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

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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.


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    MHRestorations:

    The form of corrosion you're describing is usually due to DC in my experience, so electrochemical action is a strong contender.


    The pitting might suggest previous water ingress (salt water during a storm perhaps?)

    The 'rusty' part is telling... rust in contact with the copper, in the presence of salt... would do it




    The mounting pattress was secured by very rusty 70s steel screws, the slots of which had corroded away due to rust.


    We had a storm in 2013 that may have flooded the store area under the shop and allowed sea water to enter the socket pattress. The store is unheated as it only stores beach balls and deck chairs etc. It is damp.


    Z.




     

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  • 0

    MHRestorations:

    The form of corrosion you're describing is usually due to DC in my experience, so electrochemical action is a strong contender.


    The pitting might suggest previous water ingress (salt water during a storm perhaps?)

    The 'rusty' part is telling... rust in contact with the copper, in the presence of salt... would do it




    The mounting pattress was secured by very rusty 70s steel screws, the slots of which had corroded away due to rust.


    We had a storm in 2013 that may have flooded the store area under the shop and allowed sea water to enter the socket pattress. The store is unheated as it only stores beach balls and deck chairs etc. It is damp.


    Z.




     

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