John Rumm wrote:
On 18/01/2020 11:08, Fredxx wrote:
On 18/01/2020 03:21:39, FMurtz wrote:
Fredxx wrote:
In the good old days I would have used junction boxes but now these
have to be 'accessible' I ought to use an alternative.

I have tried crimps in the past and been thoroughly disillusioned
with them. I have found them unreliable and easily pulled apart,
even with ratchet crimping pliers.

You are not doing it right.

1) Strip wires
2) Place wires in crimp of the correct size
3) Place crimper around crimp in the correct 'notch'

I am sure you are doing it right, but just for the avoidance of doubt,
the crimp needs to be positioned in the tool set back from the end such
that the tool only compresses the part of it that contains the metal
crimp terminal, and not the "spare" bit of insulated sleeve at the end.

http://wiki.diyfaq.org.uk/index.php/...pInTheJaws.jpg

4) Squeeze handle of crimper as many times as required
5) Pull test pass/fail
6) If fail tighten crimpers and use new crimp if appropriate
7) Repeat and use new crimp if appropriate until success

The technique sounds fine.

Perhaps I'm tightening the crimpers too far? Either way I can
generally pull out the wires, or at least one.

The pull out resistance should be "firm" or better, but not necessarily
impossible. A well made crimp will typically be harder to pull a wire
from than from a screw terminal - but you can do it with enough force
since copper is soft enough to deform with enough load. If they are
pulling out easily, then it might suggest the crimps or the tool are not
well enough matched or of adequate quality.

As to crimping too far - it seems unlikely unless flattening the
terminal so much it actually splits along one side. The crimp should
deform the wire a little - although short of cutting open a crimp that
is harder to asses. (I might try that later)



Also there is a variation in the quality of the actual crimp fitting, I
have had a batch from an electronic shop as opposed to an electrical
wholesaler that were soft or otherwise faulty.