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Strange C.P.C. attack and size reduction.

Evenin' all,

                         today I attended a shop store at a beach location. The store is on the prom just above high water level.


I decided to replace a double socket with rusty screws that the owner has suspicions about. The socket is wired in old 2.5/1.0mm2 T&E copper cable. There were three 2.5s connected at the socket, a ring pair and a spur. The live of the spur cable was blackened at the point where the sheath had been removed. The copper C.P.C. of the spur cable immediately snapped off when I moved it. It was discoloured and pitted along its length, but the weird thing is that its diameter reduced, pretty much consistently, the closer the C.P.C. was to the remaining sheath. When removed, the copper C.P.C. resembled a needle, tapering down in diameter towards the place where it broke off at the point of sheath removal. Was this due to historical tracking between live and C.P.C? Or was it electrochemical corrosion and weird physics? The damaged length was about 50mm long,


Z.


Parents
  • To become needle like as you describe material has to be dissolved more at one end than the other - that is indeed an electrolytic type thing, as the current density and therefore rate of solution rises in the regions that are nearer to whatever is acting as the other electrode. I'd be wondering if the backbox may have been full of salty water at some point in the past.
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  • To become needle like as you describe material has to be dissolved more at one end than the other - that is indeed an electrolytic type thing, as the current density and therefore rate of solution rises in the regions that are nearer to whatever is acting as the other electrode. I'd be wondering if the backbox may have been full of salty water at some point in the past.
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