Crimped ferrules (?) on ends of 13A cables

[Harry Bloomfield]

The Natural Philosopher a écrit :

I suggest the difference in the depth of indent is due to the solder melting and flowing out of the live copper.

[pamela]

Oi! :-)

[The Natural Philosopher]

make up whatever stories you like. You obviously cant solder. All the copper should be as much in contact with itself as without solder. thats only supposed to fill the gaps.

[dennis]

Careful the TNP has lost it and will throw insults at you for suggesting what actually happens.

[Harry Bloomfield]

The Natural Philosopher a écrit :

I very obviously can solder...

Tinning the flex will hold the stands of the flex in a certain position as the screw is tightened. As the solder migrates gradually under the screw's pressure the terminal can then become loose. Just tinning the flex can be difficult to achieve, without their being some bulk of solder involved.

As said, I did once beleive that tinning flex was best practise, but not now having seen lots of evidence to the contrary. Solder with a compression connection, is an absolute no, no.

[Capitol]

Each end of the wire would have been numbered. normal practice is only one colour of wire for a given current/voltage rating.

[Capitol]

Agreed.

[Capitol]

Criming is good on stranded wires subject to vibration. However, you are always at the mercy of the crimp tool and wire behaviour. I have had many more crimp failures than screw terminal failures over the years I have been wiring equipments. Crimping is generally very poor on reliability with solid wires if there are temperature changes. Hence the popularity of wire wrap.

[dennis]

8<

Wire wrap forms a cold weld which is gas tight, if its done with correct tool and wire.

[Mike Tomlinson]

En el artículo , The Natural Philosopher escribió:

The same current flows through the neutral wire, so either could have arced. You're getting more and more like D i m.

The whole point is that tinning wire ends before putting a plug on is deprecated, as it leads to solder creep and bad/arcing contacts.

You also conveniently ignored the point that tinning converts the wire end into a single soft block of metal which is easy to pinch off if the screw is overtightened.

Crimped ends, being harder metal, don't creep under the screw pressure.

Quite.

Doubling the wore over maximises the surface contact area between the wire and the plug body, reducing the likelihood of a high resistance connection developing.

I took the photos of the plug in question. That alone was evidence enough for me that tinning wire ends isn't a good idea and I haven't done it since.

[The Natural Philosopher]

What? I really believe your brain has turned to MUSH.

what happened to all those copper wires?

magically become part of some new alloy?

MO wonder people want to stay in the EU.

No one has a brain left after 40 years of socialist state education.

[T i m]

On this we agree. The problem with people like Tomlinson is they are never wrong (in their own heads).

Quite. He's talking complete and utter BS.

If you tin some stranded wire you are just binding the (copper) together with another conductor (tin / lead) and as long as you don't go OTT with the solder (where you end up with surplus solder on / over the strands) then doing so can have little mechanical impact over the original copper strands, other than keeping them together better.

If you push (particularly fine) stranded wire into a conventional screw type terminal (chock block / 13A plug pin) and without twisting the strands there is a very good chance several things could happen:

1) Some stands may not make it into the connector. 2) Some strands won't get clamped by the screw (and will go up the sides of the screw). 3) Because the stands are fine they can be easily cut by the rotating end of the screw as it clamps.

The second option is to twist the conductors and assuming the twist stays together as you tighten the screw, could be better than not twisting.

However, a better solution might be to twist and tin, (and even twist, double over and tin if the wire is small enough) and that way you don't suffer any of the issues noted above.

I have been doing just that for nearly 50 years and never had any issues. Maybe I know how to properly tin a cable and how to properly tighten a screw and Tomlinson doesn't. ;-(

Cheers, T i m

[Dave Plowman (News)]

Odd that pretty well every terminal you find on a car, from Trabant to Bentley, is crimped.

Of course I'd not expect crapitol to know as with everything else it is possible to crimp something badly.

[Capitol]

How much manufacturing experience do you have? None?

[The Natural Philosopher]

Hellofa lot here.

Aerospace and commercial electrical and electronics.

I will repeat what I said elsewhere. Given the cost constraints on making a good soldered,supported, sleeved joint in a *car*, crimping or IDC is really the only viable way to make up mass produced looms at sensible costs. That doesn't mean it's the best.

However cars don't usually die at the roadside from bad joints, so its obviously *good enough*.

wire wrap and IDC is however deemed to be better *electrically* but that doesn't take into account mechanical strength.

Soldering is almost never used for wring because its a difficult way to connect wires to terminals or plugs and sockets on a production line.

[Andrew Gabriel]

It's never permitted to do this because the solder creeps over time under pressure and contact pressure is lost, causing the connection to then overheat.

[MM]

As I understand it (e.g. the use of the word "deprecated"), tinning

*used* to be the recommendation?

MM

[MM]

Also, this last recommendation in that article...

"Thirdly if using pre-tinned wire ends, the easy fix for the problem (if you don't want to cut and strip) is to very gently torque up the screw on the main power and heater wires after some hundred hours of use. After a few times all the solder that can yield has flowed out of the way and you have a good copper to brass mechanical contact. You do not want to over tighten the screws and you also don't want to loosen them when doing this maintenance, just a careful torquing it up to take up the slack without repositioning it in a new orientation."

...seems totally fine.

And what bog-standard 3-pin 13A plugs (e.g. Wilko, Tesco, Asda) have tongues in the screwed posts? I don't recall ever seeing them.

MM

[MM]

I tin the wires exactly for that purpose, i.e. to keep the strands together while the end is inserted into the screwed post. It also makes for a very neat job, in my opinion. Note that I said *TIN*. That doesn't mean putting a large blob of solder on the end! Less is more, as they say.

Yep, twist then tin is what I do.

I served 7 years as an apprentice motor fitter so I know a bit about over-tightening screws or nuts.

You get a feel for how tight is tight after 60 years.

MM

[Andy Burns]

But does the average person, after fitting a 13A plug, go back several times each after a few hundred hours and re-tighten it?