Tinned Copper Conductors

[dullSpark]

Maybe some kind person can tell me why we did use tinned copper cables for domestic final circuits and no longer do so? I'm afraid my trawling of the internet has not come up with an answer so far.

 

[Fred_Fanackapan]

The only disadvantage of using tinned cables I know of is when using screw terminals. The tin coating can creep with time and so loosen the connection.

Thinking about it the same will happen with crimp connectors.

 

[kai]

Tinned conductors were used in the past, when imperial sized 3/029 and 7/029 was the norm, the tinned coating was probably to enable soldering to take place easily, as many joints were soldered and filled with tar in those imperial cable days.

 

[empip]

'To Tin or Not to Tin...'
http://www.allbusiness.com/energy-utilities/utilities-industry-electric-power/6234616-1.html

Marine use?

 

[dullSpark]

Ahh, brilliant, the mist is starting to clear.
On the subject I found some disconnected lead sheathed cable, on stripping back it looked in perfect condition, shiny conductors, rubber soft and the cotton in great condition.
I almost felt like re-using it.

 

[empip]

Tinned conductors were used in the past, when imperial sized 3/029 and 7/029 was the norm, the tinned coating was probably to enable soldering to take place easily, as many joints were soldered and filled with tar in those imperial cable days.

I wonder how often 3 x 0.036" ( 1.97mm² ) was misidentified as 3 x 0.029" ( 1.28 mm² ) ?
The former was rated 19 amp the latter 15 amp - clipped direct, unenclosed.
http://electrical-contractor.net/PC/IEE1966_T3.jpg
Some others...
7 x 0.029" ~ 2.98 mm² with 3 x 0.036" ~ 1.97 mm² cpc
7 x 0.036" ~ 4.59 mm² with 7 x 0.029" ~ 2.98 mm² cpc

A 0-1" micrometer can be useful...

 

[JohnD]

OOI, "new" tinned copper is easy to solder, but "old" tinned copper isn't. I understand the tin molecules creep over time and it becomes fully alloyed, hence won't re-alloy to the new solder (solder works by forming an alloy, not as a "glue")