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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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  • 0

    There has been no death. The wall will not be steam stripped of wall paper as it has recently been painted with new emulsion paint.



    I'm not sure that you can legislate your own BS7671 or H&S codes on the basis of an individual case. There has to be common ground for all electrical systems within each location (domestic is just one type). It is safe or it is not safe. A metal plate switch is either class 2 or not, if not then it is a class 1 accessory and must be earthed via a cpc. The regs do not allow us to use electrical separation in domestic environments as a sole method of basic protection. it also requires another layer of insulation to provide protection. An RCD will not provide the necessary shock protection even though by fortuitousness it may operate due to a minor current imbalance and current flow to an earthing point. 


    Legh
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  • 0

    There has been no death. The wall will not be steam stripped of wall paper as it has recently been painted with new emulsion paint.



    I'm not sure that you can legislate your own BS7671 or H&S codes on the basis of an individual case. There has to be common ground for all electrical systems within each location (domestic is just one type). It is safe or it is not safe. A metal plate switch is either class 2 or not, if not then it is a class 1 accessory and must be earthed via a cpc. The regs do not allow us to use electrical separation in domestic environments as a sole method of basic protection. it also requires another layer of insulation to provide protection. An RCD will not provide the necessary shock protection even though by fortuitousness it may operate due to a minor current imbalance and current flow to an earthing point. 


    Legh
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