Blackened live in switch

[sparkwright]

(I only said the second quote. )

 

[Harry Bloomfield]

So does apply to the already tinned copper cable frequently used nearly 60+ years ago?

No, there is no depth of solder on the directly tinned individual wires. I would not worry about that, just the method of solder tinning when terminating a flexible.

 

[JohnW2]

So does apply to the already tinned copper cable frequently used nearly 60+ years ago?

Intresting question.

However, I have to wonder whether we are not perhaps talking about 'chalk and cheese'. I'm not sure whether the 'tinning' of tinned copper cable is really comparable with manually-applied solder (in terms of 'squashability' etc.) and, even if it is such a coating was extremely thin, and very 'even'/'uniform', so very probably not so much of an issue when squashed by a terminal screw?

And is that why tinned copper cable isn't available now?

Perhaps, but it's presumably cheaper not to tin it, as well? Tinned copper wire is obviously still very widely available, and I use it all the time in electronic applications (where it is usually soldered, and very rarely has any interaction with terminal screws). Do not things like standard telephone wiring cable still have tinned copper conductors (even though they are sometimes used with 'screwed joints')?

I must say that I've never been sure about the intended purpose of the 'tinning', particularly for 'house wiring cables'.

Kind Regards, John

 

[Harry Bloomfield]

I must say that I've never been sure about the intended purpose of the 'tinning', particularly for 'house wiring cables'.

I doubt they did it for fun - I wonder if there might have some sort of chemical interaction between bare copper and the insulation?

VRI and the hard rubber (name?) cables were always tinned, some early PVC were too.

 

[JohnW2]

I doubt they did it for fun - I wonder if there might have some sort of chemical interaction between bare copper and the insulation?

Quite so. It presumably markedly increased the manufacturing complexity/cost, so there must have been a (perceived to be 'good') reason - but, as I said, I don't know what it was.

As you go on to say, the tinning preceded the advent of PVC cables, and I would be surprised if there were any 'chemical interaction' between copper and rubber.

As above, I just don't know - does anyone?

Kind Regards, John

 

[sparkwright]

Presumably the tinned part contributed to the actual cross sectional area?

 

[Harry Bloomfield]

Quite so. It presumably markedly increased the manufacturing complexity/cost, so there must have been a (perceived to be 'good') reason - but, as I said, I don't know what it was.

Fuse wire (remember those) were also tinned. I wonder how they did it, was it actually tin - maybe electro-plated?

 

[JohnW2]

Presumably the tinned part contributed to the actual cross sectional area?

Sure (very slightly - it was/is exceptionally thin), but so what? Are you suggesting it was done because 'tin' (or whatever it was/is) was cheaper than copper? If so, I doubt the price reduction due to the tiny proportion of the 'tin' involved would have even made up for the additional cost of manufacturing.

Kind Regards, John

 

[JohnW2]

... I wonder how they did it, was it actually tin - maybe electro-plated?

It seems that it was/is tin, that it was/is done either by dipping or electroplating, and that it's advantage (at higher cost) is corrosion resistance. I found this:

Oxidation Problems
If you’ve ever seen the Statue of Liberty, you’ve seen oxidized copper. In exceptionally humid climates, such as on the coastline, in swampy southern areas of the U.S., or in highly acidic soils, copper reacts to water, oxygen or sulfur in the environment and degrades into a semiconductor. In other words, the copper becomes far less efficient at moving electricity through itself. This problem is most often solved by a process called tinning.
Tinning Benefits
When you apply a thin coating of tin to bare copper wire, either by dipping the copper in molten metal or by using an electric current to bind the tin to the copper, you create what is known as tinned copper wire. Tinned copper wire is just as conductive as bare copper wire, but the thin layer of tin helps the wire resist corrosion. Tinned copper wire can last up to 10 times longer than its non-tinned counterpart, and because solder is composed primarily of tin, tinned wire is incredibly easy to solder. Tinned copper wire is particularly useful in industrial cranes, subways and marine projects where the tin coat makes the wire more resistant to water.
Cost Disadvantages
Despite the many benefits of tinned wire, it is not always the right wire for the job. Tinned copper wire is more expensive than its non-tinned counterpart and can cost as much as 30 percent more than basic, bare copper wire. In environments where acidic soil, high heat or high humidity are not concerns for a project, non-tinned copper wire works just as well.

Kind Regards, John

 

[RandomGrinch]

After completing many thousands of P. A. Test's, I would say the soldering together (not tinning of individual strands) of flexible strand mains leads to go into the screw terminals of a plug, is an extremely bad idea.
The soldered ends go brittle, leaving a break under the screw terminal. The cable will easily pull out leaving half still trapped in the terminal.

 

[JohnW2]

(I only said the second quote. )

You did. Some copying/pasting went a little awry there. My apologies - now corrected.

Kind Regards, John