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Shock Likelihood at Switch.

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Mornin' All,


I have just inspected and tested a renovated  old flat's wiring. The original lighting wiring in places has no circuit protective conductor. The owner has installed metal plate light switches to two positions with wooden back boxes. At these two positions there is no circuit protective conductor. The flat has a new R.C.B.O. consumer unit and all other wiring is good.


I have recommended that the switches have a C.P.C. installed (difficult and disruptive) or be changed to all insulated types.


Just what is the shock risk at these two switch positions? What is the likelihood of the metal plates becoming live due to a fault? Has anyone every seen a metal plate switch break down so that the plates becomes live?


Thanks,


Z.

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    perspicacious:

    ...... But it could happen............ There was some time ago a comparison between the likelihood of getting 4, 5, 6 numbers correlated with loss of limbs, sight etc. Not good reading.




    Nobody who plays the Lottery with a serious hope of winning would ever fly in an aeroplane, or even (much worse) have a surgical operation. Of course in the last case, the hope of a cure (of something life-threatening rather than just inconvenient) balances the risk.


    Has anybody ever correlated the risk of shock with the cost of reducing the risk? I suspect not.


    I suspect that most people wouldn't want to get involved in electrickery because they would perceive the risk as being high. However, if their lights come on, their heaters heat, and their motors go round and round, they don't give a moment's consideration as to whether the installation is actually safe.


    ETA, at Christmas I was thanked for installing the new wall lights in the sitting room. They do indeed look good and shed plenty of light where it is needed, but my motivation for doing the work was to keep my daughter and family safe. The rewire continues and for the most part, except for the new wooden switches, you wouldn't know that anything had been done.

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  • 0

    perspicacious:

    ...... But it could happen............ There was some time ago a comparison between the likelihood of getting 4, 5, 6 numbers correlated with loss of limbs, sight etc. Not good reading.




    Nobody who plays the Lottery with a serious hope of winning would ever fly in an aeroplane, or even (much worse) have a surgical operation. Of course in the last case, the hope of a cure (of something life-threatening rather than just inconvenient) balances the risk.


    Has anybody ever correlated the risk of shock with the cost of reducing the risk? I suspect not.


    I suspect that most people wouldn't want to get involved in electrickery because they would perceive the risk as being high. However, if their lights come on, their heaters heat, and their motors go round and round, they don't give a moment's consideration as to whether the installation is actually safe.


    ETA, at Christmas I was thanked for installing the new wall lights in the sitting room. They do indeed look good and shed plenty of light where it is needed, but my motivation for doing the work was to keep my daughter and family safe. The rewire continues and for the most part, except for the new wooden switches, you wouldn't know that anything had been done.

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