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.

In article ,
John Rumm wrote:
Well, I wired this house some 40 odd years ago. Not has a problem with any
terminal working loose. Perhaps because I tightened them correctly in the
first place? I have worked on other installations where this wasn't so,
though. And wondered if it was an electrician making work for the future?

Much depends on the circuit IME... Lighting circuits never run anywhere
close to the full rated capacity of the cable, and there is very little
thermal expansion and contraction, and no heating effect other than at
the terminals other than those on the lamp fittings themselves.

Circuits that cycle up to close to maximum load seem more susceptible to
problems. Other factors like how well cables are supported and even the
length of individual runs of cable can play a part.

True. Probably why I don't have any JBs etc in high current circuits.

But do you have problems with the screw connections in your CU? Riser?
Meter?

--
*You're never too old to learn something stupid.
Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
FMurtz wrote:
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.

Yes. And difficult to tell since covered in plastic. I only now buy them
from TLC.

--
*I get enough exercise just pushing my luck.

Dave Plowman London SW
To e-mail, change noise into sound.

On 20/01/2020 10:44, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
Well, I wired this house some 40 odd years ago. Not has a problem with any
terminal working loose. Perhaps because I tightened them correctly in the
first place? I have worked on other installations where this wasn't so,
though. And wondered if it was an electrician making work for the future?

Much depends on the circuit IME... Lighting circuits never run anywhere
close to the full rated capacity of the cable, and there is very little
thermal expansion and contraction, and no heating effect other than at
the terminals other than those on the lamp fittings themselves.

Circuits that cycle up to close to maximum load seem more susceptible to
problems. Other factors like how well cables are supported and even the
length of individual runs of cable can play a part.

True. Probably why I don't have any JBs etc in high current circuits.

But do you have problems with the screw connections in your CU? Riser?
Meter?

I have met a number of Wylex style rewireable fuse CUs where the
terminals were no longer "tight" - even if there were no obvious signs
of overheating as such.


--
Cheers,

John.

/================================================== ===============\
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| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 20/01/2020 10:48, Dave Plowman (News) wrote:
In article ,
FMurtz wrote:
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.

Yes. And difficult to tell since covered in plastic. I only now buy them
from TLC.


IIRC I got mine from CPC, and they have been fine.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
John Rumm wrote:
But do you have problems with the screw connections in your CU? Riser?
Meter?

I have met a number of Wylex style rewireable fuse CUs where the
terminals were no longer "tight" - even if there were no obvious signs
of overheating as such.

But were they ones you installed yourself so know they were tight to start
with?

As I said, I've come across plenty faults due to terminals not being
tightened properly.

--
*When I'm not in my right mind, my left mind gets pretty crowded *

Dave Plowman London SW
To e-mail, change noise into sound.

On 20/01/2020 15:14, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
But do you have problems with the screw connections in your CU? Riser?
Meter?

I have met a number of Wylex style rewireable fuse CUs where the
terminals were no longer "tight" - even if there were no obvious signs
of overheating as such.

But were they ones you installed yourself so know they were tight to start
with?

Not usually... but then again they have often been loose enough it would
be hard to believe that they were originally left like that (and also
where the wire ends show deformation from the original clamping pressure)

I have installed CUs and then a year later checked tightness on all the
termination screws. Even when properly tightened originally, applying
similar torque again will sometimes get a bit of movement.

As I said, I've come across plenty faults due to terminals not being
tightened properly.

Yup also a typical failure mode, but some relaxation and creep of
terminations also seems common.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 20/01/2020 18:23:30, John Rumm wrote:
On 20/01/2020 15:14, Dave Plowman (News) wrote:
In article ,
Â*Â*Â* John Rumm wrote:
But do you have problems with the screw connections in your CU? Riser?
Meter?

I have met a number of Wylex style rewireable fuse CUs where the
terminals were no longer "tight" - even if there were no obvious signs
of overheating as such.

But were they ones you installed yourself so know they were tight to
start
with?

Not usually... but then again they have often been loose enough it would
be hard to believe that they were originally left like that (and also
where the wire ends show deformation from the original clamping pressure)

I have installed CUs and then a year later checked tightness on all the
termination screws. Even when properly tightened originally, applying
similar torque again will sometimes get a bit of movement.

As I said, I've come across plenty faults due to terminals not being
tightened properly.

Yup also a typical failure mode, but some relaxation and creep of
terminations also seems common.

I have long considered the loosening of terminals is down to thermal
expansion and cycling. We are led to believe that copper suffers very
little creep.

Using:

https://www.engineeringtoolbox.com/l...ents-d_95.html

The difference between expansion coefficients for copper and brass is
around 2 x 10-6, so for a worse case 50C temperature rise it should give
rise to an expansion difference of 0.1%

Whether that is enough to overcome any pretensioning or if movement is
the killer I'm not sure.

In article , Fredxx
scribeth thus
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.

Is there an alternative convenient and affordable method recommended
where access is not required.


Your doing something wrong, used thousands over the years not one has
been a problem.

However you do need decent ratchet crimpers, the pliers type ones are
useless!..

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article ,
tony sayer wrote:
In article , Fredxx
scribeth thus
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.

Is there an alternative convenient and affordable method recommended
where access is not required.


Your doing something wrong, used thousands over the years not one has
been a problem.

However you do need decent ratchet crimpers, the pliers type ones are
useless!..

I've seen lots and lots of problems with pre-insulated terminals DIY
fitted on cars.

--
*Marathon runners with bad footwear suffer the agony of defeat*

Dave Plowman London SW
To e-mail, change noise into sound.

On 2020-01-19, John Rumm wrote:

On 19/01/2020 11:57, Dave Plowman (News) wrote:
In article ,
Adam Funk wrote:
On 2020-01-17, Brian Gaff (Sofa 2) wrote:

If access is not required surely nobody could know what you did, ie a
junction box.

Until years later, when the terminals work loose & the lights start
flickering (or worse).

Well, I wired this house some 40 odd years ago. Not has a problem with any
terminal working loose. Perhaps because I tightened them correctly in the
first place? I have worked on other installations where this wasn't so,
though. And wondered if it was an electrician making work for the future?

Much depends on the circuit IME... Lighting circuits never run anywhere
close to the full rated capacity of the cable, and there is very little
thermal expansion and contraction, and no heating effect other than at
the terminals other than those on the lamp fittings themselves.

Well, the one I had a problem with was for the kitchen lights. One
morning they wouldn't light & I noticed that walking on the bathroom
floor (directly above) made them work. We moved in a little over 20
years ago, so it must have taken at least that long for it to work
loose.



Circuits that cycle up to close to maximum load seem more susceptible to
problems. Other factors like how well cables are supported and even the
length of individual runs of cable can play a part.

(Obviously all that makes sense.)

On 22/01/2020 11:11, Dave Plowman (News) wrote:
In article ,
tony sayer wrote:
In article , Fredxx
scribeth thus
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.

Is there an alternative convenient and affordable method recommended
where access is not required.


Your doing something wrong, used thousands over the years not one has
been a problem.

However you do need decent ratchet crimpers, the pliers type ones are
useless!..

I've seen lots and lots of problems with pre-insulated terminals DIY
fitted on cars.


Are you using a decent crimp tool ie not one of the simple ones which
are just two bits of flat metal with notchs?

I wouldn't say I've never had problems with a crimp joint made with a
proper crimp tool but certainly they are few and far between. The
number plate lamps on our motorhome were intermittent and I noticed them
on a trip so returning to the dealer was really practical. I nipped up
one of the crimps (lated replaced- I don't carry a crimp tool so a nip
had to do for the time being) which cured it but that is the only one I
recall in years.

Conversely, Scotch-loks are the invention of the devil and I only use
then for quick lash ups etc to try things.

In article ,
Brian Reay wrote:
I've seen lots and lots of problems with pre-insulated terminals DIY
fitted on cars.


Are you using a decent crimp tool ie not one of the simple ones which
are just two bits of flat metal with notchs?

I'd not dream of using pre-insulated crimps on a car. I use the correct
ones and have the correct crimp tool.

I wouldn't say I've never had problems with a crimp joint made with a
proper crimp tool but certainly they are few and far between. The
number plate lamps on our motorhome were intermittent and I noticed them
on a trip so returning to the dealer was really practical. I nipped up
one of the crimps (lated replaced- I don't carry a crimp tool so a nip
had to do for the time being) which cured it but that is the only one I
recall in years.

It's well worth carefully cutting off the insulation from a pre-insulated
type and seeing the actual crimp. A decent crimp uses a heart shaped die
which makes the crimp grip the conductor all round. The pre-insulated type
merely flattens it. Which might be OK on solid core mains cable, but not
ideal with multi-strand. Of course it will work OK when new, but some
years down the line?

Conversely, Scotch-loks are the invention of the devil and I only use
then for quick lash ups etc to try things.

--
*Go the extra mile. It makes your boss look like an incompetent slacker *

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Dave Plowman (News)
scribeth thus
In article ,
tony sayer wrote:
In article , Fredxx
scribeth thus
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.

Is there an alternative convenient and affordable method recommended
where access is not required.


Your doing something wrong, used thousands over the years not one has
been a problem.

However you do need decent ratchet crimpers, the pliers type ones are
useless!..

I've seen lots and lots of problems with pre-insulated terminals DIY
fitted on cars.



Yes as most use those useless cheap crimp pliers!

With the ratchet ones they just do not move ever again!!


--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 2020-01-18, Fredxx wrote:

On 17/01/2020 17:06:52, Adam Funk wrote:
On 2020-01-17, Andrew wrote:

On 17/01/2020 16:15, 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.

Is there an alternative convenient and affordable method recommended
where access is not required.

Correctly made crimp joints with a decent ratchet crimper should
not pull apart. Something else is wrong with your technique or
equiopment.

I have a ratchet crimper from TLC Direct (recommended here by someone
knowledgeable, IIRC). I did some practice work (on offcuts of cable)
& found that I got better results after adjusting the crimper one
notch (then I started using it "for real").

Is this their DV DHCR15 tool?

I can't find the e-mail with the order details, but this definitely
looks like the one I have, which I know I got from TLC:

https://www.tlc-direct.co.uk/Products/DVDHCR15.html

The picture shows an adjustment wheel held in place by a small screw.
When I got the crimper, it was on the lowest setting, & I got good
results (i.e., really can't pull the wires apart) by adjusting it up
one position. (I suppose it adjusts further as the jaws wear out.)

In article , Adam Funk
scribeth thus
On 2020-01-18, Fredxx wrote:

On 17/01/2020 17:06:52, Adam Funk wrote:
On 2020-01-17, Andrew wrote:

On 17/01/2020 16:15, 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.

Is there an alternative convenient and affordable method recommended
where access is not required.

Correctly made crimp joints with a decent ratchet crimper should
not pull apart. Something else is wrong with your technique or
equiopment.

I have a ratchet crimper from TLC Direct (recommended here by someone
knowledgeable, IIRC). I did some practice work (on offcuts of cable)
& found that I got better results after adjusting the crimper one
notch (then I started using it "for real").

Is this their DV DHCR15 tool?

I can't find the e-mail with the order details, but this definitely
looks like the one I have, which I know I got from TLC:

https://www.tlc-direct.co.uk/Products/DVDHCR15.html

The picture shows an adjustment wheel held in place by a small screw.
When I got the crimper, it was on the lowest setting, & I got good
results (i.e., really can't pull the wires apart) by adjusting it up
one position. (I suppose it adjusts further as the jaws wear out.)

There're the good ones

--
Tony Sayer


Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

On 2020-01-24, tony sayer wrote:

In article , Adam Funk
scribeth thus
On 2020-01-18, Fredxx wrote:

On 17/01/2020 17:06:52, Adam Funk wrote:
On 2020-01-17, Andrew wrote:

On 17/01/2020 16:15, 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.

Is there an alternative convenient and affordable method recommended
where access is not required.

Correctly made crimp joints with a decent ratchet crimper should
not pull apart. Something else is wrong with your technique or
equiopment.

I have a ratchet crimper from TLC Direct (recommended here by someone
knowledgeable, IIRC). I did some practice work (on offcuts of cable)
& found that I got better results after adjusting the crimper one
notch (then I started using it "for real").

Is this their DV DHCR15 tool?

I can't find the e-mail with the order details, but this definitely
looks like the one I have, which I know I got from TLC:

https://www.tlc-direct.co.uk/Products/DVDHCR15.html

The picture shows an adjustment wheel held in place by a small screw.
When I got the crimper, it was on the lowest setting, & I got good
results (i.e., really can't pull the wires apart) by adjusting it up
one position. (I suppose it adjusts further as the jaws wear out.)

There're the good ones

Good, thanks!