Crimped ferrules (?) on ends of 13A cables

[The Natural Philosopher]

Which is why the neutral has arced, not the live, Obviously!

Dear oh dear.

Now try doing that with tinned copper wire.

That's *a* way of doing things

[pamela]

It's the live.

[Andy Burns]

Check if local college offers evening classes in sarcasm awareness.

[The Natural Philosopher]

Sarcasm pam.

His thesis is disproved by the effect that has happened.

Yet he blandly advances it as if it made sense.

[The Natural Philosopher]

[pamela]

What's the point of being sarcastic about the colour of the lead?

*puzzled*

[pamela]

It was a bit too deadpan for me!

Dunno.

Aren't there two points?

One: a loose live screw caused arcing. Two: tight earth and neutral screws caused solder creep.

[The Natural Philosopher]

There was a third point. If there is solder, tighten down hard. The solder creeps but the joint is tight

I.e teh failure was due to lack of tightening as shown by the ABSENCE of solder creep on the live wire.

Arcing is down to bad torque, not solder.

I've had plenty of plugs with bare wires that have arced as well.

[T i m]

It's a bloke thing. ;-)

(But it wasn't about the colour, it was about the issue).

There is a possibility the live could have been at a disadvantage because (over the neutral, although they would both be carrying the same current) because of any resistance of the fuse causing localised heating *and* lack of heat sink to the pin (and socket) for the screw terminal.

I will / do tin stranded leads where the situation suits and I have tinned them (and still will now and again) when I had fitted them in a

13 plug top and have *never* (in ~50 years) *ever* had any issues because of doing so.

Depending on the quality of the plug, the screws in the pin can either have a strand friendly ball end or a fairly flat / sharp face that can easily slice though a few strands (and where a ferrule / tinning can specifically help).

That's why many (often better quality) screw terminal blocks have a small steel tongue under the screw to prevent fine strands being cut / missed out.

Cheers, T i m

[Dave Plowman (News)]

I've never ever had a screw terminal slice through a few strands. More likely is they were partially cut when stripping the insulation. All to easy, if not using the correct tool.

More to allow a wide range of cable sizes to be used. Not needed on a mains plug.

[T i m]

You are either very lucky, only use quality components or don't use very fine / flexy cables. ;-)

Quite. ;-)

'As well' I'd say (unless you can find something that defines the role formally etc). I say that because I have seen (and use) some electronics where the aforementioned 'protected' screw terminal wasn't really big enough for the sort of gauge wire you might typically use with it (like the chassis mounted SMPSUs we have used). So, had the terminal been 'big' and you wanted to use a smaller wire (... than would be sufficiently rated to match the output of the PSU for example), your explanation would have been more likely (in that case etc). They also come into their own when attaching more than one of a similar diameter cable (side by side for example, rather than twisting the two together and putting them in as one or trying to put them in side by side without twisting and risking losing some strands).

Hmm, I'd say I might like such a thing on a mains plug as I always feel more confident when using connectors with them than without. With you just apply a broad clamping force whereas without, you *do* risk cutting through the conductors (as I have done more than once). That said, mains flex doesn't normally come with as many strands as some 'high flex' cables so they wouldn't generally be as much of an issue.

It's a similar idea with the Mk (and possibly others) round terminals and washer protected 'nuts' (that didn't rotate on the wire as you did up the 'nut') and so that cable was 'only' clamped, no risk of a conductor being sheared.

Cheers, T i m

[dennis]

The neutral is too long, the earth is too short. I always try and make it so the earth is the last thing that can pull out if the cord grip fails to do its job.

[dennis]

For the benefit of Brian..

Its a 13A plug with one of the wires burnt.

The neutral is the blue wire on the left that shows no sign of burning or arcing. The live is the brown one going to the fuse on the right that is burnt and shows signs of arcing.

[dennis]

Its always a joke when TNP gets something wrong, you should have noticed that from previous posts.

[dennis]

Solder creep is what causes the screw to loosen over time which is why you get the arcing. You can see the indentations in the wire/solder where the screws were tightened at one time. The solder then moves out under the pressure from the screw which reduces the pressure allowing the screw to loosen under vibration and/or heat cycles. Its why you use crimps if you can unless you want stuff to fail sooner.

[The Natural Philosopher]

Oh dear dennis, The whole thing has passed over your head even higher than pamelas.

[The Natural Philosopher]

No it isn't.

Only in the ones that HAVENT arced

The only crimps you use dennis are in your pubic hair.

[dennis]

Of course it is.

Everyone can look at the photo and see you are lying! There are screw indents in all the wires. Maybe you should have gone to specsavers?

[The Natural Philosopher]

And the smallest indent is in the wire that arced, because it wasnt tightened down Maybe you should have gone to specsavers?

[Harry Bloomfield]

dennis@home a écrit :

I used to sometimes tin the ends, but having seen the results of solder creep numerous times, I stopped doing it. No amount of tightening the terminal screw can apply enough pressure to avoid the problem. The solder creeps, the terminal becomes loose, the lead oxidises and it over heats sometimes melting the solder.