Heat damaged cables

[DESL]

I thought I would the stress the importance of replacing cables that have been damaged by overheating caused by bad connections or or arcing following drill damage.

Copper when heated to a high (non melting) temperature and allowed to cool naturally becomes brittle (the reverse of annealing steel)

This embrittlement will effect the mechanical strength of the copper.

 

[Pensdown]

Wrong way round...when you heat copper and leave it to cool it becomes soft

 

[bernardgreen]

And when there is arcing there is also the carbon and other combustion products that are forced along inside the outer sheath. For further than you may think at first glance.

 

[DESL]

Wrong way round...when you heat copper and leave it to cool it becomes soft

Are you sure - I seem to remember from my metalwork class at school that copper was annealed by heating and then quenching in water.

 

[bernardgreen]

Wrong way round...when you heat copper and leave it to cool it becomes soft

Are you sure - I seem to remember from my metalwork class at school that copper was annealed by heating and then quenching in water.

My memory is also that heating and sudden cooling would soften copper that had been hardened by being beaten into shape. But after the heating there was an oxide layer that had to be removed. Wire with a layer of oxide would not make a good connection other than where the rotating screw cut through the oxide down to clean copper.