thread rather than cause confusion to OP on original thread.

Just curious, as the advice given seems at odds with things I have been doing for years.

What do others think please?

Many thanks, Robin

 

[KrisBlueNZ]

Maybe I was wrong. Based on my experience, crimping grips the wire a lot better when it's twisted. That' my rationale. Do you know the rationale for why they shouldn't be twisted?

I'd like to hear others' opinions too.

 

[hexreader]

Do you know the rationale for why they shouldn't be twisted?

No, but I always assumed that twisting allows the possibility of the finished item becoming partially or fully untwisted, which would reduce the wire diameter and weaken the crimp.

Untwisting would also lengthen the bare portion of wire, possibly leaving exposed wire in some circumstances?

But these are just assumptions made up by me. I have no definitive reference to support any of it.

I do trust the guy who told me not to twist, but sadly he did not explain why it was so important, and I did not think to ask.

I must admit that I sometimes give a very light twist just to get the strands to stay bundled so that all strands go into the ferrule/terminal.

Presumably the type of crimp tool used might have some bearing, but presumably not twisting would be acceptable in all circumstances.

And twisting somehow just "feels right", and is the first instinct if not trained to resist it.

Update: Googling has not given me any definite answer, and manufacturers' instructions seem to vary, but the impression I am left with is that a light twist (such as the twist the wire comes with) is a good thing, but over-twist is a bad thing. Luckily I am only a hobby builder now, so it is of trivial concern for me. When I used to crimp wires as part of my job, it would have been more important.

 

[Deleted member 36829]

Interesting question. When I was an apprentice one of my instructors was an ex-Navy EE (who had been one of their examiners/certifiers), and he insisted that:

1. untwisted wires should never be twisted before crimping, or at the very most only have the end twisted for insertion into the crimp;
   
2. twisted wires should only be lightly twisted (in the same direction as, and only enough to restore, their original twist) before crimping; and
3. when crimping multiple wires in a terminal, they should not be twisted together (and any tensile testing for certification should be performed only on the smallest wire)

The reason given was that crimps are designed to crimp down to a certain circular area (the area occupied by the bare wire; not the same as the cross-sectional area), and twisting the wire slightly increases that area - leading to over-crimping crushing & damaging the conductors & weakening the joint.

As I recall it was covered in the BPO/APO/Telecom training materials, but I can't point to anything definite to back it up. It does however support hexreader's info.

 

[KrisBlueNZ]

Thanks Xilef. That explanation sounds reasonable to me.

Edit: And welcome to Electronics Point

Please feel free to introduce yourself on the introductions thread in the introductions forum!

 

[davenn]

and the OP lives in US, but seems to have been given UK advice)

not so much UK, but a large part of the rest of the world.
I'm in Australia, (New Zealand and many other countries also use that colour code)
and it was just natural for me to select that pic from google

I never saw his location when I initially posted the cable colour info
apart from the fact that the flag shown can often be incorrect.
It was only this morning I confirmed his IP location in eastern USA

Ohhh and with ferrules ....
only keep strands twisted if they already were, else leave them straight before crimping is what I was taught

cheers
Dave

 

[Arouse1973]

My company has thousands of looms manufactured each year and we do not specify to twist the wires. For the reasons already pointed out, we were told the machine crimps to a certain depth and twisting could loosen the wire overtime.
Thanks
Adam

 

[hexreader]

Thanks Guys,

I feel a whole lot happier now

 

[Kiwi]

I don't twist wires in the uninsulated crimps like the one shown above.

I twist the wires in insulated automotive terminals, and give each one a good pull to make sure the wire is securely held.

 

[Tha fios agaibh]

I agree to not twist. Lugs are designed for a certain wire gage or diameter.
For smaller wire, I sometimes double the wire back(fold) and use a larger lug.

Read the packaging of your lugs, It will tell you the wire it was designed for.